Aftermarket Coil-over Rebound Setting Preferences

[Solid Red 98]

I have recently installed some BC Racing coil-overs that I got a screaming deal on. Now that my GTS is nicely lowered, and I can easily control ride height, spring preload, and rebound adjustments, I would like some input on suspension balancing in terms of rebound dampening front to rear. On the GTS, in particular, how does front vs. rear rebound affect the handling traits of our cars in terms of rear end traction over/under steer/snap etc.?

Here are my current alignment specs with .5" of front rake.

Front L/R

camber: -0.1
caster: 6.3
toe: 0.04

Rear L/R

camber: -2.0
toe: 0.09

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[Dom426h]

I have some good info on how to set up shocks that applies to any vehicle. I'll track it down and post in a bit.
Basically you start by setting bump(compression) & rebound on the shock both to 0. Then you increase the compression setting until optimized. Next you adjust the rebound until optimized.

What are your spring rates front & rear?

On your alignment. Was that by choice?(like you picked those specs?) or is that just what it was when you checked and you are looking for advice on that as well?
I think that you have too much camber in the rear, and too little camber(basically none) in the front. That setup would leave you plowing(understeering) in the turns when pushing her hard.
Around 1.5-2.0 in the front
and around 1.0-1.5 in the rear is what i recommend for performance oriented driving.

 

[Dom426h]

http://www.bimmerhaus.com/tech/shocktuningTN.html

http://www.ozebiz.com.au/racetech/theory/shocktune.html

http://www.wtrscca.org/tech.html

I recommend reading through all of these several times(until you fully understand them) before adjusting shocks.
The more you learn about shock tuning the more you realize just how important it is in keeping your car planted while going through a turn at/near the limit.

 

[Solid Red 98]

I have some good info on how to set up shocks that applies to any vehicle. I'll track it down and post in a bit.
Basically you start by setting bump(compression) & rebound on the shock both to 0. Then you increase the compression setting until optimized. Next you adjust the rebound until optimized.

What are your spring rates front & rear?

On your alignment. Was that by choice?(like you picked those specs?) or is that just what it was when you checked and you are looking for advice on that as well?
I think that you have too much camber in the rear, and too little camber(basically none) in the front. That setup would leave you plowing(understeering) in the turns when pushing her hard.
Around 1.5-2.0 in the front
and around 1.0-1.5 in the rear is what i recommend for performance oriented driving.

These alignment specs are a custom street align. The rear is running a bit more negative camber to avoid rubbing issues due to the 345 19 Michelins .(they just barely clear ;-} ) I felt like more negative camber in the front would be better as well, I get a few free adjustments on that. I have read up on general shock settings, so I have accumulated some knowledge of the basics. What I was looking for, even though damping behavior varies among shock manufacturers, is some Viper GTS specific impressions with respect to front/rear damping relationships since our cars have some handling personality quirks. Over the years I have learned the limits of the stock suspension, but now its a new car and I am the test pilot without a good proving ground to safely tune it until the weather warms and dries. So far, the car feels transformed and is so much more planted, inspiring a new confidence that I don't wish to overplay. I will likely use SCCA meets for some tuning, but the season has to get going first. Thanks for the links, I will peruse them as well.

 

[Jack B]

are both rebound and compression adjustable