I recently mounted up my 2nd-hand KW variant 3's and found I was getting some clacking from the rears over low speed (15-35 mph) washboard streets. I thought something might be loose so I re-torqued everything to spec, checked the sway bar links and all was good, but still the clacking. So I pulled the rears, disassembled the springs, bushings and hats and reassembled everything. I even replaced the top mount bushings that had been drilled for my Koni's just in case the little gap was an issue. Reinstalled, re-torqued and still the clacking which was again only noticeable at low speeds. So, I pulled them again and sent them to KW for testing and they put them on the shock dyno, checked all the valving and they're in fine operating condition..ie. to spec.

So in they go again and clackety-clack-clack. I have since run them at the MSR DE event, and they felt great. They dampen just fine, but they make some noise when I get on a concrete street. Is it possible the helper springs are the source of noise on certain type of pavement joints etc.? Really not a problem when the car is moving at speed, just at lower speeds when the body is getting tossed around on washboard pavement.

Mystery...

 

On some coilover systems, the top hat which is metal will make noise against your chassis. It is perfectly normal for the most part... mine does the same in cold weather sometimes.

 

Enough preloading on the springs?

 

On my Prelude, my Tein HAs made the same sound. I bought David's RAs for the S2000, and he said he had heard the same sound with them, but I haven't noticed it since installing them on my car.

I can't tell you what the difference is, though. Maybe just verify that the upper mount is seated firmly agaist the 'chassis' or whatever you want to call it. That's the only part that I can think of that would clack. I still get a solid "whump" when I go over some bumps, just because the upper mount is a "solid" type and it transfers the impact more directly, as opposed to the rubber ones with the stock shocks. But I don't get the almost-rattle "clack" sound that I got in my Prelude.

 

The KW's use the stock upper bushing mount (or "hat") so it's not like it isn't designed for the S. I'll post a photo, but I think the coilover looks like most others...starting at the top there's the stock bushing mount, upper spring support aluminum ring (which mates the spring to the stock rubber upper bushing, then the main spring, then a plastic spacer ring, the helper spring and the adjustable bottom spring mount. Something in that stack is the culprit and it's certainly not loose where the hat bolts into the car body or at the bottom mounting point.

 

I get that noise and I have the stock setup. Seems commom around the forum.