0260B4U

I have a 2007 C6 Base Coupe (Manual) with around 50,000 miles that recently started to make a "clunking" noise from the rear end (can’t tell if it is from left or right side). It will occur over small inputs at low speeds. It also makes noise on a smooth road if the car lurches forward when I purposely do a hard shift.

However, I am NOT able to reproduce the noise with the car parked by pushing down on the rear end or pushing it forward. I also tried to shake the exhaust, but that does not reproduce the noise either.

I raised the rear end with a jack and tried to wiggle the rear tires left to right and up/down, but it feels tight. There is no slop.

I read through the forums and decided to change my differential fluid to the recommended Dexron 75W-90 (per the GM TSB). However, this did not resolve the issue.

I visually inspected all the rear end bushings and tightened the suspension bolts (sway bar, links, control arms) and everything seemed OK. I also sprayed some white lithium grease on the rubber bushings, based on another thread comment. However, the car still clunks.

Does anyone else have other suggestions of what to look for or try? I don’t want to take it to a dealer, because I know I can fix it myself once I find the noise source. I just don’t want to start randomly replacing parts.

RekaRoyal

Have you ever re-torqued the rear axle nuts?

Good luck with the troubleshooting.

MurphMan2

Did you do this?

From the TSB;
"Once the differential fluid has been changed, the vehicle must be driven in 8-10 tight figure eight maneuvers to heat the fluid and allow the fluid to be worked into the clutch plates."

Jeff-Ford

Possible the rear end links need replaced

Bill Dearborn

That only resolves diff noises when the car is turning. When the car isn't turning both axles are turning the same speed and positraction clutches are not active.

Bill

0260B4U

I have not tried to tighten the rear axle nuts, but I will look up the proper torque and see what happens.

I did perform the 8-10 tight figure eights after changing the differential fluid.

I looked through the dealership history from the past 2 owners and it appears the rear sway bar links were replaced after 25k miles.

I just want to reiterate that I am not able to reproduce the clunk with the car parked when I try to bounce the rear end or rock it fore/aft. Does this rule anything out or point me in a certain direction? I am thinking ball joint, because I had a similar clunk noise on my 09 G8 GT and that was the fix.

Thanks for the suggestions.

Chevy Cust Svc

Hey 0260,

If there is anything I can do please let me know. If you want to send me your VIN I can see if there are any open service related announcements.

Kelly J.
Chevrolet Customer Care

Jeff-Ford

Your end links replaced at 25k and your at 50k now. Im at 24k and replacing all 4 when they get here. 30.+/- each is a cheap place to start.

0260B4U

Based on a suggestion from another thread I lubricated the half shaft splines and tightened the rear axle nut to 150 ft/lbs, but the clunk is still present.

My next step is to briefly disconnect the rear sway bar to confirm if the noise is eliminated.

Mad*Max

I have the same noise but mine is an A6 and I can experience the noise when shifting from D to R or R to D.

Be careful with re-tightening the axle nuts as they are supposed to be replaced and not re-tightened. Also, there are numerous threads on this and I read that you if you keep re-tightening you can break the axle.

thomaswat

Take him up on his offer ! There was a service bulletin out on mine. Had the same problem with my '07 automatic. They changed rear end oil and put in some additives and no more noise.

tondss

Did you ever find the problem out?
I'm dealing with this now myself.

David Petty

Any updates on this?

I'm having the same exact issue with my A6 (clunk only on hard shifts and shift down to first while stopped) - I'm pretty sure its the rear control arm bushings but would love a second opinion from someone who had same symptoms and fixed it

viktors94

I had this problem a few months ago, the dealer was sure it was the end links since they were stock and its a common problem. Replaced endlinks, swaybar bushings,lowering bolts, tightened all the controlarm bolts, tightened and locktited the rear axle nut but was still there.

Took it up on a lift again and saw a drop of oil coming from a rear shock and turned out that the left rear shock was shot and the cause of the clunking in my case. Each time the shock was extending it made a clunk since it had extremely fast rebound because it was blown.

whiplash1

My clunk (45,000miles) was the right half shaft joint was bad. Replaced the right half shaft and it went away.

RagTop69

Based on my vast experience with cars of much simpler technology than these, I would have a look at the universal joints. There could be some looseness in one of them making it clunk every time you put a little power to the drive train, taking up the slack in the worn joint(s). Or you could do eight or nine figure eights in the opposite direction and see if that helps.

Jose2SS

That same noise happened to me, I sprayed white lithium grease on the bushings and it went away, it started again a couple of months after that, my question is, where can I purchase the rear suspension arms bushings? Is there a kit? Help.

Thanks

Rick2008

I have a clunk from reverse to drive and back to reverse. What was your solution?

Red08

My thoughts exactly. I had a C6, and mine did the same thing. They may be installed tightly, both top and bottom of the end link, but they still may be loose within the link itself. Does it usually happen when going over a bump? That's when mine made the worse sounding "clunk". I replaced all four.

BMF_C6

I think you are going to find that your lifting bolt bushings have deteriorated and you are metal to metal.

I had the exact same issue.

Jack it up and check the ends of the jacking/lifting bolts on each end of the mono leaf spring, there should be a rubber bushing where it pushes down on the control arm, it's very hard to see. it will deteriorate and you will have a metal to metal clunking noise in the rear when the suspension flexes while driving.

I hope this helps
BMF