A couple months ago, I had the STI struts on my bugeye revalved by FEAL. Ever since, the passenger rear wheel has an incredibly annoying CLUNK, most easily replicated by driving over a slightly sunken manhole cover. Keep in mind, this is not the typical "STI strut clunk". I've dealt with that & know what it feels / sounds like. I just spent the whole day today disassembling that corner of the suspension, verifying torque specs, feeling the strut's travel without a spring (feels fine), re-torqueing everything on the rear sway bar, etc. Everything feels totally fine, went for a drive & sure enough, "CLUNK". So....I'm ready to give up. I'll buy someone all the beers if they can track down the source of this damn clunk. For real. Who wants to be my new best friend?

 

Check the endlinks connected to your LCA. Mine clunks whenever I go into my driveway.

If not, you may have the same thing I'm experiencing on my miata.

 

TopHat? Seen them fail before

 

I also have this same noise on my Bugeye wagon. Sound intensified after changing from 235/40-17 tires to 225/45-17 tires. I figured the slightly taller tires were hitting part of the inner rear fender on suspension compression. Now I'm beginning to think it may have something to do with the endlink and/or sway bushing.

 

^^^This, plus check the bearing nut as well. I also have a clunk from my right rear, not all the time, but I can usually make it happen backing out of my driveway at an angle. Last time we determined it was coming from a joint on the rear brace (x-brace between strut tops and middle back seat bracket).

My mechanic uses this sweet tool that has 6x wireless microphone/stethescope tools you can attach to different parts and then drive around while someone cycles through the mics to see where the noise is coming from. Have to see what it's called - probably expensive.

 

It's called a chassis ear. Use it all the time when people complain about little squeaks or rattles in sti's and wrx's

 

Well, it wouldn't have anything to do with a LCA since it's the passenger rear wheel clunking. When I had the suspension all apart yesterday, I checked the tophat (Group N) and it still looks/feels brand new. And yes, I have a thick washer under the nut, as the Group N hats require.

New observation:

While driving around today with my 82lb tool box in the trunk, there was no knock. As soon as I took it out, it started again. Mind you, I know it's not the sound of stuff shifting around in my trunk because I already took the time to remove EVERYTHING back there for a test drive the other day & the knock was still present.

So, what suspension component would cease to knock when more heavily weighted? This is such a crazy, annoying riddle haha.

 

Which springs are on your car? do you have a scooby921 spacer installed in the rears?

The endlinks can also clunk if not torqued down.

Do you hear the sound only on compression or during rebound as well? Does the sound happen at the first drop INTO the pothole or only the way OUT of it? Or if using a speed bump, does it happen when riding up the bump or coming off it on the other side?

 

I have Swift Sport springs with STI rates (almost identical to JDM Pinks) I have 1/4" Paranoid Fabrications spacers in the rear

Checked all the end link bolts, all are super tight

The sound is on compression for sure, but only abrupt compression.

 

I'm guessing tophat at this point!

 

Find a friend with a familiar setup that can loan you his tophats and springs? Process of elimination.