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      10-13-2021, 05:25 PM   #9
Ascanio
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Drives: Mazda MX-5, BMW Z4 M Roadster
Join Date: Dec 2013
Location: Savannah, GA

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Quote:
Originally Posted by bwright657 View Post
I am an automotive engineer and can tell you that suspension and tire tuning is probably one of the most difficult parts of developing a car. Compromise is the key word here. Every change affects ride, noise, handling, cost and more. The best thing I can recommend is to first do driver mods. Any kind of driver training will do much more for you than mods on the car. The fastest driver will be the one who can use the full capability of their car, not the guy who has $10k in mods but can't push the car beyond 8/10.

If you do want to change up your car, first understand what you want the car to do, then do as much research as possible. If you want something track-focused, you're going to lose street comfort. If you want street comfort, your car won't be as good on the track. And when it comes to suspension and tires, you will absolutely get what you pay for. The reason Ohlins and high end Bilsteins are so expensive is because they do OEM level R&D and need to get returns on those costs.

If you want to move away from stock, start with the wheels and tires first. The spring/shock setup you need for a 200TW track focused tire will be completely different than the setup for a 300TW PS4S or an all-season tire. Slicks will be in a completely different world. When you're doing suspension, any old rubber bushings should be replaced as well. Worn out bushings can make the car crashy over bad pavement and can negate any benefits from new springs/shocks. Any car that sees street driving should have rubber bushings. I would only go poly or solid mounts if the car is dedicated for track use.

Then after suspension and a good alignment, you can use alignment settings or sway bars to fine tune your setup. The key is to only change one thing at a time so you can learn your car. Getting help from an expert really helps here too. I spent half a track day fighting terminal oversteer in my Miata. I was adjusting my shocks but could not get the rear to hook up in corners. A buddy of mine who is a test driver for Michelin took the car out and after two laps diagnosed the issue as not enough tire pressure in the rear. The sidewall was folding over on the tire. We added 2psi in the rears and the car would not let go.
Dude, for someone who has spent a lot of time with test drivers developing the suspension design for the Alfa Romeo Giulia QV, it never occurred to me to bring my Miata to them to fix the happy rear: I had to dial the front back to balance things!!
Will try playing with pressure!
Got a 2.5L MK3 with 235s on TE37s and Ohlins which feels more competent than my stock Z4M but is unbearable to drive in town.

Thanks!!!
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