I've been through many dozens of threads here on suspension clunks because I know I'm not the first to see these issues. I have an 05 z51 m6 with 200k on it. The clunks started suddenly one day and have steadily gotten worse. Any irregularity in the road, and it's noticeable.

First go-round I replaced the sway bar end links on the rear (sounds like it's coming from there to me). The ones that were on there were definitely toast. That didn't make any difference in sound at all.

Started at it again over the weekend after reading many more CF posts and decided to check the wheel bearings/tie rod ends. The passenger side wheel I could tilt back and forth maybe 1/8" at the 12/6 position and no movement at all on 9/3. Driver's side: no movement either way. I know this generally points to wheel bearing but I saw/heard zero other symptoms that normally accompany a wheel bearing (howling, getting better going one direction etc.).

The shocks may be noisy but there is no extended bouncing going on at all. Ride is not harsh or too soft. I have the GM records on the car (PO's MIL owned a Chevy dealership and had all the work done there) so will check that to see if they ever have been done.

I did get a new axle nut for the passenger side to make sure that wasn't the issue. The threads were quite rusty and took a big cheater bar on the breaker bar to break loose so I'm thinking it's not that. I put the new axle nut on with blue loctite and ran it up to 140 ft/lbs. I can confirm that for my 05, it was a 33mm nut coming off, 34mm going back on. My 3/4" hobo freight socket set has 20something, 32, 35, 36 38 etc. Neither the 33 or 34 that I needed

Anyway, ran out of time tonight to go drive it around the block to see if the noise is any better. Will report back tomorrow after work but I'm not anticipating any improvement.

Any ideas for what to check are appreciated

Thanks all!

 

Is your car lowered with aftermarket bolts?

 

I don't think it is. I've seen quite a few cars lowered and this one seems to have quite a bit of clearance in the wheel wells.

 

OK. Mine is lowered and I was having " clunking " issues with the suspension and after doing just about everything you did the fix was a dab of grease under the suspension lowering bolt pads, fixed the noise for several weeks and at the first sign of a " clunk " I know its time for more grease.

 

I'll take a look. Worth a shot

 

Here's what's in there now. I'll do some searching on lowering to see if I can find a post with stock & lowered from near the same angle.

 

Those are the factory bolts, I doubt that is your issue but if you support the suspension and then jack up one end at a time on the leaf you will make a gap under the pad to squirt a small dab of grease. Worth a shot as it only take a few minutes.

 

Is it possible to catch on audio?

 

I can try to record with my phone this afternoon to see if it picks it up.

No real change that I could hear after the new axle nut.

I'm planning on popping off the front sway bar this afternoon to see if those links are as shot as the rears were. Maybe the noise is from the front. Still feels more like rear to me but

Went through all of the info I got from the Chevy dealer on the car and there was no mention of shocks being replaced so will probably go ahead and order a set of the Bilstein B8s. Found a set for under $400 shipped

 

Could very well be the shocks. at 12 years and 200k, the upper rubber bushings have probably hardened plus the shocks are probably worn. It is hard to tell on these cars due to the springs, not a lot of bounce to them. Shocks are relatively inexpensive and not too hard to replace. You could try to tighten the upper nuts on the shocks to see if there are any changes to the noise level.

 

I've pretty well decided that the shocks are the only things left under there that could allow that noise. I checked the front sway bar end links today and was pleasantly surprised to see I'd replaced them when I did the rears. I must be getting old because I didn't remember that I'd done all 4 at the same time

After an aggressive drive this afternoon to try to smear that grease under the rear lowering bolts and no change, the shocks are the only thing that makes sense to me. Maybe they've lost their damping ability and they're bumping against the springs/stops/whatever.

I agree too that 200k on stock shocks is overdue. I'll order a replacement set and report back.

FWIW: ajusa.com has the B8 Bilsteins for ~$96 each shipped.

 

I was chasing what I thought was suspension popping and creaking noises for about 3 months. The noise was driving me crazy. I replaced the end links, new shocks and lowering bolts. Torqued everything to spec. The noise was still there and sounded like it got worst. Got in touch with Mark @ MSI...…….Turns out it was the roof creaking and popping...……. its fixed now.

 

I've been driving it all weekend and this morning to work topless and no change in noise. Fun to drive with the top off though

 

I have Delrin upper shock mounts on mine and I'm always chasing a fine line between just snug enough so they don't bind and not make rattling noises when going over bumps. I can go over bumps and tell which shock mount needs tightening.

 

Haven't looked at loose shock bolts as a possibility. I'll have to check that out after ball tonight