Clunking coming from the rear differential (not mounts)
AudiWorld Member
Joined: May 2009
Posts: 141
Likes: 0
So from what I gathered, the haldex system is basically a hydraulic locker for the rear end and requires a filter and fluid change every 30K miles. Problem is, it's on top of the diff and s bastard to get to. I think it was said in this thread that you can unplug a fuse to the system that'll help with the clunking.
AudiWorld Member
Joined: Dec 2014
Posts: 150
Likes: 0
From: Norway
So from what I gathered, the haldex system is basically a hydraulic locker for the rear end and requires a filter and fluid change every 30K miles. Problem is, it's on top of the diff and s bastard to get to. I think it was said in this thread that you can unplug a fuse to the system that'll help with the clunking.
AudiWorld Member
Joined: Jan 2003
Posts: 193
Likes: 0
Here is my experience with a clunk, in a nutshell:
Car:
1999 Audi A4 1.8t Quattro 5 spd
Symptoms:
Driveline clunk when engaging the clutch from a standstill, up / down shifting, and when lifting / applying the gas pedal.
Diagnosis:
- I assumed it was my rear diff mount, the big on that everyone replaces with Poly, but when I replaced my stock mount with poly the clunk was intensified.
- Then I replaced the transmission mounts since they were worn anyway. Essentially no change in the clunk.
- Then I got serious and actually crawled under the car to inspect things closely, rather than just throw more parts at it. I was specifically looking for play in CV joints and the rear diff (between ring / pinion). Without going into a lot of detail on how to do this, I was able to feel a bit of play in my driveshaft CVs (both of them). I didn't think the small amount of play would be the smoking gun, but by replacing both CVs along with the support bearing, the clunk was ALMOST gone. Probably 90%. My support bearing and mount looked bad, but not destroyed. I went back under the car and felt some play in the rear axle CVs, and on a whim put the stock diff mount in. Now the clunk is 99% gone. So, the poly rear diff mount was magnifying the driveline play that I had (and still have to a certain extent).
Solution:
To summarize the above, my center driveshaft CVs (1x front and 1x rear) and the driveshaft support bearing solved my clunk.
Car:
1999 Audi A4 1.8t Quattro 5 spd
Symptoms:
Driveline clunk when engaging the clutch from a standstill, up / down shifting, and when lifting / applying the gas pedal.
Diagnosis:
- I assumed it was my rear diff mount, the big on that everyone replaces with Poly, but when I replaced my stock mount with poly the clunk was intensified.
- Then I replaced the transmission mounts since they were worn anyway. Essentially no change in the clunk.
- Then I got serious and actually crawled under the car to inspect things closely, rather than just throw more parts at it. I was specifically looking for play in CV joints and the rear diff (between ring / pinion). Without going into a lot of detail on how to do this, I was able to feel a bit of play in my driveshaft CVs (both of them). I didn't think the small amount of play would be the smoking gun, but by replacing both CVs along with the support bearing, the clunk was ALMOST gone. Probably 90%. My support bearing and mount looked bad, but not destroyed. I went back under the car and felt some play in the rear axle CVs, and on a whim put the stock diff mount in. Now the clunk is 99% gone. So, the poly rear diff mount was magnifying the driveline play that I had (and still have to a certain extent).
Solution:
To summarize the above, my center driveshaft CVs (1x front and 1x rear) and the driveshaft support bearing solved my clunk.
AudiWorld Member
Joined: May 2009
Posts: 141
Likes: 0
Here is my experience with a clunk, in a nutshell:
Car:
1999 Audi A4 1.8t Quattro 5 spd
Symptoms:
Driveline clunk when engaging the clutch from a standstill, up / down shifting, and when lifting / applying the gas pedal.
Diagnosis:
- I assumed it was my rear diff mount, the big on that everyone replaces with Poly, but when I replaced my stock mount with poly the clunk was intensified.
- Then I replaced the transmission mounts since they were worn anyway. Essentially no change in the clunk.
- Then I got serious and actually crawled under the car to inspect things closely, rather than just throw more parts at it. I was specifically looking for play in CV joints and the rear diff (between ring / pinion). Without going into a lot of detail on how to do this, I was able to feel a bit of play in my driveshaft CVs (both of them). I didn't think the small amount of play would be the smoking gun, but by replacing both CVs along with the support bearing, the clunk was ALMOST gone. Probably 90%. My support bearing and mount looked bad, but not destroyed. I went back under the car and felt some play in the rear axle CVs, and on a whim put the stock diff mount in. Now the clunk is 99% gone. So, the poly rear diff mount was magnifying the driveline play that I had (and still have to a certain extent).
Solution:
To summarize the above, my center driveshaft CVs (1x front and 1x rear) and the driveshaft support bearing solved my clunk.
Car:
1999 Audi A4 1.8t Quattro 5 spd
Symptoms:
Driveline clunk when engaging the clutch from a standstill, up / down shifting, and when lifting / applying the gas pedal.
Diagnosis:
- I assumed it was my rear diff mount, the big on that everyone replaces with Poly, but when I replaced my stock mount with poly the clunk was intensified.
- Then I replaced the transmission mounts since they were worn anyway. Essentially no change in the clunk.
- Then I got serious and actually crawled under the car to inspect things closely, rather than just throw more parts at it. I was specifically looking for play in CV joints and the rear diff (between ring / pinion). Without going into a lot of detail on how to do this, I was able to feel a bit of play in my driveshaft CVs (both of them). I didn't think the small amount of play would be the smoking gun, but by replacing both CVs along with the support bearing, the clunk was ALMOST gone. Probably 90%. My support bearing and mount looked bad, but not destroyed. I went back under the car and felt some play in the rear axle CVs, and on a whim put the stock diff mount in. Now the clunk is 99% gone. So, the poly rear diff mount was magnifying the driveline play that I had (and still have to a certain extent).
Solution:
To summarize the above, my center driveshaft CVs (1x front and 1x rear) and the driveshaft support bearing solved my clunk.
AudiWorld Super User
Joined: Aug 2011
Posts: 2,369
Likes: 7
From: Washington
Im collecting everything to rebuild the driveshaft on my S4. GKN Lobro CV joints and a center bearing. After doing all the engine mounts, trans mount, and zero clearance snub, i still have some thunk in the middle to rear of the car it seems like. Im hoping this will solve it.
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