Im finally done with all the mods to my LS7 engine and have it tuned the way I like. The throttle response and low speed torque has really increased. So im moving to the back of the car to try and get some more plant the rear tires performance. I run the rear sway bar on the stiffest setting and currently have a 275lb springs on jri double adjustable shocks. As I accelerate out of a sweeping turn the back gets loose and skips out. The shocks are set up to dse recommendations. The rebound adjustment is 20 sweeps from full dampening, I don't know a lot about suspension tuning and was wondering is full dampening the stiffest setting? Also wondering if the springs are to stiff and how the bar plays in to the spring rate. Any suggestions on how to get it, to become more complient and grip a little better is appreciated.
Okie dokie, first step would be to start with baseline shock settings in the middle, go test with "just" shock adjustments & take very detailed notes every change, every "run".
You didn't say if your double adjustable shocks are compression & rebound adjustable or if both adjustments are for rebound (low speed & hi-speed piston travel).
If they are compression & rebound adjustable, do this:
a. Soften the compression on the fronts until you get the car "loose on entry" when braking & turning ... or until you run out of adjustment.
b. Stiffen the rebound on the fronts .. and see how much better the car turns "mid-corner" when you're "rolling or coasting" with no brakes or throttle. Also pay attention to what it does to the rear tire grip on corner exit. It will get looser. Note the settings when it does.
c. Stiffen the compression on the rears as long as it helps the car turn on entry & middle ... or until you run out of adjustment.
d. Soften the rebound on the rears until you get the car "loose on entry" when braking & turning ... or until you run out of adjustment.
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Then ...
e. Stiffen the rebound on the rears to see if will provide you with more grip on corner exit. Pay attention to when it affects grip on entry & middle.
f. Soften the compression on the rears to see if will provide you with more grip on corner exit. Pay attention to when it makes the car tighter or pushy on entry & middle.
g. Stiffen the compression on the fronts until you get the car to push on entry and/or middle ... or until you run out of adjustment. You'll be able to drive in deeper & brake harder, but pay attention to the middle as it gets tighter or pushy.
h. Soften the rebound on the fronts .. and see how much better the car grips on corner exit as you roll the throttle on. Also pay attention to when the push comes back or gets worse in the middle. If it starts to push on exit ... stop.
Please do these in this order & take lots of notes. You won't be able to remember all the details accurately. I don't know any top race teams that don't use "run sheets" to keep track of changes, results, etc.
Then, post a report of each run, with all 4 shock settings, the handling results on corner entry (braking & turning), Middle (coast) & Exit (throttle roll on & steering unwind) ... and the differences from the previous run.
You'll learn first hand what changes do ... I'll guide you on what every thing means to us from what you post ... and people following along can learn & share their experiences too.
Ok … since both adjustments are for rebound (low speed & hi-speed piston travel) do this:
a. Soften the high speed rebound on the rears until you get the car "loose on entry" when braking & turning ... or until you run out of adjustment. This will help the car turn better on entry & middle.
Note the settings when it does get loose & back up a step.
b. Stiffen the low speed rebound on the fronts … and see how much better the car turns "mid-corner" when you're "rolling or coasting" with no brakes or throttle.
Pay attention to what it does to the rear tire grip on corner exit. It should get less traction. Note the settings when it does.
c. Stiffen the low speed rebound on the rears until you get the car "loose on entry" when braking hard & turning ... or until you run out of adjustment. Note the settings when it does get loose & back up a step.
Pay attention to what it does to the rear tire grip on corner exit. It will get more traction. Note the settings when it does.
It “may or may not” tighten up the car mid corner. If it does, note the setting & back up some.
d. Stiffen the high speed rebound on the fronts … and see how much better the car turns "mid-corner" when you're "rolling or coasting" with no brakes or throttle.
Pay attention to what it does to the rear tire grip on corner exit. It should get less traction. Note the settings when it does.
---------------------------
Then ...
e. Stiffen the high speed rebound on the rears until you get the car "tight on entry" when braking & turning ... or until you run out of adjustment. This may make the car harder to turn on entry & middle … potentially creating a tight/pushing condition.
Note the settings when it does get too tight or pushing & back up a step.
f. Soften the low speed rebound on the fronts … and see how this makes the car harder to turn "mid-corner" when you're "rolling or coasting" with no brakes or throttle.
Pay attention to what it does to the rear tire grip on corner exit. It should get more traction. Note the settings when it does.
g. Soften the low speed rebound on the rears to see how it affects the car on entry when braking hard & turning ... this may tighten or loosen the car on entry & may not, depending on other factors Note the settings if it does change.
Pay attention to what it does to the rear tire grip on corner exit. It will have less traction. Note the settings when it does.
It “may or may ” loosen up the car mid corner. If it does, note the setting & back up some.
h. Soften the high speed rebound on the fronts … and see how this makes the car harder to turn "mid-corner" when you're "rolling or coasting".
Pay attention to what it does to the rear tire grip on corner exit. It should get more traction. Note the settings when it does.
Please do these in this order & take lots of notes. You won't be able to remember all the details accurately. I don't know any top race teams that don't use "run sheets" to keep track of changes, results, etc.
Then, post a report of each run, with all 4 shock settings, the handling results on corner entry (braking & turning), Middle (coast) & Exit (throttle roll on & steering unwind) ... and the differences from the previous run.
You'll learn first hand what changes do ... I'll guide you on what every thing means to us from what you post ... and people following along can learn & share their experiences too.
Agreed. Ron, when I get my Penske's I'm dragging you out to the track with me.
Let's dial in the valving curves first. We need to adjust the bleeds & shim stacks to get the low speed rebound numbers where we want them for grip ... without the high speed numbers being so stiff it upsets the car over rough surfaces.
Brian Hobaugh SCCA National Tour June 2014
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