E46Fanatics - View Single Post - Strange Knocking under Acceleration
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Old 05-21-2012, 05:27 PM   #7
Registered User
Join Date: Oct 2008
Location: UK
Posts: 31
My Ride: E46 330ci Topaz
The Knocking Saga continues.......

So the knocking continues on. I have done some more investigation and have still not found anything substantive. What I have found is that it is definitely somewhere between wheel (rear left) and the diff. Having recorded the noise using my phones voice recorder. Looking at the file as a waveform, it was possible to time the knocking and after working out the wheels RPM at certain speeds and starting the knocking from a known speed I can calculate how often the knock should occur and compare the two. If the knock had been approx 2.93 times faster, it would have meant it pre-diff. Now it is certain that it on something between the tyre edge and the propulsion point for the left output shaft.
Does anyone have any ideas? There is now only a finite amount of things it can be. It only happens in high torque conditions. So this means it is either the torque itself there by leading to the CV joints, splined shaft, attaching bolts or wheel bearing. Or it is a product of the torque (acceleration) causing the geometry change in the suspension causing something to touch, once per wheel revolution.
It does count out things like the guibo and CSB though. In my original post it may have been misleading when I said drive shaft as well, the correct (by the book term) is output shaft.
Any words of wisdom are greatly appreciated, I am personally heading towards the outer CV joint at the moment but don't really go in for the willy nilly part change. So all received information will be thrown into the mix and a video recording will be made so I can post as it won't accept the *.mp3.
Cheers in advance

Last edited by Stanleyf233; 05-26-2012 at 05:51 AM.
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