invadermoose

Car is a 2008 C6 Base A6. My car has been making a horrible groaning sound when I take right turns. Not even hard right turns, just right turns. No issue when I turn left. I want to clarify now that I already did the very often recommended diff fluid change

Today I set out to figure it out. I inspected everything and gave up figuring I'd just come back another day, but when I was torquing my passenger rear wheel I noticed the wheel was popping when I was approaching 100ft-lb. I torqued everything to 110 and rocked the rear wheel by hand. Every time I rocked it, it would pop. The car is an auto, it was in park, and the e-brake was off. I felt around and it feels like the pop is happening directly under the CV boot closest to the wheel. If I put the car in neutral it pops but its so quiet that its hardly noticeable and can no longer be felt. I repeated all this on the drivers side and it did not pop anywhere.

So now I'm trying to figure out if its my CV joint or my rear diff, and I dont really know where to begin. The CV joint looks perfectly fine under inspection. No spilled grease and the boot is not damaged. If I put my hand on the boot near the rear diff, the pop cant be felt as easily, which is why I suspect the CV over the diff. I changed the diff fluid according to a TSB a few months ago and it did not fix the issue, and at 42k miles I have no reason to suspect the diff has any reason to have failed.

AlSled

Dutch08

I have no clue, so just some information that may help.

2005 M6 42,000 miles. Just fine except for a very low speed pop or muffled clunk that was hard to hear. Only way to make the noise was to take off from a start just right. Two new rear shafts later no noise. The old ones looked just fine.

WW7

I have never had the problem on my C6 , but I did have the popping or clicking noise on my C4 and it was the universal joint that was bad.. With the car off the ground and in park, you should be able to have someone move the wheel back and forth and feel the universal joint moving/popping in the shaft...WW
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invadermoose

So I decided to steal my wifes stethoscope. Turns out the noise is coming from directly beneath the boot of the rear cv joint. The boot near the wheel specifically. I put it up to the centercap and it wasnt as loud.

I just have never seen a bad cv joint that wasnt leaking. I also have never seen a bad wheel bearing that didnt have play in the wheel.

I'm concerned it may be the diff, but I cant find a single video online off diff issues which sounds like what I'm experiencing. Also, why would the diff even make a noise just from rocking the wheel? I feel like the gears wouldnt move enough for it to do anything. I dont think its the universal joint or anything near the torque tube because it would probably make a noise going straight too

3X2

Axle nut tight?

invadermoose

Actually just last night I found a thread where someone had a problem just like mine and it was the Axle nut. I ordered a 33mm socket so I could find out. I checked to see if I could turn it with my hand but it isn't quite loose enough for that. Hopefully this solves it

xBoostx

If it was the diff will likely make the noise all the time going down the street check the axle nut if tight then likely is the wheel bearing if there's play in it observe closely where the play occurs so you know where the problem is, good luck pls let us know so that others can benefit from your experience.

Always be sure to use tire chocks and jack stand never trust a floor jack.

3X2

I always use red loctite on those nuts when re installing them.

Jerry0

I fully agree with 3x2 had same problem on my 05
replaced axel nuts,, did diff service clunking gone ..good as new

Unreal

Had this twice. Axle nut, and 2nd time was end links.

Higgs Boson

my 17 Z also does this, not the ackerman tire skipping, backing out of garage, might coincide with the one inch drop from garage to driveway? not really sure. sounds like something is loose though.