Suspension set up for road and track cars is not the same
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- čas přidán 20. 05. 2024
- Want a good road car? Don't set up its suspension for the track. (And, vice versa.) Buy the book now at www.amazon.com... or Amazon in your country.
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I find it odd that this is something people even get hung up on. You're pretty clear about it in your videos, and some of your books even have "road car" in the title.
The difference between a road setup and track setup has always been pretty intuitive to me. Suspension on a road car has to 1) maximise grip on unprepared surfaces, and 2) keep the inhabitants comfortable. A race car on rhe other hand only has one job, which is to maximise grip on a prepared surface. Any wonder the ideal setup is going to be vastly different.
Setting up a road car, I like to imagine it's gonna be used as a rally car. It's not going to rally of course, and an actual rally car will obviously be set up very differently, but it feels more intuitive that way. It needs to handle bumps and somewhat rough terrain, not send my spine into the headliner, and maximise grip over all of it. That was actually one of the main motivators for me to switch from BC coilovers back to KYB dampers and lowering springs. Not only the softer damping and spring rate, but the longer suspension travel. Makes a huge difference!
Just set camber to negative 5 degrees, caster to maximum, then weld the suspension solid, every driving god P plater knows this formula. 😜
PS. Can't wait for the book to come out.
Well said young man. Both a race car, and race craft are of little benefit on the road.
Many a fool has mistaken their good race craft to mean they automatically have good road craft.
I suspect you Julian value both crafts, and appreciate their differences.
These are excellent points. Driving on the street and driving on a race track are vastly different environments. So naturally, the suspension setup will be different.
I see lots of young guys trying to mimic race car setups on their road cars, thinking it'll make their car better on the street. That's not necessarily true. I wish more people could understand this.
I love watching your videos. I plan on buying your books.
I have a Mk1 Focus I use at The Bend as well as touring targa events. It was hard to find a happy medium with it, but it actually works. Coilovers certainly helped. The hardest part was in keeping it road legal. In SA you can't even modify the pedals without mod inspections. The trick is to use parts from later models that look the same but fix shortcomings in the earlier cars. Your books snd videos have helped greatly. Also on my third version of an undertray that makes the thing virtually a flat floor car. Thanks Julian.
I've done quite a bit driving on the race track and I can afree with everything you've said.
There is a drastic difference between optimal track and street setup. Track setup suspension is way too stiff dor street. A very good street sport seat is inadequate for track and so on.
I've driven my track car in the road quite a bit as well. I don't mind the fibreglass seat, noise from solid suspension bushings and engine mounts. I can put up with lack of lack of insulation and A/C, but I struggle with traffic. Track car feels clumsy at normal speeds. It's irresponsible.
Nice video as always Julian. I would like to see a video about tyre width and height when it comes to road car performance.
I bought your car suspension and vehicle aerodynamics. Love them (I believe I've left 5 stars on both long time ago). Can't wait for your incoming suspension book. Thanks for your kindly sharing.
i think a lot of your concepts apply to motorcycle tuning as well. It'd be interesting to see your take on a street setup.
I have no experience of motorcycles so I won’t be covering them.
I run flat ride on my street prepared/tracked m3. Softer/lower frequency front rates to achieve flat ride vs rear springs, and to achieve neutral handling, I increased front roll bar. Car is not cushy on road, but feels great both on road and track. I'm not running aero, so softer springs actually help with grip and confidence. I feel like most people overspring their cars (or kits/coilovers they buy come with too high frequency front rates) and that feels sporty, but not necessarily faster. I'm a believer and practicioner of flat ride. Good vids, thanks for sharing.
A good, thoughtful comment!
What is flat ride?
@@goldar4846 - You can google it. There's plenty of info.
That said, my E46 track car is also setup for flat ride. IMO the rear springs are too stiff for road driving. That car does NOT like speed bumps! But it's great on the track.
@@goldar4846 A suspension tuning technique where the rear sprung and ride frequencies are higher than the front, which reduces pitching over some bump profiles at some speeds. Most roadcars use flat ride because it is comfortable at road speeds over typical bump profiles.
What tire setup do you run on flat-ride suspension? Square (same width and diameter front and rear) or can staggered work, too? Obv square is most applicable to a road car due to tire rotations, but staggered always has the "style" factor, and that matters to some. Plus you can also tune under/oversteer with a tire stagger, particularly on cars that have excellent or rearward static weight bias.
I wonder how flat ride would affect tire and roll bar selection on a FWD...
Fantastic as always mate
Thank you.
The priorities and requirements aren’t the same, but the physics are the same.
Dropping suspension tuning settings into two distinct categories is somewhat misleading, as it can heavily depend on their driving preference and skill. There are drivers out there who prefer their track car to ease into an understeer condition, as it's more predictable and easier to correct. And there are drivers who prefer their street cars to naturally enter a controlled oversteer, as it improves chances of recovering when accidentally entering a corner too hot. Softer suspension is more forgiving with input errors and offers more feedback with body motion , while stiffer suspension leaves less room for errors, and less feedback. I personally prefer my street car to be twitchy and oversteer prone, which I do find comfortable with daily driving, but it also makes me uncomfortable with having inexperienced people drive my car.
Well said...
I don’t know anything about suspension setups, but someday I’d love to have a second car that I can be entirely impractical with… CZcams actually recommended me something great for once!
Excellent video. Congratulations and thank you
I have Impreza sti spec c, it is jdm track focused car, it is lighter, better weight distribution, braces everywhere etc. But to make suspension stiff from factory, Japanese has lowered the car with shorter and stiffer springs, so it sits on bump stops basically all the time. And that is the only thing what they did to suspension. It makes ride super bumpy and I would say dangerous on high speeds 150kmh+ on uneven roads. What do you think about such solution?
All road cars need adequate suspension travel. I've had a Japanese car that from the factory impacted the bump stops a *lot*, and both ride and handling were much improved by fitting longer springs. It's a case study in the book.
That's why I always preferred the Evo Lancers. They rode much nicer. The 7 was my favourite.
been following your videos for bit now, always good information, thank you. got a bit of an unrelated question, what are your thoughts on brake master cylinder stoppers? worth spending money on?
If the firewall flexes. Probably good to ask if others with the same car have experienced an improved pedal feel after fitting one. If people can't feel a major change, I wouldn't bother (minor changes are probably just imagination!)
@@JulianEdgar noted. thank you, appreciate your reply
One distinction between road and track setups seem to be the importance of flat ride as the dampening ratio is higher. I wanted to model if flat ride matters. So, there an equation for “flat ride” dynamic pitch stability? I could not find a way to translate the digressive sin wave in the x-axis.
The book covers flat ride, including some very good references for those (like you) wanting to explore further.
@@JulianEdgar Oh, okay 👀
Between 90-120 mph (typical freeway speeds). I feel the lack of aero has an effect on the stability of my car. Maybe im wrong maybe not. Should I look into it or focus on track width, stiffer suspension, lower cog?
If stability gets worse as speed increases, it's very likely to be aero. My aero book has a specific chapter on improving stability - www.amazon.com/Vehicle-Aerodynamics-Modification-Development-alternative/dp/B0C87VYVL8
Julian only question I have is kinda off topic (maybe). On you honda insight you made a comment that if there was a redo you would not have done the front in air ride. Was that purely due to complexity and cost or were diminishing returns also part of that statement. I have a 65 corvair that I am considering doing on a similar setup and obviously won't have near the fabrication involved other than perhaps damping angles.
There weren't sufficient specs available on the MacPherson struts with rolling lobe air springs, so the design wasn't quite right - too stiff. And then the struts weren't designed to allowing sufficient softening by the use of external reservoirs - the air connections were too small. If you can use - say - Firestone rolling lobe air springs at all four corners, then you could get excellent results. Air springs are covered in my new book, and in detail in my existing book on air suspension.
Hey Mr. Edgar, what are your thoughts on Verus Engineering's Aero? I'm not an Aerospace engineer or automotive engineer and looked at their technical papers, but wanted to see what you thought about them
I've looked before. CFD is very hard to do effectively without an incredibly detailed CAD model, and I very much doubt the company has had each car scanned to achieve that. There are no on-road measurements as far as I can see - such measurement is far more accurate than CFD without a highly detailed, scanned model. The products are probably better than many, but could be much better again with some proper testing. (If in fact they have on-road or on-track aero testing, please direct me to it.)
Edit: I might add that at least some of their CFD modelling looks appalling - check the complete lack of undercar detail on the purported CFD modelling of the Supra diffuser - www.verus-engineering.com/web/content/31918?unique=c12e2b686fe77f0480c7735b8643ac9778509541&download=true That is 100 per cent guaranteed to be all wrong.
@@JulianEdgar CFD is particularly unusable for simulation purposes, where as you said, it can be all wrong entirely and by a very large margin. At best it will just be all wrong for the most part. It is more of a tool for assisting with deciding the best design changes when compared to a prior product, not for measuring abs outputs.
"Aero engineers" who work with CFD have argued this with me for over a decade.
A bad wind tunnel will be just as bad as CFD, though. If the road doesn't move, it's pointless.
@@JulianEdgar thank you for the insight! Will definitely get "the book" and design it myself
"I´ve set up my car like a formula 1, and now it doesnt want to go off road!!!"
well, duh...
Is this book $1000 dollars?
No, I wouldn't expect so. Probably similar to the cost of my current major book on aero - Amazon is currently listing that at US$92, but they do vary the price a bit.
I independently observed all this while developing my car over the years doing autox and daily driving the car. This is not proof Julian understands whats going on, however confirmation I am doing and experiencing things mostly right.