I have S/As now on my M Coupe with 600# rear springs, but am somewhat unsatisfied with rear end behavior going over undulations/bumps mid-corner. I also have Ireland rear subframe bushings.

If I dial up lots (nearly all) the damping, I get choppy, buckboard ride. Softer results in rear dancing a bit as it absorbs bumps in the corner (Michigan roads--bumpy corners are the reality). Is this simply the toe changes and resultant steering I am feeling?

I use this car 99% road only and it has plenty of grip--just want to know if D/As will provide some fine tuning I can't get to with S/As.

Thanks.

Call me crazy, but 600# springs on a car that sees 99% road jumps out as the first problem to me... You're not going to get good handling over bumpy roads with spring rates at the low end of/approaching real track rates.

Can you tell if it's a bump or a rebound problem?

Call me crazy, but 600# springs on a car that sees 99% road jumps out as the first problem to me... You're not going to get good handling over bumpy roads with spring rates at the low end of/approaching real track rates.

+1 99% deserves road rate springs. I am running much softer rear springs on a dedicated race car.

+ 2 on rates.......

I run a 99 z.8 coupe w/ a mild Dinan set up........no big issues,.... even at track.....

Can you tell if it's a bump or a rebound problem?

...I always thought bump= rebound.

So, bump = compression? It does seem to make sense now that I type it.....

bump = compression or 'jounce' in the Queen's English.

Stiffer suspensions react faster, but you can compromise grip if you aren't careful with your spring/damper combinations. Even though the semi-trailing arm requires a stiff spring compared to its wheel rate, you shouldn't go too stiff. The short wheelbase and stiff M Coupe chassis combine to make the car more of a handful than your typical E36.

bump = compression or 'jounce' in the Queen's English.

Stiffer suspensions react faster, but you can compromise grip if you aren't careful with your spring/damper combinations. Even though the semi-trailing arm requires a stiff spring compared to its wheel rate, you shouldn't go too stiff. The short wheelbase and stiff M Coupe chassis combine to make the car more of a handful than your typical E36.

Regarding your shocks, yes - you'll see *much* better ride quality from the TCK DAs set full soft on compression with the appropriate rebound rates for your springs. I had to use SAs for a couple months while I waited for DA availability, and they were really struggling in autox use to control 600 lb springs. The DAs are much better suited.

But I'm jumping in with everyone else on this: you have no need for 600lb springs if the car is 99% street use. Get a set of 400s and you'll have a significantly more enjoyable driving experience without any meaningful drop in performance. If you're going to the track, swap in the 600s.

Oh, and if you use TCK VVS springs for this, you won't have to adjust ride-height. They're already variable lengths to approximately put you at the same ride height.

Mike

I'm using TCK D/A s on my 98 M Roadster, which is heavily tracked (107 days and counting) but somewhat used on the street. I have 450f and 500r springs. My trusted authority on suspension setup recommended 3 clicks of bump for the street. Even at that, bumps in the street under cornering are very problematic. Remember, this suspension setup is designed for the track. Public roads are not designed for high performance driving.

I used to own an Mcoupe and ran 650lb springs in the back. Since its basically the same rear end as the e30 m3 you don't want a lot of movement for track use. I had DA Konis on the back and I remember when I first installed I had the same issue you described. I played around with the settings and got it to behave pretty nicely on the street. Its been 4 years since I owned it so I don't remember setting specifics. I was able to get it to behave pretty well on the street though. She was stiff but Wow what a transformation with the suspension!

I reckin' I chose the 600's as the real wheel rate with the trailing link rear suspension is still somewhat behind the front end's 400# rate (I believe it would take a 660# rate to match real front rate)--and I feel the rear using more travel on a given bump--or at least that is the impression sitting with rearward bias the Coupe has.

I don't mind the bump ride quality going straight ahead over bumps. The corners almost feel like a mini-hula dance--side-to-side--as the suspension is using a lot of travel on some of these corners/exit ramps. The Irelands should be working on that....Maybe I am feeling rear-steering?

I had 500's and sold them and felt the car was matched better with the 600's. But, what do I know.....I'll keep playing with damping and just do the logical thing: Call TCK. Thanks for the input so far.

I am a BONEHEAD: I assumed, using an unmarked adjusting wrench, that I was near full-hard--I was near full-soft. In other words--I was turning the adjustment exactly the wrong way.

I will go now.....and see if she dances a little less! Sorry all.....

Well, that explains a lot. :) tell us what happens!

I am a BONEHEAD: I assumed, using an unmarked adjusting wrench, that I was near full-hard--I was near full-soft. In other words--I was turning the adjustment exactly the wrong way.

I will go now.....and see if she dances a little less! Sorry all.....

"She canna go harder Capt'n!!!"


When in doubt, blame the operator. :stickoutt:D