B8 S4/S5 Suspension Thread

If u like it then it’s OK. Obviously it works for u :). But that much toe in delays turn in response and makes the car more pushy on entry. It also reduces how darty the car responds to changes in steering angle, and causes mid corner understeer to happen sooner.

Think of it this way…when your two front wheels are turned, the inner wheel travels a shorter distance than the outer wheel. By toeing in, the 2 tires fight each other and the disparity in distance traveled when the wheels are turned is greater. This puts more heat in your tires, more tire wear and a poorer handling car. Toe out is the opposite, and causes the inner tire to point more sharply towards the corner…so that it accounts for the smaller distance travelled by the inner tire better. Any track or race setup will have toe out on the front tires. at worst, it will be 0 toe. But never toe in on the front unless the car handles very funny and requires a reduction in front end grip and response…which IMO is the opposite of what an Audi needs

Love this guide. I bolded my choices.

http://www.thesmokingtire.com/2012/massive-list-of-solutions-to-understeeroversteer/

[quote]Understeer Corrections
Drive a different line.
Use weight transfer to your advantage.
Push, plowing, front tires slide out first.
Usually slight under-steer is safer.

Raise front tire pressure.
Lower rear tire pressure.
Soften front shocks.
Stiffen rear shocks.
Lower front end.
Raise rear end.
Widen front track.

Install shorter front tires.
Install taller rear tires.
Install wider front tires.
Install narrower rear tires.
Soften front sway bar.
Stiffen rear sway bar.
More front toe out.
Reduce rear toe in slightly.
Increase front negative camber.

Increase positive caster.
Soften front springs.
Stiffen rear springs.

May need more front suspension travel.
Install wider front wheels.
Use softer front compound if possible.
Use harder rear compound if possible.
Remove weight from front of vehicle.
Add weight to rear of vehicle.
High Speed. Increase front wing down-force.
Too much front brake.
Vehicle is TWITCHY at limit and hard to keep ahead of in the steering department.
Lower front and rear tire pressures slightly.
Suspension may be too stiff.
Shocks may be set too firm.
Tires may be old or hard.
Vehicle may not have enough suspension travel.
Vehicle may have a toe problem front or rear.
Increase negative camber front and rear if possible.

Oversteer Corrections
*Driver may be going in too deep.
*Driver may be getting on the throttle to early.

Loose, rear tires slide out first.
Oversteer can be dangerous, especially at high speeds.
Lower front tire pressure.
Raise rear tire pressure.
Stiffen front shocks.
Soften rear shocks.
Raise front end.
Lower rear end.
Reduce rear track.
Install taller front tires.
Install shorter rear tires.
Install narrower front tires.
Install wider rear tires.
Stiffen front sway bar.
Soften rear sway bar.
More front toe in.
Increase rear toe in.
Reduce front negative camber.
Reduce positive caster.
Stiffen front springs.
Soften rear springs.
May need more rear suspension travel.
Install wider rear wheels.
Use harder front compound if possible.
Use softer rear compound if possible.
Add weight to front of vehicle.
Remove weight from rear of vehicle.
High Speed. Increase rear wing down-force.
Too much rear brake.
Vehicle slides and is easy to drive at limit but
does not corner to full potential.
Raise front and rear tire pressures slightly.
Suspension may be too soft.
Shocks may be too soft.
Roll centers may be too high.
Lower vehicle.
Tires may be too hard.
Widen track front & rear.”
[/quote]

Those lists are so bad. Those setup tips are only valid for specific parts of the corner under specific driving conditions (steady state vs on power vs off power vs on brake vs coasting etc).

It’s a good baseline for experimentation, but do not refer to it as a tuning Bible by any means. They can be very misleading

It’s more thought provoking than anything. It makes you consider the equivalency of various tuning parameters. Of course the efficacy of any given adjustment will vary by platform. That is the tricky part.

-3.2 was too much camber. -2.5 is the spot.

https://uploads.tapatalk-cdn.com/20170711/fd288e8566f5f7669c72dce8d00232b5.jpg

I’m changing the rear spring from a 650 lb to an 800 lb. It’s about 23% stiffer. The person who built the kit for me gave me an option of a 750 rear spring when I ordered. With the wing, I think I need 800. Despite the car being 0.75" higher in the rear, it sinks at least an inch at high speed.

Got some used springs from a racecar. Fun fact about steel springs - they don’t wear out.

https://uploads.tapatalk-cdn.com/20170920/db5a51e73dea2a0a3608887cd4a39cb8.jpg

what race car?

No clue. Probably a Porsche or Aston Martin, as that shop specializes in those.

I’m probably past the point where I should have switched to slicks for the track. Might go with Hoosier R7 (265) on BBS CH-R (19") in the future. Have to find a good portable jack, some wheel studs, etc.

The 800 pound rear spring, plus the wing, and 500 pound front spring is a great combination. The car is really sure footed. A crazy amount of mechanical grip, actually. The weakest part of the car now is tires. Thinking of trying the RE-71A. I know they’ll only last 6 track days.

Great to hear. What spring rate is the stock spring.

Like 200 progressive.

Also, I’m going to toe out the front wheels to -1/16 total. Somehow I lost that setting. And pair it up with RE-71R tires this time, just to try something different. I think they are 3-4 pounds heavier per tire, about $100 cheaper, and allegedly have 2/3 the track life. I usually run the Michelin Cup2.

WOW that’s a big difference in spring rate.

It’s sprung very soft for rear seat passenger comfort. I think the aftermarket street kits are like 300 progressive.

https://uploads.tapatalk-cdn.com/20171118/a324ad0c6b7fba978ee4c8450f7a2875.jpg

034 rear toe links.

https://uploads.tapatalk-cdn.com/20180201/f01e897e0008486204163e36e6b0a6ef.jpg

Are you getting even tread ware on the car with it set up that way

West, do you know what spring rate your helper/tender springs are?

I started out running 7" springs with no helpers on my m3, then added the Swift 168 lbs/inch helpers up front and went to 6" springs. I’ve just removed the helpers and the car feels more connected without them, you might give this a try. Most folks running helpers are running near 0 rates, but I wanted to try something different thinking it might increase street comfort, wasn’t really worth it. If you are closer to 0 rate you may not feel any difference.

I believe this is the toe link I’m replacing. I just figure the bushings are shot. I tried to order this part with spherical bearings but they don’t sell it and couldn’t custom build it for me. I asked a few times.

I think the front tender spring is like 100 and the main spring 500. I don’t think there is a rear tender spring, just an 800 main spring.

https://uploads.tapatalk-cdn.com/20180201/95ffd7048f14ed365e41c9652b176d5e.jpg