I'm having a difficult time getting dialed in. I'm running 650F/550R springs, Gendron front hollow bar on second stiffest setting, and oem rear still attached. Shine hardtop and APR GTC-200 wing at 0*. Alignment is -3.3*F/-2.7*R camber, 6.6* caster, and 0"F/.125"R total toe. Tires are RA-1's: 235/40/17F & 255/40/17R on CE28N's(staggered). Car weighs 2600lbs and has been corner-balanced.

I started by zeroing compression and rebound. Worked on compression first, and rebound. Front end feels a little "floaty" in high speed esses, however, understeer is not a problem at lower speeds. In fact, the car seems somewhat neutral compared to last year's understeer issues(less camber/less caster; OTS Koni's; 500F/550R).

Any suggestions or requests for more info welcome. It's been a frustrating year so far. All-in-all, the car just doesn't feel "right." I understand driving style can be a big factor, but I am comparing experiences from last year to this year's on the same tracks.

 

Skip - what are your current compression and rebound settings for front and back?

 

You cannot compare my setup to your KW's unfortunately.

 

Id start with
bottom settings stiff and the same all around
top settings stiff, but stiffer in the front than the rear.

and use that as your base

 

My $.02... This isn't perfect, but it'll get you in the ballpark parking lot. And it'll teach you what both bump and rebound do and feel like individually, which is very useful.

Set rebound to something pretty low, like 1 or 2 clicks from zero. Start with bump at about the same, go out for 2 laps, come in, go up 2 clicks, go out for 2 laps, come in and go up 2 clicks, etc. Repeat until the ride over bumps gets too "choppy" or skatey, and then go back a click or two. Pay special attention to how the particular vehicle corners (LF, RF, LR, RR) feel over bumps, and how the outside of the car feels during corner entry.

With bump set as above, do the same thing with rebound; go up 2 clicks every 2 laps or so. Pretty soon you'll notice that rebound has a pronounced effect on the car's balance & behavior during corner entry; and it should be easy to tell when you've gone too far. This point should be close enough to something you can use as a baseline setup for that track. When you get to this point, start to try overall front-to-rear differences to tune the balance of the car.

 

That's exactly how I started. Someone had previously linked an article by a guy on a BMW forum/site. Also, that's how either KONI or TrueChoice suggests on their site(s).

Thank you for taking the time to key all that in. When preloading the springs, I jacked LCA up until it brought the car slightly off the jackstands. I did this for all four corners. Could this be a possible problem- too much pre-load?

 

Yea, that's the common way to get ballpark with simple dampers. To start tuning them for balance, try keeping the bump/rebound ratios constant and go stiffer or softer on one end of the car. And/or, experiment with rebound; this will affect corner entry behavior noticeably.

Preload - Not quite sure what you mean by preload... If you "preloaded" it and then put the car on the ground and the springs compressed, all you did was limit droop travel or raise ride height; you didn't "preload" it. If this is the case, then yes that will cause undesireable things to happen on track. Anyway I'm not quite sure what you're talking about, and there are lots of misconceptions about 'preload' floating around the interenet, so give me some clarification on what you mean by 'preload'...? A picture of your suspension might help.

 

True, but stating the settings you've tried and the resulting bahaviors might help others to chime in and give input.