B7 Quattro - The impossible vibration
Discussion
I posted regarding this issue back in April - https://www.pistonheads.com/gassing/topic.asp?h=0&...
It's becoming a bit of a saga if I'm honest. Here's the run down of events so far:
Initial Clunking/Thudding Noise - Noticed this back in April, when accelerating through 1st/2nd gear there was an occasional clunking noise, some times a bigger clunk when changing up from 2nd gear. Only happened under load at low speeds, once road speed reached 40-50mph it went. Worth noting that when manoeuvring at low speeds, parking etc. there was scrubbing/vibration from the rear tyre area.
Initial Diagnosis - Took it to the local VAG specialist and was told it was all down to my rear diff. Sourced a second-hand unit and got them to fit it. Immediately the noise became quite a violent vibration, interestingly happens under the same conditions - 1st, 2nd gear up to around 40-50mph. It's directly related to throttle, the more applied the worse it gets, once I let off it goes and the car will coast silently, there's no vibration at higher speeds.
Everything since then - The specialist currently has my car, they've changed the propshaft centre bearing to no avail. They've stripped my original diff and it's transpired to be fine all along. Specialist is telling me all CVs/UJs are fine. They've suggested that the Dual Mass Flywheel might be the cause, but the fact the noise was previously a clunking puts me off this idea. Another thought I've had is engine mounts, I had a health check done and one of the things noted were leaking engine mounts, my thinking is maybe the engine mount is allowing enough movement of the powertrain to put excess stress on another joint/component?
Cheers for reading, hopefully someone has had something similar in the past, it's got myself and 2 garages stumped at the moment
It's becoming a bit of a saga if I'm honest. Here's the run down of events so far:
Initial Clunking/Thudding Noise - Noticed this back in April, when accelerating through 1st/2nd gear there was an occasional clunking noise, some times a bigger clunk when changing up from 2nd gear. Only happened under load at low speeds, once road speed reached 40-50mph it went. Worth noting that when manoeuvring at low speeds, parking etc. there was scrubbing/vibration from the rear tyre area.
Initial Diagnosis - Took it to the local VAG specialist and was told it was all down to my rear diff. Sourced a second-hand unit and got them to fit it. Immediately the noise became quite a violent vibration, interestingly happens under the same conditions - 1st, 2nd gear up to around 40-50mph. It's directly related to throttle, the more applied the worse it gets, once I let off it goes and the car will coast silently, there's no vibration at higher speeds.
Everything since then - The specialist currently has my car, they've changed the propshaft centre bearing to no avail. They've stripped my original diff and it's transpired to be fine all along. Specialist is telling me all CVs/UJs are fine. They've suggested that the Dual Mass Flywheel might be the cause, but the fact the noise was previously a clunking puts me off this idea. Another thought I've had is engine mounts, I had a health check done and one of the things noted were leaking engine mounts, my thinking is maybe the engine mount is allowing enough movement of the powertrain to put excess stress on another joint/component?
Cheers for reading, hopefully someone has had something similar in the past, it's got myself and 2 garages stumped at the moment
Front engine mount would be something to investigate as the engine is inline and going on/coming off the throttle makes the engine rock and can shunt down the transmission.
Rear diff mounts should also be looked at.
The leaking engine mounts wont help and should be replaced. The replacement rear diff, did this have new mounts/bushes when fitted or just the ones it came with?
Rear diff mounts should also be looked at.
The leaking engine mounts wont help and should be replaced. The replacement rear diff, did this have new mounts/bushes when fitted or just the ones it came with?
Edited by anonymous-user on Wednesday 23 October 20:57
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