While driving with some friends that have different cars (a C6 Vette and a Porsche 911), I noticed that mine bounces over bumps, while theirs did a better job of absorbing them. I'm running the following:

Front: 350lb springs / Bilstein struts

Rear: 175lb springs / Bilstein shocks (not coilovers)

This setup seems to work well for track days, but not so well on the frost-heaved back roads of Michigan. Does anybody have a combination they use for track and street that works well with uneven pavement?

 

I've heard that the illuminas work well for both track and street, but they are getting harder to find lately.

 

Bilstein HD shocks, assuming this is the flavor you have, are stiff. Illuminas are great and adjustable.

Compromise setup is always a compromise. Go softer on front and rear springs and keep the ratio of front to back the same. Re-shock as needed

I used Eibach Pro Kit springs, the progressive fronts really helped with the bumps on the street. Not so great on the track. Ideally you'd have separate setups but thats a lot of wrenching every time you go to/from the track.

 

I don't think my Bilsteins are the HD version. They're the standard OE replacement shocks that were available back in the late 80's. I was told they provided very good ride quality. I used them with a Suspension Techniques spring set originally, then I had them re-valved when I went to the higher rate 350 / 175 springs.

A better description is probably that the car "skips" over big pavement imperfections. I don't have undamped suspension movement. Maybe I just need to back off on the spring rates.

 

there are two valves in a shock/damper/strut. the valves are in the speed the shock shaft has to move.

there is a high speed valve and a low speed valve.

the low speed valve is the handling valve, all the cornering inputs, body roll, and car control stuff happens at a low shaft speed. usually under 3"/sec.

the high speed valve is for bumps, as bumps are sudden, and the shock shaft speeds are higher than 3"/sec.

so if you're driving down the street and it rides badly, its the high speed dampening that is not right. if its a handling problem its the low speed.

99% of the shocks in the world aren't separately adjustable, so we usually just get the handling right, and live with the bad ride, but when you do get both correct its pretty magical as suddenly the car handles great, and rides really nice too

you should do a little looking into it, but i believe bilsteins can be revalved
Autocross to Win (DGs Autocross Secrets) - Shocks

 

Thanks -- very helpful. I'll see what Bilstein says about this type of revalving.

 

elwood, I think you'll continue to have problems on the street as long as you are running those spring rates.

I don't know what the rest of your suspension consists of, but I run 225 front/150 rear and it is a pretty rough ride on the road. Illuminas on the front help a bit, but the Bilsteins on the rear really let you feel it.

Sounds like you really want a high quality adjustable shock. But that is a very high dollar option.




.

 

im thinking the shock cant control the springs? some custom koni shocks might work well

 

Yes, what I really want is 3-way adjustable shocks so I can soften up the high speed compression or "bump" damping independent of the low speed adjustment. What I can probably afford is a revalve job on my current Bilsteins. We'll see . . .

 

i'm under the impression that every bilstein can come apart, and my friend has/had the shim -> shock force decoder book, so there is a learning curve (we don't know what shock force you have, or what you need, or have a way to really measure it), but other than that its doable.

the military measures ride height in WATTS. they measure the movement of the drivers head, and somehow get it to generate power