jaimesonlee

I agree, I am eventually gonna have a stealership inspect mine if I don't get it figured out.

trevor51590

Just wondering if there was any update here.


As of now I have replaced:

Motor mounts
Snub mount
Transmission mounts
Apikol rear differential mount
Rear differential stabilizer bushings

I still get the thud, and Im not sure where else it could be coming from. I think it may be the driveshaft at this point. The center u-joint was solid as a rock when i checked it. The rubber around the center support bearing looked like it has slid down the shaft a little bit and it was fairly soft.

One thing I also noticed is that if I reverse, I hear a clank. When I put it back in gear and accelerate after reversing, I sometimes also hear the clank.

I just want the car to drive nicely again. Wheel bearings, control arms, and new suspension are all in order too :/

jaimesonlee

Maybe this perhaps?

http://www.ecstuning.com/Audi-B5_A4-..._Joint/ES2870/

ricekikr

update?

BlkBullitt

Actually the driveshaft (or propshaft) that runs from the transmission to the rear differential consists of 2 CV joints (one at each end), a center carrier bearing, and a center u-joint. It is more common for the center carrier bearing and / or u-joint to go bad vs the CV joints. Just drop the exhaust, take off the heat shield, and give the driveshaft a good shake (the rubber in the carrier bearing should prevent it from moving excessively). Also, check for slop in the u-joint by grabbing the front piece of the driveshaft with one hand and the rear piece with the other hand and try to move them in opposite directions. The u-joint should not allow any movement and should remain tight.

Do check both the carrier bearing as well as the u-joint as both can be bad (trust me you don't want to replace one to find out the other is also bad).

Also, some driveshafts have u-joints that are pressed and crimped into place making them extremely difficult if not nearly impossible to rebuild.

jaimesonlee

Thanks for that info! I am going to do that, just procrastinating.

E36B5

Any new updates? Over the last couple years I have checked and double checked mounts, u-joints, ect. Had a couple shops check it out too. I'm starting to think its in the transmission, that is where the rotational looseness on the driveshaft is comming from.

jaimesonlee

I am getting a new transmission and rebuilding the engine and during the time of install I am going to find out where the hel it is coming from.

gilram01

i have had the same thud noise on my 2.8 a4 quattro. replaced all 3 rear diff mounts and at the same time found my carrier bearing messed. the thud noise was corrected after i replaced the rear diff mount at the front of the rear diff. if you have a vibration and thud noise happening chk the drive shaft and center carrier bearing. stealership charges close to $1400 for a new drive shaft. there is a place in dallas, texas that can rebuild your drive shaft and replace the center carrier bearing. turn around time is 2-3 days they stay busy.

JPW1

PROBLEM FINALLY SOLVED

After living with the clunk for many years, I finally got it into a good shop. They diagnosed it as a bad differential. New Audi differential is $3500. The shop found a used diff for $350 including shipping. Wow what a huge difference. Feels almost new - and with 250K miles on my A4 that is saying something.

Thanks to Tom and Walt at Everything Euro in Winston Salem NC - best independent shop that I have found.