What would need clarified is "increase rebound dampening".

Normally, Increasing rebound +, decreases the speed/force exerted downward.

they might actually mean to lower you rebound setting to increase that force.

weight transferring at a slower rate from front to rear isn't going to make a big difference on front grip on corner exit but likely works with transitional traction IMO.

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Steve, I assume you're talking about the Sachs shock tuning guide on my website, can you give me some specifics?

 

just taking a quick read through the fine points of penske's tech manual here makes me want 3 ways after I'm tired of these clubsports
http://www.penskeshocks.co.uk/downlo...TechManual.pdf

 

yes, thanks. Make no mistake, I have little understanding in shock tuning, but have read a few books on general suspension design...enough to be familiar with verbage, but not enough to offer useful advice--hence my confusion. If the steady-state of the car in a turn has no dynamic input from shocks, how does adjusting them help with mid-corner understeer, for example? If it does help, the Sachs reference suggests softening/decreasing the front (rebound and compression) and stiffening the rear. The Staniforth/Simmons flowchart says nothing about rear adjustment, but suggests stiffening front rebound, and adjusting front compression based on whether there is too much roll (subjective, of course), among other things. Those two recommendations seem to me to be in conflict. Again with oversteer recommendations: Sachs guide says stiffen the front, soften the rear while Staniforth/Simmons says increase/stiffen rear rebound, decrease/soften rear compression (among other things) and makes no mention about adjusting the front. Third, the Sach's guide says to soften front rebound with corner exit understeer, while Staniforth says to increase/stiffen front rebound.


I recognize that shock adjustment isn't something that happens in a vacuum isolated from other aspects of setup. But at an event if the surface is more or less grippy than expected one typically has only tire pressures and shock adjustments as variables while sitting in grid.

I appreciate your opinion, and apologize that this may have gotten a bit offtopic!

 

My track settings for BW:

Compression F: 2 from full stiff
Rebound F: 2 from full Stiff

Compression R: 2 from full stiff
Rebound R: 4 from full stiff

At SOW: Raise F Rebound to 1 from full stiff.

Notes: Nonstaggered w/255x4, non-aero.

 

Antonov, thanks for sharing your setup, what spring rates, anti-roll bars and camber settings are you running?

 

My guess is the Sachs guide assumes there are no real-world granite tabletop smooth corners so shock adjustment will affect the handling in the corner. Also, the Sachs guide is specifically for the Ford Mustang race car which doesn't handle all that great so their power application in the corner will probably come later than a typical race car. Throttle application in the corner has a huge effect on handling and the required suspension adjustments, especially with big V8 torque on tap so maybe the Sachs guide isn't the best tuning guide for the S2000.



I don't see how stiffening front rebound would help with mid corner understeer.



The Sachs guide makes sense to my non-suspension engineer brain here.



The Staniforth graph makes more sense here. Normally adjusting rebound at the opposite end of the car is done to change the rate of weight transfer. Adjusting the compression and rebound on the same axle is done to affect traction. I believe this probably accounts for some of the discrepancies between the two shock tuning guides. I did some searching and found Allen Staniforth's understeer and oversteer guides from his book and I'll put them up on the web page.

 

I read that as you get NEW mid-corner understeer (entry was fine, then understeer develops mid corner). So your compression is good at turn in but then at mid corner your front is lightening up due to lack of rebound stiffness. Increase the front rebound stiffness to keep from developing that understeer by keeping the front planted longer (or slow the weight transition off the front)

 

We're actually pretty close. I'll try your settings next time but I think it might be too stiff for me.

For BW: I use:
2 off full stiff compression
4 off full stiff rebound

2 off full stiff rear compression
7 off full stiff rear rebound

Sway bars: Eibach front, OEM 05 rear. Spring rates are standard KW CS springs. I believe 571lbs all around, on street tire.

 

Thanks for adding those charts, Rob. The MCoupe one I linked is a direct copy of that--the companion MCoupe oversteer alogrithm has an error in it, so if anyone sees that floating around please take note and follow the Staniforth ones posted here...Interesting point about the Sachs being more Mustang-specific given its different suspension setup, power differences etc.

Clark, thanks for that clarification. That is what I experienced in my car (along with some exit understeer) and confirmed that increasing front rebound stiffness helped that go away--hence my confusion with the Sach's recommendation. Clearly, autocross turns are sharper, shorter in both length and duration to roadrace/track turns, so there's probably some nuance that gets lost in translation as both of those charts are for track use.

I should also edit my comment about the Staniforth guide not mentioning front adjustments to handle exit oversteer. I assume that the comment "Improve traction weight transfer by increasing the amount the rear 'squats' under power" in the flowchart to mean that one can stiffen front bar, soften front rebound in an effort to promote better/faster rearward weight transfer to keep the rear tires in contact. That seems to flow well with your concept, Rob, about adjusting the opposite "axle" to affect rate of weight transfer.