Back in the day, on the classic WRX (up to 2000) one of the best mods to sort out the turn-in and power understeer was a thicker rear-sway bar and the so-called "anti-lift kit" which added front caster. I ran my car like that for years on road and track and it was an absolute weapon and I felt very little need to change anything more. Anyway, that was an interesting summary, and confirms everything I thought I knew about handling adjustments which is a relief! 🙂
Super useful basic video, and the way you categorise each 'type' of understeer is quite handy. And driving style is so important, you have to work with the car, not against it.
Hey mate a drive a FWD double wishbone honda (CU2). The cusco coilovers have quite a low recommended springrate in the rear compared to the back. 12kg / 5kg rear. Any reason why they'd recommend so low? Its a top spech street performance coilover and similar models have a slightly higher rear springrate. What do you think?
You'd better read the book. Quoting spring rates alone is pointless. Their actual stiffness depends on how they're mounted and how much weight acts through them.
@@PROofHAPPYWHEELSmotion ratio and wheel rate. The front and rear have different geometry. The rear is likely 1:1, while the front is closer to .65:1. Motion ratio is the ratio of how much the spring moved during compression compared to actual wheel movement. The further inboard of the hub, the more leverage the wheel has on the spring, so you need a higher spring rate. Wheel rate is the effective spring rate of the wheel and you can calculate it by using this: WR = MR^2 * Spring Rate. So assuming what I said was true for your car’s possible motion ratios: WR (rear) = 5k (since it’s 1:1) WR (front) = (.65)^2 * 12k = 5.07k This is just an example and not your car, but it may be close. An aspect I left out was angle, but it is mostly negligible for road cars since the spring and the wheel typically travel in the same plane (or very close).
Finally someone with both knowledge and common sense on the tube . I just watched a couple of his vids and ordered the book. Best part is his subtle warning about after market parts companies with marketing goals. Also, more is not always better, in fact more often it isn't.
Many years ago, I bought a Pontiac Fiero (mid-engine 2-seater), and was surprised to find it had noticeable understeer. GM outfitted them with a front sway bar, but no rear sway bar. And they also dialed in some understeer with the alignment. It would understeer until the front end got some grip, then it would snap oversteer. Not fun. So I installed a rear sway bar. That balanced out the handling, and made the car a lot more fun to drive.
Fascinating, fellow midship owner here ('84/'00 MR2) & the anti-sways are what I preach to other owners when they're looking to dial in the handling characteristics of their cars; From your example sounds as if the Fieros handling dynamic is *very* similar to the AW11 MR2 (also did not have a rear anti-roll from factory)
Other features that could cause understeer: - Limited slip differential - Dynamic toe/camber changes due to kinematics (bump steer etc.) or elasto-kinematics (bushings) - Low rear chassis stiffness - Lowering too much and hitting the bump stops - Staggered tire sizes (wider rear tires) - Roll center height - Anti-geometry - Weight distribution - AWD torque distribution
I definitely agree with changing you driving style to reduce understeer. So many people are too quick to fit coilovers and wind them down. Then talk themselves into believing it's better than standard.
Thank you again Julian. Simply insightful as always. Be careful with that whole "change your driving style". If you think the trolls came out on the last video, woo boy. LoL..
Thank you for giving me the terminology to describe the execrable garbage scow handling of my mum's 2000 Accord. Sweet engine, abominable handling and horrifically uncomfortable entry/exit & seating for us normal sized North Americans. Hated that car.
RIght now i drive a Renault Megane, wonderfully developed car, tons of control everywhere. Right now i have completely stock suspension with only some 130€ lowering springs added. On Tarmac it has tons of turn in and responsiveness. On gravel it almost drives like an RWD car, just sharp turn in and it pulls a slide. In contrast to that i had Audi A4 years ago, it's stock suspension was absolutely terrible - the understeer was just endless and car was totally undrivable. I had many near crash experiences. Didnt matter whether i was driving on snow with studded tyres or on summer tyres on a dry racing track - it just didnt want to turn.
I've been watching your videos for around 4 months now, I have to say they're great! I've got a old school Suzuki baleno I daily drive and have a bit of cash I could chuck at her. I'm going to start with restoring the factory suspension (K&N shocks and K&N lowering springs, while also restoring all the bushes) then I'll asses the suspension and probably add a stiffer rear sway bar (factory front sway bar is larger diameter I assume to induce understeer.) after that I'll for for sticker tyres (the ones I've got are good but not great) and then I'll get back to you how well the changes I made have had on performance.
I've also found out that I have the same shifter as most Honda civics so I can get a pretty awesome shifter for the car... The only thing left after that would maybe be aerodynamics... Eh. Or what is more realistic, more power. Turbo I say... xD I'm down the rabbit hole for sure! Haha.
I drive a Saab 9000, it is front wheel drive and has very great feedback on its understeer, but whenever it goes understeer too much, induced oversteer from the rear axle turning would come in to ease it, the rear axle can turn a bit left and right, working with swaybar and panhard rod. It's pretty weird, I can see why many drivers don't like it, it discourages fun. lol
Julian, amazing video. Also we need video about alignment angles, specifically how different drivetrains react to toe in/toe out, camber in/out etc... Since I tried to do toe out on front axle (FWD car) although OEM spec was hard toe in and the car have literally transformed, steering got really sharp and car felt more nimble at city driving.
Alignment is difficult to make broad recommendations about because it changes so much when the car is in motion - bush deflection, body and suspension arm deflections. The book covers these deflections in a lot of detail and when you see what really occurs, you think - best done by on-road (or track) testing.
Hey Julian, thank you for sharing the content you have on youtube. I've watched many of your videos, and as a fellow insight owner, I've loved them. I was wondering if you could do a deep dive video that goes over each of the changes you've made to your insight, and what the results of each change was on the total system? I'd like to attempt to capture some of the "low hanging fruit" for aero improvement on a car that is already incredible.
I won't be doing any more videos on the Insight. However, all the Insight's modifications are covered in detail in my books - there's a complete book on the Insight, engine management modifications are covered in my book on engine management, suspension mods are covered in my books on suspension, aero mods in my book on aero, etc. www.amazon.com/stores/Julian-Edgar/author/B00C3MRYN4/allbooks
@@JulianEdgar Thank you for the reply. I was interested in all of that information being collated together in a single video, however I completely understand if that isn't the direction you want to take with your channel. I see you focused primarily on educating for how to modify any car, rather than one specific car, focusing on first principles instead of "copy this for a given result".
@@JulianEdgar ahh I see where the confusion may have come from. I was saying all of the information regarding the insight specifically, not the knowledge of everything you’ve ever done. I was thinking an insight specific video could probably be done in 30 min or less. Again, thank you for your time and I appreciate the link to your books. May need to pick up the one that focuses on aero modifications.
Not wanting to get stuck into you but if you honestly think I could cover in a 30 min video the Insight's aero (front undertray, rear undertray, Edgarwit air curtains, rear fins, rear wing, rear ducktail spoiler, rear airbrake); engine (new airbox, turbo, water/air intercooler, MoTeC engine management installation, MoTeC engine management on-road tuning, cam tuning, exhaust); MoTeC dash (custom set-up and install); steel suspension (new specific springs front and back, new rear dampers, rear anti roll bar); custom air suspension (selecting and installing new front air springs, new rear air springs, custom electronic control systems x 2, custom air supply system, custom front air reservoirs)... and I haven't finished.... well... (Maybe you didn't realise how heavily modified the car is?)
Is there a place where we can see all the books you have made? I've gotten the aerodynamic volumes 1 and 2 and have really loved the information and tests you've shown. I'd love to read more of your works and apply them to my builds in the future.
I've got a question about the Alfa 116 /161 chassis (Alfetta to Alfa 75). These cars are RWD with 50/50 weight distribution. The rear suspension has a deDion tube with coil springs, watts linkage and a sway bar. The front suspension has unequal length upper and lower a arms, torsion bars and a sway bar. On my own Alfa 75 I fitted a thicker aftermarket rear sway bar. I liked the results and didn't do anything else. Tires were P205/50R15 all around en.wikipedia.org/wiki/Alfa_Romeo_75 However the final evolution of this chassis was the limited edition Zagato ES30 SZ. This had the same deDion tube with coil springs rear suspension but no rear sway bar. The ES30 was one of the first street cars to break 1.00 G on the skip pad en.wikipedia.org/wiki/Alfa_Romeo_SZ Tires Pirelli P Zero tyres (front 205/55 ZR 16, rear 225/50 ZR 16) both the Alfa 75 and the ES had the same wheelbase 2,510 mm (98.8 in). How was the ES30 able to handle better than the Alfa 75 with no rear sway bar?
But the total amount of lateral grip possibile does not necessarily equal better handling, grip and handling are two seperate characteristics. A car with great grip can have a bad handling and a car with low grip can have sublime handling, these two variables don’t have to go hand in hand (although they can).
Think of a rear wheel drive car. The front wheels are rotating at the same speed as the rears but are transmitting no torque to the road… In other words, it’s how hard the tyre is pushing backwards on the road.
@@JulianEdgar Ok, I get that. To my understanding, different «torque splits» - like 40/60 or 65/35, are possible only with some slipping in transmission. Can you explain it a bit better?
@@JulianEdgar Cool! I just can’t stand uneven tire wear! Tires are expensiveeeee! Will I have the same effect if I widen the tires but remove the camber?
@@JulianEdgar yep! Springs are still good. Shock absorbers are replaced recently. The negative camber for the P1 generation Volvos have a negative camber of 0.7 (estimate) from the factory.
Would decreasing the psi of my tires in the front and increasing them in the back be a viable option to get rid of understeer? Or would that change another handling factor of my car?
Oversteer is undrivable at the limit (literally) so you're probably referring to neutral steer that can be tuned out into understeer via inputs. It's slow on track if that's the sustained cornering balance, but it can be funner and in some ways safer at low speeds like sport driving on canyons where many corners are rotation corners and you're not driving the car to the grip limit.
The amount of s2000 and MR2 snap oversteer videos Ive seen lol. I'd take understeer anyday over that. I feel like those cars would've benefitted from a fwd and AWD format
would you happen to have your books for sale anywhere but amazon? I don't particularly like to support amazon but I'd love to read and support your work!
Back in the day, on the classic WRX (up to 2000) one of the best mods to sort out the turn-in and power understeer was a thicker rear-sway bar and the so-called "anti-lift kit" which added front caster. I ran my car like that for years on road and track and it was an absolute weapon and I felt very little need to change anything more. Anyway, that was an interesting summary, and confirms everything I thought I knew about handling adjustments which is a relief! 🙂
I was just looking at this video to fix my WRX understeer while doing autoX
Super useful basic video, and the way you categorise each 'type' of understeer is quite handy. And driving style is so important, you have to work with the car, not against it.
Hey mate a drive a FWD double wishbone honda (CU2). The cusco coilovers have quite a low recommended springrate in the rear compared to the back.
12kg / 5kg rear. Any reason why they'd recommend so low? Its a top spech street performance coilover and similar models have a slightly higher rear springrate. What do you think?
You'd better read the book. Quoting spring rates alone is pointless. Their actual stiffness depends on how they're mounted and how much weight acts through them.
@@PROofHAPPYWHEELSmotion ratio and wheel rate. The front and rear have different geometry. The rear is likely 1:1, while the front is closer to .65:1.
Motion ratio is the ratio of how much the spring moved during compression compared to actual wheel movement. The further inboard of the hub, the more leverage the wheel has on the spring, so you need a higher spring rate.
Wheel rate is the effective spring rate of the wheel and you can calculate it by using this: WR = MR^2 * Spring Rate.
So assuming what I said was true for your car’s possible motion ratios:
WR (rear) = 5k (since it’s 1:1)
WR (front) = (.65)^2 * 12k = 5.07k
This is just an example and not your car, but it may be close. An aspect I left out was angle, but it is mostly negligible for road cars since the spring and the wheel typically travel in the same plane (or very close).
Finally someone with both knowledge and common sense on the tube . I just watched a couple of his vids and ordered the book. Best part is his subtle warning about after market parts companies with marketing goals. Also, more is not always better, in fact more often it isn't.
This bloke/chap/geeser is a national treasure.
Many years ago, I bought a Pontiac Fiero (mid-engine 2-seater), and was surprised to find it had noticeable understeer. GM outfitted them with a front sway bar, but no rear sway bar. And they also dialed in some understeer with the alignment. It would understeer until the front end got some grip, then it would snap oversteer. Not fun. So I installed a rear sway bar. That balanced out the handling, and made the car a lot more fun to drive.
Fascinating, fellow midship owner here ('84/'00 MR2) & the anti-sways are what I preach to other owners when they're looking to dial in the handling characteristics of their cars; From your example sounds as if the Fieros handling dynamic is *very* similar to the AW11 MR2 (also did not have a rear anti-roll from factory)
I’ve been following your channel for a few weeks now, and I’ve been learning so much! I can’t wait for your new book to come out!
Other features that could cause understeer:
- Limited slip differential
- Dynamic toe/camber changes due to kinematics (bump steer etc.) or elasto-kinematics (bushings)
- Low rear chassis stiffness
- Lowering too much and hitting the bump stops
- Staggered tire sizes (wider rear tires)
- Roll center height
- Anti-geometry
- Weight distribution
- AWD torque distribution
Yes indeed. But most of these are well down the list compared to those covered in the video, especially in what people can do about them.
great video, I like how much information you fit into these short videos! Very informative
Thank you
E28 on the front cover!? Love it. Great video.
The Lotus is freakin' epic, too. 😀
I definitely agree with changing you driving style to reduce understeer. So many people are too quick to fit coilovers and wind them down. Then talk themselves into believing it's better than standard.
Thank you again Julian. Simply insightful as always. Be careful with that whole "change your driving style". If you think the trolls came out on the last video, woo boy. LoL..
Thank you for giving me the terminology to describe the execrable garbage scow handling of my mum's 2000 Accord. Sweet engine, abominable handling and horrifically uncomfortable entry/exit & seating for us normal sized North Americans. Hated that car.
Yes, most manufacturers are excellent at chassis development. Small changes please
Worth emphasising I think. If the suspension is in good condition (dampers, bushes) some small tweaks are usually enough to get excellent results.
I look forward to purchasing the book
How much i would love to hear him talk about ride quality
It’s a full chapter in the book.
RIght now i drive a Renault Megane, wonderfully developed car, tons of control everywhere. Right now i have completely stock suspension with only some 130€ lowering springs added. On Tarmac it has tons of turn in and responsiveness. On gravel it almost drives like an RWD car, just sharp turn in and it pulls a slide.
In contrast to that i had Audi A4 years ago, it's stock suspension was absolutely terrible - the understeer was just endless and car was totally undrivable. I had many near crash experiences.
Didnt matter whether i was driving on snow with studded tyres or on summer tyres on a dry racing track - it just didnt want to turn.
There's a reason for the existence of the word "Audisteer"
3:50 A RWD car car also power understeer, especially in high speed corners
I've been watching your videos for around 4 months now, I have to say they're great! I've got a old school Suzuki baleno I daily drive and have a bit of cash I could chuck at her. I'm going to start with restoring the factory suspension (K&N shocks and K&N lowering springs, while also restoring all the bushes) then I'll asses the suspension and probably add a stiffer rear sway bar (factory front sway bar is larger diameter I assume to induce understeer.) after that I'll for for sticker tyres (the ones I've got are good but not great) and then I'll get back to you how well the changes I made have had on performance.
I've also found out that I have the same shifter as most Honda civics so I can get a pretty awesome shifter for the car... The only thing left after that would maybe be aerodynamics... Eh. Or what is more realistic, more power. Turbo I say... xD I'm down the rabbit hole for sure! Haha.
Sounds good.
I drive a Saab 9000, it is front wheel drive and has very great feedback on its understeer, but whenever it goes understeer too much, induced oversteer from the rear axle turning would come in to ease it, the rear axle can turn a bit left and right, working with swaybar and panhard rod.
It's pretty weird, I can see why many drivers don't like it, it discourages fun. lol
Julian, amazing video. Also we need video about alignment angles, specifically how different drivetrains react to toe in/toe out, camber in/out etc... Since I tried to do toe out on front axle (FWD car) although OEM spec was hard toe in and the car have literally transformed, steering got really sharp and car felt more nimble at city driving.
Alignment is difficult to make broad recommendations about because it changes so much when the car is in motion - bush deflection, body and suspension arm deflections. The book covers these deflections in a lot of detail and when you see what really occurs, you think - best done by on-road (or track) testing.
8:25 I think you meant "turn LATER" (late apex) to straighten the car earlier
I've been looking at TUV approved spring kits, and they are designed to not change the steering balance, so it feels better but isn't much.
Excited to hear you talk about oversteer in a possible next video?
Hey Julian, thank you for sharing the content you have on youtube. I've watched many of your videos, and as a fellow insight owner, I've loved them. I was wondering if you could do a deep dive video that goes over each of the changes you've made to your insight, and what the results of each change was on the total system? I'd like to attempt to capture some of the "low hanging fruit" for aero improvement on a car that is already incredible.
I won't be doing any more videos on the Insight. However, all the Insight's modifications are covered in detail in my books - there's a complete book on the Insight, engine management modifications are covered in my book on engine management, suspension mods are covered in my books on suspension, aero mods in my book on aero, etc. www.amazon.com/stores/Julian-Edgar/author/B00C3MRYN4/allbooks
@@JulianEdgar Thank you for the reply. I was interested in all of that information being collated together in a single video, however I completely understand if that isn't the direction you want to take with your channel. I see you focused primarily on educating for how to modify any car, rather than one specific car, focusing on first principles instead of "copy this for a given result".
Not sure if you’re serious? Such a video would go for dozens of hours. Anyway, the material is all published if you want to access it.
@@JulianEdgar ahh I see where the confusion may have come from. I was saying all of the information regarding the insight specifically, not the knowledge of everything you’ve ever done. I was thinking an insight specific video could probably be done in 30 min or less. Again, thank you for your time and I appreciate the link to your books. May need to pick up the one that focuses on aero modifications.
Not wanting to get stuck into you but if you honestly think I could cover in a 30 min video the Insight's aero (front undertray, rear undertray, Edgarwit air curtains, rear fins, rear wing, rear ducktail spoiler, rear airbrake); engine (new airbox, turbo, water/air intercooler, MoTeC engine management installation, MoTeC engine management on-road tuning, cam tuning, exhaust); MoTeC dash (custom set-up and install); steel suspension (new specific springs front and back, new rear dampers, rear anti roll bar); custom air suspension (selecting and installing new front air springs, new rear air springs, custom electronic control systems x 2, custom air supply system, custom front air reservoirs)... and I haven't finished.... well... (Maybe you didn't realise how heavily modified the car is?)
Great video! Would love to buy some of your books but the shipping to Europe is more than double than the actual book. 😔
They’re available from your nearest Amazon.
Is there a place where we can see all the books you have made? I've gotten the aerodynamic volumes 1 and 2 and have really loved the information and tests you've shown. I'd love to read more of your works and apply them to my builds in the future.
www.amazon.com/stores/Julian-Edgar/author/B00C3MRYN4/allbooks?ref=sr_ntt_srch_lnk_2&qid=1715063973&sr=1-2&isDramIntegrated=true&shoppingPortalEnabled=true
ill most likely buy the book
6:10 did you say Peugeot 306 GTI? 😂
I've got a question about the Alfa 116 /161 chassis (Alfetta to Alfa 75). These cars are RWD with 50/50 weight distribution. The rear suspension has a deDion tube with coil springs, watts linkage and a sway bar. The front suspension has unequal length upper and lower a arms, torsion bars and a sway bar.
On my own Alfa 75 I fitted a thicker aftermarket rear sway bar. I liked the results and didn't do anything else. Tires were P205/50R15 all around
en.wikipedia.org/wiki/Alfa_Romeo_75
However the final evolution of this chassis was the limited edition Zagato ES30 SZ. This had the same deDion tube with coil springs rear suspension but no rear sway bar. The ES30 was one of the first street cars to break 1.00 G on the skip pad
en.wikipedia.org/wiki/Alfa_Romeo_SZ
Tires Pirelli P Zero tyres (front 205/55 ZR 16, rear 225/50 ZR 16) both the Alfa 75 and the ES had the same wheelbase 2,510 mm (98.8 in).
How was the ES30 able to handle better than the Alfa 75 with no rear sway bar?
You need to look at the whole suspension eg including damper and spring rates. (And that’s assuming there were no geometry changes!)
But the total amount of lateral grip possibile does not necessarily equal better handling, grip and handling are two seperate characteristics.
A car with great grip can have a bad handling and a car with low grip can have sublime handling, these two variables don’t have to go hand in hand (although they can).
Any suggestions on where to buy your new book? I'd love to buy a copy.
It will be available from your local Amazon in a few months.
Chrome Orange Lotus for the win!
Yes, lovely pic by Tiit Saul
How a different «torque splits» are achieved if all four wheels are rotating with almost the same speed?
Think of a rear wheel drive car. The front wheels are rotating at the same speed as the rears but are transmitting no torque to the road… In other words, it’s how hard the tyre is pushing backwards on the road.
@@JulianEdgar Ok, I get that. To my understanding, different «torque splits» - like 40/60 or 65/35, are possible only with some slipping in transmission. Can you explain it a bit better?
are there any way to test & design intake manifold?
Yes of course.
When is ypur book available in the US?
Before August 2024
New video dropped🎉
Bbbbbbut fatter rear tires look good!
My car has rear negative camber from the factory. I bought a camber kit to straighten it out.
Thoughts on this?
If it had standard neg camber that was to provide more grip of the outer wheel in body roll during cornering.
@@JulianEdgar Cool! I just can’t stand uneven tire wear! Tires are expensiveeeee!
Will I have the same effect if I widen the tires but remove the camber?
Possibly. But no factory car has too much rear camber. Sure the springs haven't sagged?
@@JulianEdgar yep! Springs are still good. Shock absorbers are replaced recently.
The negative camber for the P1 generation Volvos have a negative camber of 0.7 (estimate) from the factory.
@@BoredGeese -0.7° is actually not very much for a factory car. My car from the factory has nearly double, around -1.3°.
Would decreasing the psi of my tires in the front and increasing them in the back be a viable option to get rid of understeer? Or would that change another handling factor of my car?
No, try it the other way around!
@@JulianEdgarreally? I always understood lower pressures to have more grip(within reason)
Just show a picture of an Audi.😂
Did someone say audisteer lol
Limp-home mode mandated inclusion LoL
You should watch this channel before modding your car...
Does me preffering oversteery car means I’m in a minority? Well thats kinda cool
Oversteer is undrivable at the limit (literally) so you're probably referring to neutral steer that can be tuned out into understeer via inputs.
It's slow on track if that's the sustained cornering balance, but it can be funner and in some ways safer at low speeds like sport driving on canyons where many corners are rotation corners and you're not driving the car to the grip limit.
@@ArchOfficial
Yep, thats pretty on the mark
The amount of s2000 and MR2 snap oversteer videos Ive seen lol. I'd take understeer anyday over that. I feel like those cars would've benefitted from a fwd and AWD format
would you happen to have your books for sale anywhere but amazon? I don't particularly like to support amazon but I'd love to read and support your work!
You can buy direct from me but unless you live in Australia, by the time you add postage, they will be much more expensive.