Hey guys earlier this year I picked up some KW V3's for the evo. I ran most of
the year with the settings KW recommends but I wanted to start dialing them
in more next year. Does anyone know of any good books or websites or past
threads on when to adjust compression and when to adjust rebound and
how the change handling characteristics? I tried searching on here and the
internet but didn't find anything concrete. Most of the stuff related to motorcycle
suspension. Any insite would be greatly appreciated.

 

If you feel like you've gotten comfortable enough with the car that you can accurately diagnose any handling issues that you're having, then double adjustables will provide great adjustability options. If not, then you could easily make things worse. What are you trying to change/fix?

 

Thanks for your reply...I have the standard front springs 8k and optional rear springs 7k. Even with the compression turned up I still exhibit alot of body roll and still feel like I'm understeering. The coilovers are not full stiff. Does rebound have any effect or should I just continue playing with the compression? I'm only lowered
a 1" to 1 1/4" the whole way around and my car was aligned and corner balanced. Any suggestions?

 

As a general rule, compression controls unsprung weight (wheels/tires/brakes/control arms) and rebound controls sprung weight (chassis, driver, fuel, etc). Rebound plays a larger role in controlling body movement such as pitch, roll squat and dive, so merely adjusting compression won't yield changes reductions in body roll.

Where doe the car understeer? Are you sure you're not just overdriving it? Do you know your braking points at whatever track you're evaluating the suspension on?

Compression and rebound CAN be used to fine-tune the car's behavior in corner entry and exit situations, but first you need to determine that the cause of the understeer is NOT the driver.

 

From experience, switching to stiffer rear springs has cured some of the understeer. As far as adjustments on a two way set up, the rule of thumb on the ratio of rebound to compression is 3-4:1. So assuming the valving adjustments are the same on rebound and compression on your coilover you want to stiffen 3-4 clicks of rebound for 1 click of compression. Since your problem seems to be body roll I would go 4 rebound for every compression increment. Be carefull not to go overbored as you could easily pass the capability of your springs and end-up with an overdamped car( too stiff dampening for the spring rate).

 

how does one feel shocks that are too stiff for the springs?

 

I'll go ahead and question why you feel it necessary to maintain any ratio at all between compression and rebound. In what situation outside of the need to preserve ride quality do you need to concern yourself with any relationship between rebound and compression? A big reason a manufacturer gives you a damper adjustable in rebound and compression independently is so that you can change each one without affecting the other. If there were some golden ratio to follow, all shocks would be single adjustable, with changes in rebound affecting a compression change of the same ratio for all adjustments.

Since the OP hasn't answered the key question at hand, I can go ahead and suggest a general tuning procedure, which is to turn the dampers to full soft on both rebound and compression, go out for some baseline runs and begin taking down numbers. Section times, exit speeds, tire temps, etc. Begin making adjustments in rear rebound ONLY in small repeatable increments, and record the same numbers after a few laps. When you feel the car begin to get loose, back off the last rear rebound an increment and work on the front rebound in the same manner. Then, do rear compression and front compression. Fine-tune from there.