So my E36 M3 coupe has been making an obnoxious knocking noise in the rear, I originally suspected the RSM were done for (which they were) so I decided to refresh my suspension as the OE suspension had 250k on it. However when I replaced the RSM and the suspension the knocking noise remained and is still quite annoying. I suspect that the Rear control arm bushings are to blame as all the bushings need replacement, however, before I go out and do this I would like some other opinions on this as I simply do not know for a fact. I would like to get rid of this noise before doing all the other bushings.
Can you describe a bit more as to when the noise occurs? Is it when you're driving a certain speed or in general, idling? Any more details will help. Have you checked out the tie rods?
Dmitry is correct, we would need a lot more details to narrow down suspect part(s). One way would be to get your coupe on a lift and have a thorough inspection done on your suspension. Maybe even using a prybar to manipulate bearings,bushings,swaybars,endlinks...etc. Don't disregard exhaust as a possible cause of knocking noise.
Former owner of RacyRed - RL411
The noise only occurs when I hit a bump in the road or when the road is uneven, it is like a heavy knocking noise and it is most prominent on the passenger side right under the rear quarter panel.
It is very difficult to give an accurate diagnosis from a vague online description, but since you insist on continuing without a visual inspection for confirmation, here it is- you describe the noise in the general area of the passenger side rear quarter panel, so I would start by replacing swaybar bushings and endlinks , #2 pictured here:https://www.realoem.com/bmw/enUS/sho...diagId=33_1963
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If noise persists, continue with replacement of RTAB bushings, upper and lower balljoints, to finally rear subframe bushings. I must ask, were the RSMs installed correctly along with the new shocks,bumpstops?
Former owner of RacyRed - RL411
If you plan on keeping the car a complete refresh would be money well spent. It likely needs or will soon need everything replaced anyways....and you would be amazing how much better these cars feel with a full front and rear suspension refresh!
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I am so sorry for the late reply! I have been busy as of late with moving and what not.
I think I will start with the sway bar. I am planning on getting under the car soon and tinkering around seeing if I can find the direct source. Sorry, I am using my phone so I can upload a pic of the underside when I get the chance.
All the bushings are pretty shot, I am stuck between OE and Poly bushings, I want the car to be comfortable so really that is the only thing holding me back from Poly bushings.
Sorry for the late reply, I have been busy preparing to move and studying for finals.
Yeah, honestly I know that so many bushings need to be replaced that it makes it harder to pin point the location of the noise but it is definitely in the general area of the swaybar, il get under the car tonight and play around with it.
Yeah, my friend has an M3 that had all bushings, endlinks, etc. Replaced and it is literally comparable to a new car!
I am debating doing Poly bushings but I don't know for certain since I know that they do sacrifice comfort for performance, I mean this is my daily so OE would be the way to go???
You might have a cracked subframe around where the rear sway bar mounts. My car had all the same symptoms. An easy way to diagnose sway bar issues and clunking is to simply disconnect the rear sway and take it for a ride over the same road that causes the clunking noises. If gone, solved. Then I'd inspect the exhaust hangers.
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PCA HPDE Instructor
1995 BMW M3
2003 BMW 540i6 Alpine White M sport