This is something I’ve tried to tell people for years. Easily one of the best bang for buck modifications you can make to your car. Every time I modify a car, one of my first purchases is an upgraded rear anti-roll bar.
It's good for smooth roads... It makes the ride much rougher on bad roads though. The double edged sword of stiffness. It does take away some comfort. Depending on where you live, If comfort is the priority, don't do it. Otherwise it definitely helps in cornering handling and stability
I thought that was common sense, it’s pretty well known in 4x4 when you raise the car more than 3 inches to not just lose all steering or rolling over in the first sharp turn
Funny story, this trick is how I used to beat the pants off of people in the old video game Gran Tourismo. It was billed as a "driving simulator" and bragged about a realistic physics engine. That's what got me interested in it, and I wasn't disappointed. In that old game, sway bars and lightening were the under appreciated modifications that could turn a boring compact into a consistent winner. My general tactic for cheapest results was to fit the "racing" level bars, both front and rear. These offered the greatest adjustment range, and I'd start with the front on full soft, and the rear midway. I'd consistently beat far more powerful cars with little effort. It would rotate very fast in low speed turns, fairly neutral in faster turns, and allowed full power on corner exits a lot earlier than my overpowered, understeering, rear drive competitors. Works in real life too.
The ND Mazda MX-5 might be one of the exceptions among modern performance cars, very soft suspension setup and pretty good handling balance from the factory.
It also benefits from 50-50 weight distribution and very low overall weight :) I would guess these factors allow it to have a soft suspension and maintain good dynamics
This is the exact problem I'm fighting, and while I found the answer myself through hours of research I'm glad to have the confidence of this video backing it.
It's even better than that! It's true that the sway bar increases outer wheel load on the axle it's mounted at, reducing that axle's cornering grip. Additionally, it also increases wheel load on the diagonally opposed wheel on the other axle, as long as the body is stiff enough. So you are not just making one axle worse, you are making the other better! Good video! I'd love to hear your thoughts on horizontally mounted chassis dampers like the SARD motion control beam.
I have a Pontiac Grand Prix. The suspension is exactly like a 68-72 GM A-Body (Chevelle, GTO, 442, GS). I did the poly bushings, cut one full coil from the front coils, added a 1" rear bar and gas shocks. The MOST PROFOUND result was replacing the stock 1" front bar with a 1-1/4 bar from a WS-6 Trans Am. The car rides firm but not harsh. However, it corners very well. It is fun to drive in twisty roads. The last change I need to make is to install a bump steer correction kit.
Excellent presentation, sir. To your point, I have posted the fastest time at many SCCA autocross events over the past 14 seasons while running either an NB Miata with no rear sway bar, or a Subaru WRX with no front sway bar. I actually won the D Street class regionals in my 2017 WRX with no front sway bar and bone stock springs/ dampers. I only tuned the car balance with alignment, tire pressure, my right foot, and lots of second-hand knowledge from books about Autocross suspension theory (Dan Watson is one of my favs). After looking through your videos tonight, I’m looking certainly forward to adding your book to my collection next.
When VW worked to set their Nurburgring lap times for the MK2 Golf It was faster around the track with no front sway bar. The rear doesn't run a separate sway bar but the rear axle itself is effectively one.
As the wise man once said: "even the worst suspension can be improved by preventing it from operating." Mostly necessary due to roll center and how high cars are. If you have a low car, or one with low center of gravity (EV?) may not be necessary? As the owner of a string of VW cars I always found it hilarious I was undoing the semi-independent trailing arm rear suspension. It's also neat when the torsion beam can house a splined torsion bar of varying specifications, without needing any linkages.
A rear sway bar was my first modification to my car, it sharpened the handling on my FWD car in a lovely way. After that every other suspension and wheel change just compounded the sharpness in a complimentary way. Best value/dollar modification that is noticeable right away in my opinion.
Fitting a stiffer sway bar at the rear on my normal cars has always made them just 2x more enjoyable to drive. They are boring cars by default, but this has always been the minimum for what I would change to my FWD super understeery cars.
This is a very easy to understand yet highly educational video, I’ve known how a stiffer rear sway bar can be beneficial for fwd cars for more rear rotation but never knew the true reasoning behind this. Thank you for making this, you’ve gained a sub 😁
Lovely video, I intend on getting into motor racing be it time attack or wheel to wheel in IPRA or similar, these videos are amazing to watch. Thank you for the time you take to educate.
Bought 2 of your books: One on aerodynamics and the other on argumentation & logical persuasion. Good stuff. I know you're not a fan of F1 and motor racing, but I forgive you 😉
Legit the best video about swaybars. Not hard when most are just "fit my sponsors product" but you deliver again. I have applied a bunch of things you cover and friends with more 'sporty' feeling cars (JCW Mini, Civic on coilovers etc) struggle for grip as soon as the surface isn't perfect and New Zealand roads need club rally type setups
I will now be sharing this with everyone who asks about the first mod on a car. I changed both on my stinger, mostly because the stock swaybars are fixed bracket units, but I did stiff setting rear and soft front to get the same effect you are preaching. The change to a floating bracket alone made the ride more compliment to bumpy roads, and the stiffer bar in rear pulled the balance just slightly to oversteer. Great breakdown!!!
Extremely nice video. I am building a drift E30 and i have fitted a rear sway bar (stock) because it wasn't choosed on the initial car. I have also fitted an inline 6 engine instead of the inline 4 it had and not changed anything about the front sway bar yet. I will try driving the car without sway bar in the rear as in drifting you want all the available traction on the rear. Thanks for your nice videos. Greetings from Greece!
I had a 2014 Toyota Prius and adding the TRD rear sway bar was a game changer. The car felt so much less floaty when changing lanes around the speed limit. It took corners surprisingly well!
There is another use for sway bars in handling too. Helping with reversing a turn. From my own experimentation, mostly in computer simulations, I totally agree. When I'm tuning a car, and dialing in the handling, usually I adjust only one end at a time unless both ends are radically off from what they should be. While I tend to like running the softest suspension and sway bars that will allow good handling, I have noticed that having less roll stiffness tends to have a negative impact on the balance of a car when transitioning right from a turn in one direction to a turn in the other direction. For relatively smooth race tracks that have tight windy bits with no strait in between turns of opposing directions, I tend to retune the balance with stiffer sway bars. I adjust them both stiffer together in order to maintain the balance of the car while reducing the time it takes for the car to settle out of the corner. This can, as pointed out in the video, make the car more skatey throughout most of the track, but if you offset the minimal time lost through simple turns by dramatically improving the time through a technical bit, it can be worth it. But again, as soft as you can go while getting the job done. If anyone wants to weigh in with something to expound on this, please feel free. This is just from my experience learning to tune in simulators like LFS(Live For Speed) which provides great freedom to experiment with the suspension. I find that what Julian Edgar said in the video to be true, and it fits my experience as stated above.
Sway bars almost seem too easy, but when you experience the before and after, it seems ridiculous not to do it first. Great explanation! Interested in buying your book:)
Glad I found this video. I've read on the Honda Fit forum I frequent that this mod makes a world of difference for our plucky little hatches and I can't wait to buy mine.
Have done a bit of experimenting with the Chevy Cruze and autocross racing. Car started racing on stock suspension, then eibach lowering springs, then bolted a stiffening element to the rear twist beam, then got Koni yellow shocks for the rear, then got rear spring stuffers (rubber between coils) and finally the car began to rotate in the turns with 8 psi higher rear tire pressures vs front. This became my daily driver setup when not racing. The next incremental improvement [for autocross times] are the stiff spring option ISC coilovers, with 12k front and 10k rear springs, rear motion ratio 0.66. It rides terrible and gets into a harmonic on some roads while traveling at freeway speeds which bucks me like a bull ride. The car more easily rotates on the race track with less difference in rear vs. front tire pressure and less body roll. This season has more mods. I ran the calcs and got a set of 6.7k front springs to mate with the 10k rear springs giving a calculated frequencies of 1.9 front and 2.1 rear to try and achieve flat ride. The front shocks will be replaced with the standard ISC valving. Because of the soft front springs, I opted to get both the front and rear [adjustable] sway bars, front bar logic is to reduce body roll from the softer springs.
Yep. I live in Brazil and we don't have easy access to performance stuff, everything is either too expensive or or outright impossible to find. I did the sway bar first in my Fiat Uno. The Uno is the first global car Fiat has ever made, released back in 1983. Here in Brazil it was sold from 1984 to 2013, only stopping production cuz airbags and ABS became mandatory in 2014 up cars. From 1997 and above the Uno became the cheapest car one coumd buy, lacked any luxury or performance. But up to 1996 there were fancier models and even sportive models like the Uno Turbo, one of the coolest hot hatches you could get in Brazil and Europe in the early 90s. Mine is a 2001 model, so a cheap, boring, economic car. That until I bought the sway bar from a Uno Turbo and installed in mine, it instantly begun handling like a kart lol. Since then I've given it a bigger engine, gigantic brakes and excelent tires, Recaro seats and so on. (It's way better than a Uno Turbo now) But yeah, the best bang for buck upgrade was the sway bar. Truly night and day difference! Since then I've upgraded my brother's mk4 Golf with sway bars from the R32 lol. And also my parent's very boring, very mundane Logan (sold here as a Renault, but actually a Dacia elsewhere). Here in Brazil they made a hot hatch version of the Sandero, simply called Sandero R.S. Actually tuned by the french Renault R.S division, it had beter brakes, insane tires, completely overhauled suspension, etc. Since the Logan is just a sedan version of the Sandero, I purchased the sway bar from the Sandero R.S and installed it in the Logan. Easily the best thing I ever did, it used to roll so much it was scary taking the highway with it. Now it stays put and I've chasen much better, much stronger cars around the mountain roads we have here. Hahaha
This is incredible, thank you!! I just bought some cheap coilvers to stiffen up my pillowy soft suspension, but it understeers badly too. Assuming the new parts don't fix that, i see a sway bar in my future!
It was great info. Clear and concise as always. Good reassurance because I was building on information from racing sims up until this point and was not 100% sure this change is a great idea for the road. Anyways I have a Suzuki Swift/Cultus hatchback from 1997 which has quite noticable understeer in roundabouts even at normal speeds. These 1.0l models were not fitted with any sway bars and only the saloons and gti-s have one at the rear. So I sourced one from a saloon but had to realize the mounting points are not present on the underbody of the hatchback. At least now I go into the welding phase more confidently that it will have the desired effect and the modification will not have to be reverted.
I dont think what youre experiencing is understeer but... if you really want it then change the sway bar. Youre certainly not going to make it any worse thats for sure :D
Thank you for saying this. This rings very true for us in the bmw community - i see alot of people putting very stiff springs on their car. These aftermarket coilovers: ruin ride quality compromise chassis in suspension mounting points (in particular this exacerbates issues on e46 and e36 3er chassis) sometimes cost far more than oe options provide minimal handling improvements over factory sport suspension options. But when you bring up that an upgraded antiroll bar will make a bigger difference you are shut down and told you dont have an understanding and that the coilovers are "worth it" - I dont know what is causing this, potentially marketing by coilover manufacturers. The other belief is that lower = better handling. It just doesn't but that's another issues.
I think the lower is better thing comes from modern race cars producing more downforce the closer they are to the floor, which obviously doesn't matter even slightly in a normal car context.
I think many people want coilovers because the ride height is adjustable to their aesthetic preferences. It's less about the performance improvement, and more about replacing old stuff with new and making the car look better. If you have a beat-up old E36, a cheap set of coilovers will still be an improvement from stock 30-year-old blown out shocks and springs. Personally, I would rather keep it simple with new shocks and lowering springs, but I understand the appeal.
Really good video and info. Nice and succinct but gave me a much better insight into how swaybars affect dynamics. I appreciated how you mentioned the limitations of stiffness as a general solution too. Felt like enough info to make help make decisions with less chance of wasting money and time on something that ends up not actually fixing problems or making the whole system perform worse. Might have to pick up that book hey? And see what else you've written. While I'm happy enough following the pack with modding my cars I've always admired the guys who aren't just kind of cargo culting a set of proven upgrades and truly understand the decisions they're making or the more complex projects they can take on. But it's always seemed pretty impenetrable to me, just as far as access to info and theory, so a couple of good books might be the right place to get started.
Obviously I recommend my own books but there's truly very little thorough and expert-vetted information out there. Just lots of noise and misinformation... especially if you're modifying an unusual car.
I was driving on ice tracks last winter. Got annoyed by the tremendous oversteer my E30 318is offered. Removed link from the rear sway bar and car immediately felt faster. Thinking about improving front tire contact patch later. Previous owner has increased caster, which means that the front wheels tilt heavily with greater steering angles and in the slow sharp turns the car understeered before and still does, by a lot. Of course the limited slip in the back is probably also to blame, but compared to my brothers E36, my car is a lot slower in the sharpies and we used the same tyres. It's nice to see that car videos are not all about wide wheels, turbos and lowering, someone actually speaks about making cars better. Thanks for giving the insight. Greatly appreciated.
@@JulianEdgar in most cases, I would agree. But my theory is that on flat ice with streetlegal studs and almost no body roll in slow sharp turns, any camber over stock most likely worsens contact patch or pressure on the studs. I can even see on the trackday photos how unevenly loaded the front tyres were in the tight corners. Having tried similar cars which did not understeer as much, I'm fairly sure that extra caster is the problem.
@@JulianEdgar Increased -ve camber on the inside tire will decrease it's grip (as the camber is actually +ve as far as the tire is concerned) which could come into play at low-speed, low-G pivoting kind of motions like hairpins or an ice track. E30 has quite high caster, so it could be a real factor. Camber will also make longitudinal grip worse, which will just exaggerate the issues if braking is applied.
I too have an e30 but with the e36 328i engine and 3.46 plate lsd. The standard sport dampers, very slightly lowered springs, increased front caster with ever so slight toe out made my car very quick on our rough roads. Sometimes literally driving around other cars that had too low and stiff suspension. My one issue was low to mid speed corner exit oversteer. I thought it might be a combination of too much torque and relative light weight but now I'm thinking about trying to tweak the balance via the anti roll bars... Thank you for sharing your knowledge and experience everyone 🙏
Yep, been doing that for a while. Got my last one to understeer with throttle input, and oversteer without. it could be balanced with just a little gas.
Amazing advice more people need to hear. It's almost better to be modifying on a budget at first, as you look to really effective solutions like sway bars before someone can sell you a set of expensive coilovers or suspension 'stage' tuning kits that make any modern car far too stiff,, too low, and disconnected from the road.
Sway bars are good and easy modifications, just be careful. On one of my cars I went from a hollow 19 to a hollow 25mm in the rear (from the sportier trim level of the car) and it snapped the mounting point off the subframe after some excited driving. After re welding it stronger its snapped in new places about 5 more times and now I have to drop the subrame and reinforce everything for it lol. but if you have a car that isnt made of cheese it shouldnt be an issue
Thank you for the wonderful and concise video. I can only speak from off-road community, but this kind of clears up why disconnecting front sway bar can improve cross axle articulation, more effective than removing both sway bars. I also read above in comments that a pair of stiffer rear coils achieve similar effect to a stiffer rear sway bar, but can it potentially improve cross-axle articulation, on 5 link solid rear axle vehicle? If you draw a simple diagram, coil springs on a 5 link solid rear axle are also pushing down opposite wheel as the fulcrum is the other wheel.
@@JulianEdgarjust the answer I was looking for! In the states it is getting harder and harder to find a customs shop that ... Ya know... Does actual custom work.
Oright, I think I understand. It will apply to people that have an issue with the way a car is driving, which I had a slight complain with my Honda back in the day where in original form it was way too tail happy, after I fitted my coilovers it drove way better and much more predictable but now it had a little bit too much understeer sometimes, nothing that I couldn't control but it sometimes was a little issue. I was messing with coilover dampening in front to counter it, but never felt any massive difference. Sway bar was on my list as many used to says it makes the car drive even better, but no one ever really went deeper into why that's the case. I have a brief knowledge on car suspension but far from expert. Now this helps a lot. My MX5 currently has the same issue on stock suspension, front will start understeering, with it it's a little different tho cuz often it will oversteer after correcting it, makes it fun, but it's an odd behaviour. Obviously it's an old ass car with 20yr old bushes and so on, but worth knowing this for the future, especially when I'll be setting up my 370Z. Thankfully that doesn't have any of these issues, it grips hard and is definitely a little more on the oversteer side, but very controlable and pretty predictable. Again that's on stock suspension, and I don't push it that hard so I didn't run into limits of the oem setup, I do want stiffer setup tho, purely for the driver feel, also to reduce the body roll as it's a little more than I would like. I would love to see next video on stuff like suspension dampening and spring rates in greater detail, I may even get your book, or an audio book if that will be available!
Thanks for the video! Any chance you have a playlist explaining racing setups? This sway bar video helped me understand it incredibly easily, I still don't understand a lot of the setup options in Racing simulators like ACC and iRacing.
Yes this man knows what he is talking about. Followed his suggestion on a Volvo xc70 witch is very soft and has a lot of understeer from the factory. Replaced rear from 20 to 25mm and also replaced front from 24 to 26mm. Amazing difference. Of course loosing a bit traction in off-road and full out suspension travel limit, but not hardly any noticeable compared to gained feel of handling ferormance👍
@@LateralTwitlerLT Well yes, but why was there the need to upgrade the front swaybar then? Perhaps he felt the car was rolling too much as well? If he ONLY wanted to reduce the understeered then there'd be no need to upgrade the front also. Was just gonna ask him about it.
Great informative video 👍 To somewhat bolster your explanation, but also contradict the point about kits, is that kits I’ve seen seem to significantly increase the size of one bar over the other with aim (I assume) of the manufacturer to restore the balance and reduce undesirable driving characteristics. Assuming the manufacturers actually R&D their products, surely when sold as a set, it’s in their interest to deliver a neutral/balanced feel, unless of course they’re relying on uneducated/inexperienced customers. Again, great explanation and not disagreeing with your overall message 🙂
On dirt track cars, some people on a tight budget outright remove the front sway bar to get more over steer. They handle like crap but it does seem to work
I never knew-probably due to inexperience-exactly why many road cars have both front and rear sway bars if having only one could compensate for the steering imbalance after designing in flat-ride spring rates. The drawback of having a sway bar is that the left and right sides become coupled, reducing grip on one-wheel bump scenarios. One thought is that having both sway bars might be necessary because designing the control arm nodes to have enough camber gain and enough travel while hitting ride frequency requirements could be challenging, so the easy way out would be to add roll stiffness by putting stiff sway bars. Another idea is that higher roll stiffness feels more responsive; thus, it appeals to younger folks.
@JulianEdgar great video. Does your book cover how to measure sway bar torsion to compare to spring rates? Very few sway bar manufacturers include that data and the diameter in mm can be very misleading. I am also looking for a good resource on spring rate to sway bar torsion ratios. I have seen some cars at track days running extremely stiff springs and no sway bars. I assume there is a balance there being missed.
I think there needs to be a follow up on how stiff suspension interacts with stiff or soft. Such as what happens if you have radically soft suspension on stiff anti sway bars.
For once, I changed only rear sway bar in my RX-8 to make it more oversteer to compensate with front tires wear(low budget for tires) but it made the car wanted to steer all the time. I guess in already balance car from the factory, u need both sway bars with adjustable function would be best.
awesome video as usual! any chance you can do a similar one on Strut-Bars? They were all the rage when I was modding cars 20ish years ago, but I could never get a straight answer on what they were actually achieving (further than looking hot when you open the bonnet)
With the new swaybar links that have the balljoint style ends, I just cut them off all together. With the rough rural roads we live on those links, even the best we can find, last less than a year.
Hi Julian, this is the first video I’ve come across of yours and it’s very informative just the type of channel I’ve been looking for. I’ve got a fwd car which I’ve had under steer issues with. I fitted a rear sway bar and am still having issues. Would completely removing my front sway bar be of any benefit? Thanks
That's usually a bit of a radical move, but you could do so for some careful testing (assuming that the sway bar doesn't help locate the wheels, of course).
@@JulianEdgar I may try see if the base model of my vehicle has a thinner sway bar in the front and try that first. Very much enjoyed the video mate I’ll be watching from now on.
Is there a quantifiable manner with which we can find the necessary increase to the sway bar stiffness to achieve the desired handling characteristics? Additionally, how does one go about getting a custom stiffness sway bar made? I've just stumbled upon your channel and I find your presentation style very informative and concise. Looking forward to your book
Yes it can be quantified however you will need so much accurate information (spring rates, motion ratios of springs and sway bars, centre of gravity height) and use a car simulation model, that it's not worth it. You get a custom bar made at any place that makes custom bars - often also spring manufacturers. Sway bar stiffness goes up as the fourth power of diameter. A educated guess is a good starting point. Happy to do that if you give me details on your car eg f/r weight distribution, existing bar sizes front and back, FWD, RWD or AWD, standard or modified springs.
@@JulianEdgar Is there a formulaic method to get this approximation? I am currently trying to make the car fully roadworthy first before making any changes😅, although I greatly appreciate the offer.
Been thinking exactly this. I've got an understeery Golf, and learned about ARBs. Every video I watched, changing the rear ARB looks super easy. Why don't more people talk about it?
(1) Because they're companies that want to sell lots of expensive stuff. (2) Or because they're people who don't understand much about suspension but who have learned lots of technical sounding terms. For relatively modern cars with stiff damping and stiff springs (like they nearly all have), a single sway bar change is usually enough to radically improve road car handling.
My car came with no sway bars, but an optional front sway bar was available from factory. It tends slightly towards understeer, so I was thinking a factory front sway bar and aftermarket (slightly stiffer) rear sway bar would be a good solution. This video seems to agree^^
Also regarding what you said about stiffness not equaling good handling, I recently upgraded from BC racing coilovers to quality KYB dampers and lowering springs. Far softer, but far better handling.
Thank you for making this video. I read stuff about the rear sway bar, and this clears things up even more. Just one question. Is there a huge difference between a rear sway bar and a front strut bar? Thanks.
A rear stabilizer and a front strut bar don't perform the same function and are incomparable entirely. One is a spring, the other is an elastokinematic component.
Edgar, Excellent video as always. I am looking forward to your next book. However, I wonder how I could know if I have too soft sway bars or excessively stiff bars? For example, If I fit very stiff sway bars to both front and rear, this might not change understeer/oversteer characteristics, but it should affect handling somehow, because they are too stiff, right?
My car is plowing straight in winter. It's really annoying me, sometimes I even handbake a bit to help it turn. I thought that I can fit a thicker rear sway bar from different trim, but this is already the thickest there was. But I never thought about going softer in front, because I hate body roll. There were some thinner ones on this model. After this video, I am thinking maybe I will also give it a go with the softer front. Maybe i will like it.
Hello! It’s amazing that this video was posted right before my experiment with sway bars! Thank you for sharing such a key point information! I’m was about to try solid sway bars instead of tubular on my Audi A3. It’s tuned from the factory to understeer 22.5x3.5 front and 20.7x2.8. I’ve found that vw sharan has 24mm solid front and 20mm solid rear. Passat r36 has 23.6 solid front and 21.7x3.6. Golf VI R 4wd 22 solid front 21.7x3.6 rear Sirocco R FWD 23.6x3.5 front 21.7x 3.6 rear Is there much difference between solid and tubular in terms of torsional resistance? What set up would you try? Thank you so much for your time and help! P.S. Can’t wait to get the new book!
Since it’s a popular platform for projects so I’ll share some information on the topic: standard Golf/TDI/A3: 21.7x3.0 or 22.5x.3.5 / 18.5x2.5 or 19.6x2.6 or 20.7x2.8 Scirocco: 21.7x3.0 or 22.5x.3.5 / 20.7x2.8 or 21.7x3.0 TT-RS quattro: 22 mm solid / 18.5 x 2.5 mm A3 Ambition/S-Line: 22,5 x 3,5 / 20,7 x 2,8 (FWD) Golf V GTI: 23,6 x 3,5 / 21,7 x 3,0 Golf V R32: 22,0 solid / 21,7 x 3,0 (4-motion) Golf VI GTI: 23,6 x 3,5 / 21,7 x 3,0 PR-0BF or 21,7 x 3,6 PR-0BM (DCC?) Golf VI R: 22,0 solid / 21,7 x 3,6 (4-motion) Scirocco R: 23,6 x 3,5 / 21,7 x 3,6 Touran 170 PS: 23,0 solid / 21,7 x 3,0 Passat R36: 23,6 solid / 21,7 x 3,6 (4-motion) Sharan 2011 on: 24.0 mm solid / 20.0 mm solid after market (almost all are solid): H&R TT Quattro: 24 / 22 mm incl. TT-RS H&R 'small': 26 / 22 mm Eibach AntiRoll: 26 / 23 mm KW clubsport: 26 / 23 mm (made by Eibach) VW Racing: 26 / 23 mm (made by Eibach, discontinued) ECS: 26 / 23 mm H&R 'big': 28 / 24 mm (AWE used to sell also a H&R 28 mm rear bar) H&R 4-motion/Quattro: 24 / 26 mm 034Motorsport: 25.4 mm rear only Autotech: 25 / 25 mm (tube/hollow; reliability issues) Whiteline: 24 / 24 mm (3-way adjustable) Neuspeed: 25 / 25 mm (tube/hollow; also 28 mm rear avail.; reliability issues) BFI/Stabila: -- / 25 mm rear only (different version for FWD and AWD) Hotchkis: 27 / 27 mm (tube/hollow) APR: 27 / 27 mm (tube/hollow; made by Hotchkis) BSH: -- / 27 mm (3-way) rear only
The stiffness difference between hollow and solid isn't as much as you might think. I'd go for a tubular rear bar that is a bit bigger in diameter than the existing one. 21.7 x 3.0 or 3.6?
@@JulianEdgar I'd disagree. This depends on the wall thickness and overall specifications of the bar. Some racing bars, if made solid, would produce wheelrates 100,000 N/m~ higher and this is AFTER installation stiffness, motion ratio and all that. A more accurate way to present it is that "The stiffness difference between OEM solid and hollow bars isn't as much as you might think". Usually the higher OD more sporty hollow bars will still be stiffer than the lower OD less sporty solid bar. Sometimes a higher OD solid bar might even be softer, if the torsion bar arm is very long, due to for example being a modification for an AWD version of the platform and so on. You need to do the math.
Great video mate I've just subscribed. Could you do a video on the most beneficial mods you can do to your car for street use? Ive watched your video on modifying air boxes I just don't know if you'd consider them properly beneficial for any car? Thanks
I have a 2013 Audi s4, and like most audis they tend to understeer because of the engine being so far forward. By far the best upgrade ive done was a larger rear sway bar, and it will even get a little sideways now if i push it hard enough.
I've wondering to make my own rear swaybar for my mazda 2, but I don't know how to calculate what stiffness I need. I can just copy the design of a manufacturer, but as a junior engineer I'm more interested in how to design a proper anti roll bar. Also I find that my car has pretty neutral handling so I don't want to ruin it putting a stiff sway bar at the back.
You will find popery designing a rear sway bar to be immensely difficult. eg you will need C of G height, suspension roll centre heights, stiffness of springs, motion ratios of both the springs and proposed bar, etc. Better to copy a similar car as a starting point.
it's very hard (pun intended) to really overdo it, but maybe with a rear torsion beam you won't need as much. take measurements of the existin setup and calculate what you need to double the stiffness. I went with 4x stiffer myself
I agree with the physics explanation except that I think this effect is only transient, meaning it happens while the weight transfer is happening during and after changes in cornering. At steady state during a turn I don't think the weight on the inside and outside tires would be different with or without sway bars. This is just working off of my intuition on physics.
You'd better buy the book when it comes out - there's a detailed explanation in it of how sway bars change weight transfer on the front and rear (it doesn't change on the inner and outer tyre pairs). And it's not a transient thing.
I would argue the best thing for fixing understeer, would be camber. Going from stock to 3 degrees of camber up front will make a much bigger difference than altering the sway bar. Also, it depends on the car/package it comes with, but generally wider wheels/tires and camber should be the first mod someone does (in my opinion for track pace).
Only if you also want poorer braking, poorer traction (in a FWD) and greater inside tyre wear (road car). None of which occur with changing lateral weight transfer via sway bars!
@@JulianEdgar the amount of time lost in braking is massively trumped by increased cornering speed… but yes in a fwd you would compromise traction due to reduced contact patch when unloaded. However, running more camber allows you to have higher minimum corner speed and no one is getting back on throttle when the steering is straight. Your outside wheel will be loaded so id still think you’d have more traction on a track. Personally, I don’t have much fwd track experience, but the few people that run fwd track cars here all run -3+ degrees up front on track. Also, sure you’ll wear the inside a little more, but the comparison on track isn’t even close.
Not sure why you assume everything is about the track. About 1:1000 the number of people who track their cars versus drive on the street and want a good handling car. Running increased neg front camber will increase front cornering grip, but why not actually make use of the grip that all four tyres *already have available*? That is the point of the video, after all.
call me crazy but im running a 93 subaru legacy (inside a 1980 BRAT chassis) with no swaybars front or rear and it handles really well with surprisingly little body roll. they did not come with rear swaybars from the factory and are known to understeer so i figured it wouldnt hurt to test drive it without the front one installed and sure enough it makes a ton of mechanical grip! so heres a question: do different suspension setups cause more or less body roll? like is macpherson going to resist roll more than a solid axle for example? or am i only getting away with this cause my cg is super low?
Thank you sir! This was very helpful! What if the car has 50/50 power distribution? (2022 WRX) Also, is a stiffer sway bar makes the ride quality worse? The car is already very stiff.
@JulianEdgar thx for the fast Awnser. As I read the answer I litterly could see how. But as far as I know there are no aftermarket kits for a 206. Just the dampers. And to let make one in Germany is very expensive, just for the paper.
@@timtrial3971 Ive done that before, funnily enough that's how I wrote off my 97 Camry. It was fun while it lasted and atleast no one died, pretty bad crash though
@herniagaming I only lfb in hillclimbs and rally sprints. You don't need to on downhill. I rarely get to do it. My truck has the steering column in way
And also if you add "struct bards" to the rear and from will improve everything. i seen some new brand new vehicles from dealers already putting them in the from struts but i am nt sure if they also put it in the rear.
@@JulianEdgarI will say both because at the end of the day is all about to get rid of that "roll over" i have not try it yet but a friend of mine told me that the struct bars did a huge change on his car. i will try it on my car but the dealer or oem from toyota does not exist so i have to find a 3rd party company to see if some one out there makes them for my car. I need to try them first and see if is true what they say. but i know for a fact that the sway bar and the sway bar links and the sway bar bushing when you replaced them with brand new ones you see a huge change basically the car feels again like when it was brand new the handling the the roll over is not there or is way less.
Great video! I have a question about this topic, I have a bmw e82 135i, which has very little (and not adjustable) camber at the front wheels and zero camber gain, putting the tires in a disadvantageous position when cornering hard, basically loading only the outside of the tire (which wears much faster than the outside). Some people in the forums suggest that fitting a stiffer front sway bar the reduction in body roll allows the tires to have better contact on the ground thus enabling them to produce more grip than with a softer bar. Do you think this could be the truth?
I've got a getz that unsersteers like a pig. Is there an easy way to stiffen the rear torsion beam, or add a sway bar (which it didn't come with)? Or would it be easier just to buy stiffer springs for the rear? Any advice appreciated. I enjoy your videos!
This is something I’ve tried to tell people for years. Easily one of the best bang for buck modifications you can make to your car. Every time I modify a car, one of my first purchases is an upgraded rear anti-roll bar.
Yes, me too. Even before I change tyres...
It's good for smooth roads... It makes the ride much rougher on bad roads though. The double edged sword of stiffness.
It does take away some comfort. Depending on where you live, If comfort is the priority, don't do it.
Otherwise it definitely helps in cornering handling and stability
I don't think you watched the full video?
@@JulianEdgar no way 😳. Thx again. 🙏 I hope there is a German translation of ur book.
I thought that was common sense, it’s pretty well known in 4x4 when you raise the car more than 3 inches to not just lose all steering or rolling over in the first sharp turn
Funny story, this trick is how I used to beat the pants off of people in the old video game Gran Tourismo.
It was billed as a "driving simulator" and bragged about a realistic physics engine. That's what got me interested in it, and I wasn't disappointed.
In that old game, sway bars and lightening were the under appreciated modifications that could turn a boring compact into a consistent winner.
My general tactic for cheapest results was to fit the "racing" level bars, both front and rear. These offered the greatest adjustment range, and I'd start with the front on full soft, and the rear midway. I'd consistently beat far more powerful cars with little effort. It would rotate very fast in low speed turns, fairly neutral in faster turns, and allowed full power on corner exits a lot earlier than my overpowered, understeering, rear drive competitors.
Works in real life too.
Gran Turismo series still going strong at its 7th release
babe wake up julian egdar just posted a new video
But what did 'babe' say?
@@JulianEdgar she asked if it was an aerodynamic testing video and she went back to sleep due to the resulting answer😔
The ND Mazda MX-5 might be one of the exceptions among modern performance cars, very soft suspension setup and pretty good handling balance from the factory.
It's a well-designed car - there's no issue with soft suspension giving good handling.
It also benefits from 50-50 weight distribution and very low overall weight :)
I would guess these factors allow it to have a soft suspension and maintain good dynamics
This is what I come to CZcams for
It's amazing how many people do not understand this. Thanks for making this video. And hopefully some of the internet "experts" will watch this.
Saw the thumbnail and knew I would like the presentation
This is the exact problem I'm fighting, and while I found the answer myself through hours of research I'm glad to have the confidence of this video backing it.
Any good references you’ve found in your research?
It's even better than that! It's true that the sway bar increases outer wheel load on the axle it's mounted at, reducing that axle's cornering grip.
Additionally, it also increases wheel load on the diagonally opposed wheel on the other axle, as long as the body is stiff enough.
So you are not just making one axle worse, you are making the other better!
Good video! I'd love to hear your thoughts on horizontally mounted chassis dampers like the SARD motion control beam.
Yes in my upcoming book I cover how swaybars work in much more detail, including the diagonal weight transfer.
@@JulianEdgar When do you think that will be published? :)
It's largely finished - just waiting on final materials and feedback from expert reviewers. But that takes time - perhaps 3 months?
@@JulianEdgar thanks for the reply!
@@JulianEdgar Good video. I'm looking forward to the book. Cheers for all of your Autospeed content too - great stuff.
I have a Pontiac Grand Prix. The suspension is exactly like a 68-72 GM A-Body (Chevelle, GTO, 442, GS). I did the poly bushings, cut one full coil from the front coils, added a 1" rear bar and gas shocks. The MOST PROFOUND result was replacing the stock 1" front bar with a 1-1/4 bar from a WS-6 Trans Am. The car rides firm but not harsh. However, it corners very well. It is fun to drive in twisty roads. The last change I need to make is to install a bump steer correction kit.
Excellent presentation, sir. To your point, I have posted the fastest time at many SCCA autocross events over the past 14 seasons while running either an NB Miata with no rear sway bar, or a Subaru WRX with no front sway bar.
I actually won the D Street class regionals in my 2017 WRX with no front sway bar and bone stock springs/ dampers. I only tuned the car balance with alignment, tire pressure, my right foot, and lots of second-hand knowledge from books about Autocross suspension theory (Dan Watson is one of my favs).
After looking through your videos tonight, I’m looking certainly forward to adding your book to my collection next.
When VW worked to set their Nurburgring lap times for the MK2 Golf It was faster around the track with no front sway bar. The rear doesn't run a separate sway bar but the rear axle itself is effectively one.
As the wise man once said: "even the worst suspension can be improved by preventing it from operating." Mostly necessary due to roll center and how high cars are. If you have a low car, or one with low center of gravity (EV?) may not be necessary? As the owner of a string of VW cars I always found it hilarious I was undoing the semi-independent trailing arm rear suspension. It's also neat when the torsion beam can house a splined torsion bar of varying specifications, without needing any linkages.
Idk what those words mean but I’m assuming you took the springs out and are just letting control arms and body flex be your suspension
Hahaha that quote is great.
A rear sway bar was my first modification to my car, it sharpened the handling on my FWD car in a lovely way. After that every other suspension and wheel change just compounded the sharpness in a complimentary way. Best value/dollar modification that is noticeable right away in my opinion.
Julian, great to see you posting again.
I really respect your advice.
Fitting a stiffer sway bar at the rear on my normal cars has always made them just 2x more enjoyable to drive. They are boring cars by default, but this has always been the minimum for what I would change to my FWD super understeery cars.
What a breath of fresh air. Easy to understand and easy to do. Thank you.
Nice good commonsense approach to car suspension mods
Great explanation! Getting an upgraded rear sway bar for my Golf GTI was a game changer.
This is a very easy to understand yet highly educational video, I’ve known how a stiffer rear sway bar can be beneficial for fwd cars for more rear rotation but never knew the true reasoning behind this. Thank you for making this, you’ve gained a sub 😁
Lovely video, I intend on getting into motor racing be it time attack or wheel to wheel in IPRA or similar, these videos are amazing to watch. Thank you for the time you take to educate.
Bought 2 of your books: One on aerodynamics and the other on argumentation & logical persuasion.
Good stuff. I know you're not a fan of F1 and motor racing, but I forgive you 😉
Cannot be explained better. So clear.
A pleasure 😊
I'll watch again ❤
I'm glad I found this gem of a channel. Thank you!
Welcome!
I love studying car suspensions. You got a new subscriber 🤙
Legit the best video about swaybars. Not hard when most are just "fit my sponsors product" but you deliver again.
I have applied a bunch of things you cover and friends with more 'sporty' feeling cars (JCW Mini, Civic on coilovers etc) struggle for grip as soon as the surface isn't perfect and New Zealand roads need club rally type setups
As an ignorant learner, this video concisely educated me on what a sway ar IS, DOES, and HOW it does it. Thanks sir. 🫡
Thank you for your work. I look forward to more of your content.
Thank you
I will now be sharing this with everyone who asks about the first mod on a car. I changed both on my stinger, mostly because the stock swaybars are fixed bracket units, but I did stiff setting rear and soft front to get the same effect you are preaching. The change to a floating bracket alone made the ride more compliment to bumpy roads, and the stiffer bar in rear pulled the balance just slightly to oversteer. Great breakdown!!!
Extremely nice video. I am building a drift E30 and i have fitted a rear sway bar (stock) because it wasn't choosed on the initial car. I have also fitted an inline 6 engine instead of the inline 4 it had and not changed anything about the front sway bar yet. I will try driving the car without sway bar in the rear as in drifting you want all the available traction on the rear. Thanks for your nice videos. Greetings from Greece!
Brilliant overview.
Brilliant advice, love it.
I had a 2014 Toyota Prius and adding the TRD rear sway bar was a game changer. The car felt so much less floaty when changing lanes around the speed limit. It took corners surprisingly well!
You wouldn't believe the crap I've heard about sway bars... "it turns independent suspension into a live axle" is my personal favourite
There is another use for sway bars in handling too. Helping with reversing a turn.
From my own experimentation, mostly in computer simulations, I totally agree. When I'm tuning a car, and dialing in the handling, usually I adjust only one end at a time unless both ends are radically off from what they should be.
While I tend to like running the softest suspension and sway bars that will allow good handling, I have noticed that having less roll stiffness tends to have a negative impact on the balance of a car when transitioning right from a turn in one direction to a turn in the other direction. For relatively smooth race tracks that have tight windy bits with no strait in between turns of opposing directions, I tend to retune the balance with stiffer sway bars. I adjust them both stiffer together in order to maintain the balance of the car while reducing the time it takes for the car to settle out of the corner. This can, as pointed out in the video, make the car more skatey throughout most of the track, but if you offset the minimal time lost through simple turns by dramatically improving the time through a technical bit, it can be worth it. But again, as soft as you can go while getting the job done.
If anyone wants to weigh in with something to expound on this, please feel free. This is just from my experience learning to tune in simulators like LFS(Live For Speed) which provides great freedom to experiment with the suspension. I find that what Julian Edgar said in the video to be true, and it fits my experience as stated above.
I learnt something today... thank you sir
This is really informative and interesting. Thanks for the advice!
Glad it was helpful!
Sway bars almost seem too easy, but when you experience the before and after, it seems ridiculous not to do it first. Great explanation! Interested in buying your book:)
Glad I found this video. I've read on the Honda Fit forum I frequent that this mod makes a world of difference for our plucky little hatches and I can't wait to buy mine.
Yes, little FWDs usually benefit a great deal from a rear stiffer bar.
Too powerful, I’ve learned it through Forza Motorsports 7 and since then I am trying to tell people but it is soo underrated!
Thank you sir for the education🎉
Have done a bit of experimenting with the Chevy Cruze and autocross racing. Car started racing on stock suspension, then eibach lowering springs, then bolted a stiffening element to the rear twist beam, then got Koni yellow shocks for the rear, then got rear spring stuffers (rubber between coils) and finally the car began to rotate in the turns with 8 psi higher rear tire pressures vs front. This became my daily driver setup when not racing.
The next incremental improvement [for autocross times] are the stiff spring option ISC coilovers, with 12k front and 10k rear springs, rear motion ratio 0.66. It rides terrible and gets into a harmonic on some roads while traveling at freeway speeds which bucks me like a bull ride. The car more easily rotates on the race track with less difference in rear vs. front tire pressure and less body roll.
This season has more mods. I ran the calcs and got a set of 6.7k front springs to mate with the 10k rear springs giving a calculated frequencies of 1.9 front and 2.1 rear to try and achieve flat ride. The front shocks will be replaced with the standard ISC valving. Because of the soft front springs, I opted to get both the front and rear [adjustable] sway bars, front bar logic is to reduce body roll from the softer springs.
Amazing video! you deserve so many more subscribers
Thank you
Awesome video man! Good info! :) Liked and subbed!
Will probably try that, nice idea 💡
Yep. I live in Brazil and we don't have easy access to performance stuff, everything is either too expensive or or outright impossible to find.
I did the sway bar first in my Fiat Uno. The Uno is the first global car Fiat has ever made, released back in 1983. Here in Brazil it was sold from 1984 to 2013, only stopping production cuz airbags and ABS became mandatory in 2014 up cars.
From 1997 and above the Uno became the cheapest car one coumd buy, lacked any luxury or performance.
But up to 1996 there were fancier models and even sportive models like the Uno Turbo, one of the coolest hot hatches you could get in Brazil and Europe in the early 90s.
Mine is a 2001 model, so a cheap, boring, economic car.
That until I bought the sway bar from a Uno Turbo and installed in mine, it instantly begun handling like a kart lol. Since then I've given it a bigger engine, gigantic brakes and excelent tires, Recaro seats and so on. (It's way better than a Uno Turbo now)
But yeah, the best bang for buck upgrade was the sway bar. Truly night and day difference!
Since then I've upgraded my brother's mk4 Golf with sway bars from the R32 lol.
And also my parent's very boring, very mundane Logan (sold here as a Renault, but actually a Dacia elsewhere).
Here in Brazil they made a hot hatch version of the Sandero, simply called Sandero R.S. Actually tuned by the french Renault R.S division, it had beter brakes, insane tires, completely overhauled suspension, etc.
Since the Logan is just a sedan version of the Sandero, I purchased the sway bar from the Sandero R.S and installed it in the Logan.
Easily the best thing I ever did, it used to roll so much it was scary taking the highway with it. Now it stays put and I've chasen much better, much stronger cars around the mountain roads we have here. Hahaha
This is incredible, thank you!! I just bought some cheap coilvers to stiffen up my pillowy soft suspension, but it understeers badly too. Assuming the new parts don't fix that, i see a sway bar in my future!
A stiffer rear bar - or you could fit stiffer rear springs.
It was great info. Clear and concise as always. Good reassurance because I was building on information from racing sims up until this point and was not 100% sure this change is a great idea for the road.
Anyways I have a Suzuki Swift/Cultus hatchback from 1997 which has quite noticable understeer in roundabouts even at normal speeds. These 1.0l models were not fitted with any sway bars and only the saloons and gti-s have one at the rear. So I sourced one from a saloon but had to realize the mounting points are not present on the underbody of the hatchback. At least now I go into the welding phase more confidently that it will have the desired effect and the modification will not have to be reverted.
I dont think what youre experiencing is understeer but... if you really want it then change the sway bar. Youre certainly not going to make it any worse thats for sure :D
Thank you for saying this. This rings very true for us in the bmw community - i see alot of people putting very stiff springs on their car. These aftermarket coilovers:
ruin ride quality
compromise chassis in suspension mounting points (in particular this exacerbates issues on e46 and e36 3er chassis)
sometimes cost far more than oe options
provide minimal handling improvements over factory sport suspension options.
But when you bring up that an upgraded antiroll bar will make a bigger difference you are shut down and told you dont have an understanding and that the coilovers are "worth it" - I dont know what is causing this, potentially marketing by coilover manufacturers.
The other belief is that lower = better handling. It just doesn't but that's another issues.
Yes, coilovers are just the current fashion. I don't know why.
@@JulianEdgar very glad i found your channel. i plan to purchase some of your books and watch the rest of your content.
I think the lower is better thing comes from modern race cars producing more downforce the closer they are to the floor, which obviously doesn't matter even slightly in a normal car context.
I think many people want coilovers because the ride height is adjustable to their aesthetic preferences. It's less about the performance improvement, and more about replacing old stuff with new and making the car look better. If you have a beat-up old E36, a cheap set of coilovers will still be an improvement from stock 30-year-old blown out shocks and springs. Personally, I would rather keep it simple with new shocks and lowering springs, but I understand the appeal.
awesome video!
Really good video and info. Nice and succinct but gave me a much better insight into how swaybars affect dynamics. I appreciated how you mentioned the limitations of stiffness as a general solution too. Felt like enough info to make help make decisions with less chance of wasting money and time on something that ends up not actually fixing problems or making the whole system perform worse.
Might have to pick up that book hey? And see what else you've written. While I'm happy enough following the pack with modding my cars I've always admired the guys who aren't just kind of cargo culting a set of proven upgrades and truly understand the decisions they're making or the more complex projects they can take on. But it's always seemed pretty impenetrable to me, just as far as access to info and theory, so a couple of good books might be the right place to get started.
Obviously I recommend my own books but there's truly very little thorough and expert-vetted information out there. Just lots of noise and misinformation... especially if you're modifying an unusual car.
great channel! great video!
I was driving on ice tracks last winter. Got annoyed by the tremendous oversteer my E30 318is offered. Removed link from the rear sway bar and car immediately felt faster.
Thinking about improving front tire contact patch later. Previous owner has increased caster, which means that the front wheels tilt heavily with greater steering angles and in the slow sharp turns the car understeered before and still does, by a lot. Of course the limited slip in the back is probably also to blame, but compared to my brothers E36, my car is a lot slower in the sharpies and we used the same tyres.
It's nice to see that car videos are not all about wide wheels, turbos and lowering, someone actually speaks about making cars better.
Thanks for giving the insight. Greatly appreciated.
Increased castor gives increased dynamic camber that should reduce understeer, not increase it.
@@JulianEdgar in most cases, I would agree. But my theory is that on flat ice with streetlegal studs and almost no body roll in slow sharp turns, any camber over stock most likely worsens contact patch or pressure on the studs. I can even see on the trackday photos how unevenly loaded the front tyres were in the tight corners. Having tried similar cars which did not understeer as much, I'm fairly sure that extra caster is the problem.
Yes that sounds right for a very low friction surface.
@@JulianEdgar Increased -ve camber on the inside tire will decrease it's grip (as the camber is actually +ve as far as the tire is concerned) which could come into play at low-speed, low-G pivoting kind of motions like hairpins or an ice track.
E30 has quite high caster, so it could be a real factor.
Camber will also make longitudinal grip worse, which will just exaggerate the issues if braking is applied.
I too have an e30 but with the e36 328i engine and 3.46 plate lsd.
The standard sport dampers, very slightly lowered springs, increased front caster with ever so slight toe out made my car very quick on our rough roads. Sometimes literally driving around other cars that had too low and stiff suspension.
My one issue was low to mid speed corner exit oversteer. I thought it might be a combination of too much torque and relative light weight but now I'm thinking about trying to tweak the balance via the anti roll bars...
Thank you for sharing your knowledge and experience everyone 🙏
Yep, been doing that for a while. Got my last one to understeer with throttle input, and oversteer without. it could be balanced with just a little gas.
Amazing advice more people need to hear. It's almost better to be modifying on a budget at first, as you look to really effective solutions like sway bars before someone can sell you a set of expensive coilovers or suspension 'stage' tuning kits that make any modern car far too stiff,, too low, and disconnected from the road.
Excellent
My rear saybar is out for deleivery and this video pops up. Can't wait to install it.
The algorithm hard at work!
Brilliant!
Sway bars are good and easy modifications, just be careful. On one of my cars I went from a hollow 19 to a hollow 25mm in the rear (from the sportier trim level of the car) and it snapped the mounting point off the subframe after some excited driving. After re welding it stronger its snapped in new places about 5 more times and now I have to drop the subrame and reinforce everything for it lol. but if you have a car that isnt made of cheese it shouldnt be an issue
Thank you for the wonderful and concise video. I can only speak from off-road community, but this kind of clears up why disconnecting front sway bar can improve cross axle articulation, more effective than removing both sway bars. I also read above in comments that a pair of stiffer rear coils achieve similar effect to a stiffer rear sway bar, but can it potentially improve cross-axle articulation, on 5 link solid rear axle vehicle? If you draw a simple diagram, coil springs on a 5 link solid rear axle are also pushing down opposite wheel as the fulcrum is the other wheel.
Great video ty.
Excellent video as usual.
Glad you enjoyed it
@@JulianEdgar By the way, how did you go about getting a sway bar made? I'm guessing the choice of steel grade is as important as fitment.
Went to a company that makes them - very easy. I used Signature Swaybars.
@@JulianEdgarjust the answer I was looking for! In the states it is getting harder and harder to find a customs shop that ... Ya know... Does actual custom work.
Oright, I think I understand. It will apply to people that have an issue with the way a car is driving, which I had a slight complain with my Honda back in the day where in original form it was way too tail happy, after I fitted my coilovers it drove way better and much more predictable but now it had a little bit too much understeer sometimes, nothing that I couldn't control but it sometimes was a little issue. I was messing with coilover dampening in front to counter it, but never felt any massive difference. Sway bar was on my list as many used to says it makes the car drive even better, but no one ever really went deeper into why that's the case. I have a brief knowledge on car suspension but far from expert. Now this helps a lot. My MX5 currently has the same issue on stock suspension, front will start understeering, with it it's a little different tho cuz often it will oversteer after correcting it, makes it fun, but it's an odd behaviour. Obviously it's an old ass car with 20yr old bushes and so on, but worth knowing this for the future, especially when I'll be setting up my 370Z. Thankfully that doesn't have any of these issues, it grips hard and is definitely a little more on the oversteer side, but very controlable and pretty predictable. Again that's on stock suspension, and I don't push it that hard so I didn't run into limits of the oem setup, I do want stiffer setup tho, purely for the driver feel, also to reduce the body roll as it's a little more than I would like.
I would love to see next video on stuff like suspension dampening and spring rates in greater detail, I may even get your book, or an audio book if that will be available!
Thanks for the video! Any chance you have a playlist explaining racing setups? This sway bar video helped me understand it incredibly easily, I still don't understand a lot of the setup options in Racing simulators like ACC and iRacing.
Can you list the main set-up parameters? I can then at least tell you if my forthcoming book will help.
Yes this man knows what he is talking about.
Followed his suggestion on a Volvo xc70 witch is very soft and has a lot of understeer from the factory.
Replaced rear from 20 to 25mm and also replaced front from 24 to 26mm.
Amazing difference. Of course loosing a bit traction in off-road and full out suspension travel limit, but not hardly any noticeable compared to gained feel of handling ferormance👍
Why'd you stiffen the front if you already have understeer? Put back your original one and it'll be even better.
@@nesmio7378 He stiffened the front - yes, but it got _softened_ in *relation* to the rear sway bar, and so it overall reduces understeer.
@@LateralTwitlerLT Well yes, but why was there the need to upgrade the front swaybar then? Perhaps he felt the car was rolling too much as well? If he ONLY wanted to reduce the understeered then there'd be no need to upgrade the front also. Was just gonna ask him about it.
Great informative video 👍
To somewhat bolster your explanation, but also contradict the point about kits, is that kits I’ve seen seem to significantly increase the size of one bar over the other with aim (I assume) of the manufacturer to restore the balance and reduce undesirable driving characteristics.
Assuming the manufacturers actually R&D their products, surely when sold as a set, it’s in their interest to deliver a neutral/balanced feel, unless of course they’re relying on uneducated/inexperienced customers.
Again, great explanation and not disagreeing with your overall message 🙂
3:29 looks like the Dunlop SP Sport Max 060+ tyre I just fitted to my Freelander 2 today 😅
On dirt track cars, some people on a tight budget outright remove the front sway bar to get more over steer. They handle like crap but it does seem to work
I never knew-probably due to inexperience-exactly why many road cars have both front and rear sway bars if having only one could compensate for the steering imbalance after designing in flat-ride spring rates. The drawback of having a sway bar is that the left and right sides become coupled, reducing grip on one-wheel bump scenarios.
One thought is that having both sway bars might be necessary because designing the control arm nodes to have enough camber gain and enough travel while hitting ride frequency requirements could be challenging, so the easy way out would be to add roll stiffness by putting stiff sway bars.
Another idea is that higher roll stiffness feels more responsive; thus, it appeals to younger folks.
@JulianEdgar great video. Does your book cover how to measure sway bar torsion to compare to spring rates? Very few sway bar manufacturers include that data and the diameter in mm can be very misleading.
I am also looking for a good resource on spring rate to sway bar torsion ratios. I have seen some cars at track days running extremely stiff springs and no sway bars. I assume there is a balance there being missed.
Yes, the new book covers these ideas.
I think there needs to be a follow up on how stiff suspension interacts with stiff or soft. Such as what happens if you have radically soft suspension on stiff anti sway bars.
For once, I changed only rear sway bar in my RX-8 to make it more oversteer to compensate with front tires wear(low budget for tires) but it made the car wanted to steer all the time. I guess in already balance car from the factory, u need both sway bars with adjustable function would be best.
awesome video as usual! any chance you can do a similar one on Strut-Bars? They were all the rage when I was modding cars 20ish years ago, but I could never get a straight answer on what they were actually achieving (further than looking hot when you open the bonnet)
Strut bars basically do little / nothing on any modern cars.
With the new swaybar links that have the balljoint style ends, I just cut them off all together. With the rough rural roads we live on those links, even the best we can find, last less than a year.
Hi Julian, this is the first video I’ve come across of yours and it’s very informative just the type of channel I’ve been looking for. I’ve got a fwd car which I’ve had under steer issues with. I fitted a rear sway bar and am still having issues. Would completely removing my front sway bar be of any benefit? Thanks
That's usually a bit of a radical move, but you could do so for some careful testing (assuming that the sway bar doesn't help locate the wheels, of course).
@@JulianEdgar I may try see if the base model of my vehicle has a thinner sway bar in the front and try that first. Very much enjoyed the video mate I’ll be watching from now on.
Is there a quantifiable manner with which we can find the necessary increase to the sway bar stiffness to achieve the desired handling characteristics? Additionally, how does one go about getting a custom stiffness sway bar made? I've just stumbled upon your channel and I find your presentation style very informative and concise. Looking forward to your book
Yes it can be quantified however you will need so much accurate information (spring rates, motion ratios of springs and sway bars, centre of gravity height) and use a car simulation model, that it's not worth it. You get a custom bar made at any place that makes custom bars - often also spring manufacturers. Sway bar stiffness goes up as the fourth power of diameter. A educated guess is a good starting point. Happy to do that if you give me details on your car eg f/r weight distribution, existing bar sizes front and back, FWD, RWD or AWD, standard or modified springs.
@@JulianEdgar Is there a formulaic method to get this approximation? I am currently trying to make the car fully roadworthy first before making any changes😅, although I greatly appreciate the offer.
No there isn't. Too many variables.
Been thinking exactly this. I've got an understeery Golf, and learned about ARBs. Every video I watched, changing the rear ARB looks super easy. Why don't more people talk about it?
(1) Because they're companies that want to sell lots of expensive stuff. (2) Or because they're people who don't understand much about suspension but who have learned lots of technical sounding terms.
For relatively modern cars with stiff damping and stiff springs (like they nearly all have), a single sway bar change is usually enough to radically improve road car handling.
My car came with no sway bars, but an optional front sway bar was available from factory. It tends slightly towards understeer, so I was thinking a factory front sway bar and aftermarket (slightly stiffer) rear sway bar would be a good solution. This video seems to agree^^
Also regarding what you said about stiffness not equaling good handling, I recently upgraded from BC racing coilovers to quality KYB dampers and lowering springs. Far softer, but far better handling.
Yes it's a fallacy that stiff = good handling on a road car.
Thank you for making this video. I read stuff about the rear sway bar, and this clears things up even more. Just one question. Is there a huge difference between a rear sway bar and a front strut bar?
Thanks.
Yes, one makes a huge difference and the other typically a trivial difference.
A rear stabilizer and a front strut bar don't perform the same function and are incomparable entirely. One is a spring, the other is an elastokinematic component.
@@ArchOfficial Ah I see... Thanks for clarifying.
Edgar,
Excellent video as always. I am looking forward to your next book. However, I wonder how I could know if I have too soft sway bars or excessively stiff bars? For example, If I fit very stiff sway bars to both front and rear, this might not change understeer/oversteer characteristics, but it should affect handling somehow, because they are too stiff, right?
Too stiff bars give skatey handling in slippery conditions and poor ride quality over one-wheel bumps.
@@JulianEdgar Thank you very much
My car is plowing straight in winter. It's really annoying me, sometimes I even handbake a bit to help it turn. I thought that I can fit a thicker rear sway bar from different trim, but this is already the thickest there was. But I never thought about going softer in front, because I hate body roll. There were some thinner ones on this model.
After this video, I am thinking maybe I will also give it a go with the softer front. Maybe i will like it.
Hello! It’s amazing that this video was posted right before my experiment with sway bars!
Thank you for sharing such a key point information!
I’m was about to try solid sway bars instead of tubular on my Audi A3. It’s tuned from the factory to understeer 22.5x3.5 front and 20.7x2.8. I’ve found that vw sharan has 24mm solid front and 20mm solid rear.
Passat r36 has 23.6 solid front and 21.7x3.6.
Golf VI R 4wd 22 solid front 21.7x3.6 rear
Sirocco R FWD 23.6x3.5 front 21.7x 3.6 rear
Is there much difference between solid and tubular in terms of torsional resistance? What set up would you try? Thank you so much for your time and help!
P.S. Can’t wait to get the new book!
Since it’s a popular platform for projects so I’ll share some information on the topic:
standard Golf/TDI/A3: 21.7x3.0 or 22.5x.3.5 / 18.5x2.5 or 19.6x2.6 or 20.7x2.8
Scirocco: 21.7x3.0 or 22.5x.3.5 / 20.7x2.8 or 21.7x3.0
TT-RS quattro: 22 mm solid / 18.5 x 2.5 mm
A3 Ambition/S-Line: 22,5 x 3,5 / 20,7 x 2,8 (FWD)
Golf V GTI: 23,6 x 3,5 / 21,7 x 3,0
Golf V R32: 22,0 solid / 21,7 x 3,0 (4-motion)
Golf VI GTI: 23,6 x 3,5 / 21,7 x 3,0 PR-0BF or 21,7 x 3,6 PR-0BM (DCC?)
Golf VI R: 22,0 solid / 21,7 x 3,6 (4-motion)
Scirocco R: 23,6 x 3,5 / 21,7 x 3,6
Touran 170 PS: 23,0 solid / 21,7 x 3,0
Passat R36: 23,6 solid / 21,7 x 3,6 (4-motion)
Sharan 2011 on: 24.0 mm solid / 20.0 mm solid
after market (almost all are solid):
H&R TT Quattro: 24 / 22 mm incl. TT-RS
H&R 'small': 26 / 22 mm
Eibach AntiRoll: 26 / 23 mm
KW clubsport: 26 / 23 mm (made by Eibach)
VW Racing: 26 / 23 mm (made by Eibach, discontinued)
ECS: 26 / 23 mm
H&R 'big': 28 / 24 mm (AWE used to sell also a H&R 28 mm rear bar)
H&R 4-motion/Quattro: 24 / 26 mm
034Motorsport: 25.4 mm rear only
Autotech: 25 / 25 mm (tube/hollow; reliability issues)
Whiteline: 24 / 24 mm (3-way adjustable)
Neuspeed: 25 / 25 mm (tube/hollow; also 28 mm rear avail.; reliability issues)
BFI/Stabila: -- / 25 mm rear only (different version for FWD and AWD)
Hotchkis: 27 / 27 mm (tube/hollow)
APR: 27 / 27 mm (tube/hollow; made by Hotchkis)
BSH: -- / 27 mm (3-way) rear only
The stiffness difference between hollow and solid isn't as much as you might think. I'd go for a tubular rear bar that is a bit bigger in diameter than the existing one. 21.7 x 3.0 or 3.6?
@@JulianEdgar I'd disagree. This depends on the wall thickness and overall specifications of the bar. Some racing bars, if made solid, would produce wheelrates 100,000 N/m~ higher and this is AFTER installation stiffness, motion ratio and all that.
A more accurate way to present it is that "The stiffness difference between OEM solid and hollow bars isn't as much as you might think".
Usually the higher OD more sporty hollow bars will still be stiffer than the lower OD less sporty solid bar. Sometimes a higher OD solid bar might even be softer, if the torsion bar arm is very long, due to for example being a modification for an AWD version of the platform and so on. You need to do the math.
Great video mate I've just subscribed. Could you do a video on the most beneficial mods you can do to your car for street use?
Ive watched your video on modifying air boxes I just don't know if you'd consider them properly beneficial for any car? Thanks
It depends on what outcomes you're chasing.
@@JulianEdgar If we're talking purely performance gains. Like do you try and optimize the airbox on every vehicle you own?
For performance gains, intake and exhaust are cheapest and easiest. The flow restrictions of both are easily measured on the road, too.
@@JulianEdgar Could you do a video on exhausts and how to make good gains? I'd be very interested to watch it
I have a 2013 Audi s4, and like most audis they tend to understeer because of the engine being so far forward. By far the best upgrade ive done was a larger rear sway bar, and it will even get a little sideways now if i push it hard enough.
Cheapest and easiest way to improve handling is with a proper alignment. More negative camber and less toe in. Makes a huge difference.
Actually, makes quite a minor difference compared to altering a sway bar.
I've wondering to make my own rear swaybar for my mazda 2, but I don't know how to calculate what stiffness I need. I can just copy the design of a manufacturer, but as a junior engineer I'm more interested in how to design a proper anti roll bar. Also I find that my car has pretty neutral handling so I don't want to ruin it putting a stiff sway bar at the back.
You will find popery designing a rear sway bar to be immensely difficult. eg you will need C of G height, suspension roll centre heights, stiffness of springs, motion ratios of both the springs and proposed bar, etc. Better to copy a similar car as a starting point.
it's very hard (pun intended) to really overdo it, but maybe with a rear torsion beam you won't need as much. take measurements of the existin setup and calculate what you need to double the stiffness. I went with 4x stiffer myself
I agree with the physics explanation except that I think this effect is only transient, meaning it happens while the weight transfer is happening during and after changes in cornering. At steady state during a turn I don't think the weight on the inside and outside tires would be different with or without sway bars.
This is just working off of my intuition on physics.
You'd better buy the book when it comes out - there's a detailed explanation in it of how sway bars change weight transfer on the front and rear (it doesn't change on the inner and outer tyre pairs). And it's not a transient thing.
Tyres are also really easy and very noticable.
Perhaps watch my recent video on why you shouldn't change the tyres first.
@@JulianEdgar I definately will, I really love your videos, super informative.
I would argue the best thing for fixing understeer, would be camber. Going from stock to 3 degrees of camber up front will make a much bigger difference than altering the sway bar.
Also, it depends on the car/package it comes with, but generally wider wheels/tires and camber should be the first mod someone does (in my opinion for track pace).
Only if you also want poorer braking, poorer traction (in a FWD) and greater inside tyre wear (road car). None of which occur with changing lateral weight transfer via sway bars!
@@JulianEdgar the amount of time lost in braking is massively trumped by increased cornering speed… but yes in a fwd you would compromise traction due to reduced contact patch when unloaded. However, running more camber allows you to have higher minimum corner speed and no one is getting back on throttle when the steering is straight. Your outside wheel will be loaded so id still think you’d have more traction on a track. Personally, I don’t have much fwd track experience, but the few people that run fwd track cars here all run -3+ degrees up front on track.
Also, sure you’ll wear the inside a little more, but the comparison on track isn’t even close.
Not sure why you assume everything is about the track. About 1:1000 the number of people who track their cars versus drive on the street and want a good handling car. Running increased neg front camber will increase front cornering grip, but why not actually make use of the grip that all four tyres *already have available*? That is the point of the video, after all.
call me crazy but im running a 93 subaru legacy (inside a 1980 BRAT chassis) with no swaybars front or rear and it handles really well with surprisingly little body roll. they did not come with rear swaybars from the factory and are known to understeer so i figured it wouldnt hurt to test drive it without the front one installed and sure enough it makes a ton of mechanical grip! so heres a question: do different suspension setups cause more or less body roll? like is macpherson going to resist roll more than a solid axle for example? or am i only getting away with this cause my cg is super low?
I feel like i just walked into a lecture lol. Distinguished man in a suit with a powerpoint talking about sway bars
Yep, deliberate.
Thank you sir! This was very helpful!
What if the car has 50/50 power distribution? (2022 WRX) Also, is a stiffer sway bar makes the ride quality worse? The car is already very stiff.
Start with what the car is doing that you want to fix. Stiffer bars make ride quality worse.
@@JulianEdgarall right! Thanks!
Great another upgrade I cant do. Torsion bar life 😢
You can fit swaybars to cars with torsion bar suspension.
Sir ,thank you for this great explanation.
Now iam just curios as an 206 driver. What would you do on an Torisionbar, in this case rear axel.
Sway bars can be fitted to torsion beam rear axles.
@JulianEdgar thx for the fast Awnser. As I read the answer I litterly could see how. But as far as I know there are no aftermarket kits for a 206. Just the dampers. And to let make one in Germany is very expensive, just for the paper.
www.aleksracing.com/hardrace-7923-rear-sway-bar-peugeot-206
Fwd with a slight rear bias would be fun I reckon
It is.
left foot braking or lifting off the throttle in the corner will reduce the rear grip and increase oversteer
@@timtrial3971 Ive done that before, funnily enough that's how I wrote off my 97 Camry. It was fun while it lasted and atleast no one died, pretty bad crash though
@herniagaming I only lfb in hillclimbs and rally sprints. You don't need to on downhill. I rarely get to do it. My truck has the steering column in way
And also if you add "struct bards" to the rear and from will improve everything. i seen some new brand new vehicles from dealers already putting them in the from struts but i am nt sure if they also put it in the rear.
Strut bars basically do little / nothing on any modern cars.
@@JulianEdgarI will say both because at the end of the day is all about to get rid of that "roll over" i have not try it yet but a friend of mine told me that the struct bars did a huge change on his car. i will try it on my car but the dealer or oem from toyota does not exist so i have to find a 3rd party company to see if some one out there makes them for my car. I need to try them first and see if is true what they say. but i know for a fact that the sway bar and the sway bar links and the sway bar bushing when you replaced them with brand new ones you see a huge change basically the car feels again like when it was brand new the handling the the roll over is not there or is way less.
Strut bars basically do little / nothing on any modern cars. Waste your money as you wish.
Great video! I have a question about this topic, I have a bmw e82 135i, which has very little (and not adjustable) camber at the front wheels and zero camber gain, putting the tires in a disadvantageous position when cornering hard, basically loading only the outside of the tire (which wears much faster than the outside).
Some people in the forums suggest that fitting a stiffer front sway bar the reduction in body roll allows the tires to have better contact on the ground thus enabling them to produce more grip than with a softer bar.
Do you think this could be the truth?
Yes, the only real reason to limit body roll is to reduce camber loss on the outside wheel.
Thanks for sharing.
Where did you source the custom sway bar?
Signature Swaybars
@@JulianEdgar thanks
What about active sway bars, like in the Xantia Activa? That's probably one great technology not that much used....
Covered in my book on the history of suspension - www.amazon.com/Car-Suspension-over-years-handling/dp/B09CRNQB9P
Hello Julian, on the video you said that you made yourself your own sway bar for your MG car, could you show us how to DIY for our own cars?
No, I said I had it custom made for me. Still quite cheap.
Put a rear sway bar on my Toyota Tundra and it was a major improvement.
I've got a getz that unsersteers like a pig. Is there an easy way to stiffen the rear torsion beam, or add a sway bar (which it didn't come with)? Or would it be easier just to buy stiffer springs for the rear? Any advice appreciated. I enjoy your videos!
You can add a sway bar to a torsion beam rear axle.