and you checked your tranny mounts/mounting brackets right?

 

Blau-parts is respectable and they usually have good prices, but i would still shop around if it's worth saving a few bucks.

I've got an issue with my front right and i can't figure out what it is. I'm sure i'll be ripping stuff apart trying to find it. Glad you got yours figured out. I know how annoying it can be.

 

Yep. Engine and trans mounts might be a bit tired, but not causing any issues. I'll be going for 034 mounts when I do a clutch. I replaced the rear diff bushings and installed the Stern Diff Power Ring. The center driveshaft definitely has too much backlash. At first I was scared the clunking was coming from the pinion bearing, but I found a clear issue with the driveshaft rear end joint, so I'll start there.

 

Just a thought...I had this happen and it was a rear transmission mount that had broken in half...felt like something was hitting the floor board under hard acceleration...

 

I think someone told me that if it wasnt the spare tire, it's the awd kicking in. the front kick in and then the rear.

 

I've checked all the mounts more than once. They will be replaced eventually, but it's not the source of my noise. I found a hard evidence the rear-most center drive shaft end joint is toast. If I hold the shaft in one hand and the companion flange of the rear diff in the other, there is a metallic clunk in the end joint. Additionally, there is visible backlash if I twist the end joints at either end in opposite directions.

So this is where I'll start. Unfortunately, the center drive shaft from Audi is a whopping $1250+ with no option of a rebuild kit. Blau-parts has a rebuild kit for $399 + shipping, but it appears as though it might be on intergalactic back-order. Grr. I'll give them a call Monday. Even if they have the end-joints and carrier bearing in stock, I'll take them. The clunk is bad!

Um...? If you're referring to the distribution of torque through the AWD system, it should never clunk violently like this. Additionally, under heavy acceleration, the Torsen sends more power to the rear. It's always driving both axles, never one then the other. It's a permanent Torsen AWD system, not "on-demand" or Haldex clutch-actuated.

 

ya he's right the awd will never ever clunk unless its broken

 

Update: Center drive shaft (prop shaft) repair kit ordered via phone from Blauparts. Nice, easy going guys. Hopefully will be here next week. I'll post a write up and results if I get a chance.

 

I received Blauparts' center drive shaft rebuild kit sometime at the end of September. I've had limited time to tear down my own car recently, but two weeks ago I had the chance to at least replace the two end joints, which were very easy. As for the carrier bearing and center u-joint, I couldn't figure out for the life of me how to remove the bolt in the center. Once I discovered I would need a press for the carrier bearing anyway, I decided against replacing these parts for the time being.

The result: I cured a vibration around 60-70 MPH. But it STILL clunks!


The rear end joint was stuck to the rear diff companion flange with an ungodly force. Prying, pulling, Zep Twister, cursing, and some beating with a dead blow eventually separated the end joint from the flange. The above pic is what I found. The grease was shot and had dirt ingrained in it. The joint itself felt sloppy compared to the front. I f anyone is interested, I can post a write-up of how to replace the center drive shaft end joints.

Replacing the center drive shaft rear end joint was definitely needed as seen in the above picture, but the CLUNK iS UNCHANGED! ;(

Here's what I know about the clunk:
-its getting worse
-taking off from a stop sign straight can be done smoothly with concentration
-taking off from a stop sign with the wheels turned yields several clunks from the rear
-shifting gears at any rpm can yield a clunk, but it can be sedated with concentration
-light throttle on/off while cruising at 3000 rpm yields a clunk
-running through 3rd and 4th gear both yield a clunk around 4000 rpm while WOT
-it's not the center driveshaft
-it's not an engine or trans or diff mount that I have observed or seen
-the suspension is tight
-there is nothing moving around in the car or trunk
-I've never felt this on another Audi

I've added the Stern Rear Diff Power Ring and the matching bushings. I've looked over every mount more than once.

More and more, it's looking like the rear diff or pinion bearing is bad. There is a high-pitched whine gear whine that increase with road speed. I was hoping to eliminate the possibility of a bad carrier bearing, but it's not a quick task to change. What baffles me is that the rear-end total backlash is well within spec.

I tried placing a camera under the car. No dice. I can't see any erratic or unusual movement of the drivetrain, exhaust or suspension.

Anyone have a rear diff laying around? I don't see any parts places for rebuild parts...

 

Any updates?