mike9186

This Spring I swapped out my old wheels and tires (Boxster/996 wheels and Bridgestone tires) with Cup1 Replicas and Continental DW's. After driving for the Summer I notice that the rear suspension clunks a lot especially if I drive slowly over a break in the pavement. It almost feels like everything isn't quite tightened down on the rear suspension or the engine mounts have too much play (I swapped them out to 993 mounts a few years ago). Driving around everything feels fine however.

I know the Cup1's are heavier. Maybe the sidewalls in the Contis are stiffer? Should I get a realignment even though the old and new wheels are allegedly the same size?

Thanks!

Vandit

Alignment is not affected by a wheel/tire swap. I would not spend money on that.

Mr.Alex

If you have a clunk, I would recommend seeing that your motor mounts and strut mounts are ok.

From just swapping the wheels you might have more road noise/feel coming through the steering wheel (depending on tire), and some steering wheel vibration if your wheels are poorly balanced.

mike9186

I am going to check the motor mounts and the struts tomorrow. There is no steering vibration or road noise. The clunk is specific to going over uneven surfaces. For example, my driveway is gravel and when I drive into the garage over a 1" concrete lip, the rear engine make a very loud "CLUNK" and I can feel it vibrate through the engine and car....

alexjc4

Maybe anti roll bar/ sway bar drop links.

mike9186

I think you might be onto something Alex! I'm planning on replacing the rear bushings and spring plates this winter after I finish replacing the steering rack and front bushings, tie rods and drop links.

abarthguy

It shouldn't be the tires. The DW tires are much quieter than the Bridgestones I had before.

dsan

x2. The fact that you mentioned it happening only on uneven surfaces sounds like a torquing or flexing issue.

NoSub Dan

I bought a set of cup 1 replicas from a fellow Rennlister last week. I'm replacing D-90's and I plan to put conti DW's on the new wheels. The wheels arrive to me Thursday so my question is, should I do anything in to prepare my car for heavier wheels? Bushings? Motor mounts? I want to avoid problems but I can't wait for that stance! Thanks in advance. BTW it's a C2 cab narrow body.

mike9186

New Powerflex rear sway bar bushings installed and Tarett drop links. No more clunking!

I learned the hard way that the bushing brackets ARE directional and I had to flip one around after installing it because it was not fully closing the bushing around the sway bar. Note the ends: one is pointy and one is much flatter.

Here are some photos that show how the original driver-side rubber bushing was separating.

crg53

Out of curiosity, which way DO the bushing brackets go back, do they have the wide side to the front or the back.

mike9186

If you look at the second photo (left hand side of car, bushing just twisted so I could get a decent shot) you will see the pointier end goes toward the front of the car.