Any hints for dampening vibration sounds? I hear one that seems like it’s coming from the parcel shelf, but sounds like the thin heat shield on my old pickup.
Thanks in advance.
Hello - you can try products like Dynamat and Hushmat.
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Metal on metal is strange to have in that area because just about nothing is back there that could make the noise. Did someone maybe add a bracket underneath it for an aftermarket amp or something? That'd be my first guess
-John
Loose speakers? Panel clip popped loose? Loose rear seat back screws letting it vibrate? Perhaps pull the rear seat and speaker panel and drive around to see if the sound goes away?
I'd suspect the exhaust heat shield, either in the back by the muffler/halfshafts or the one between fuel tanks.
Max
1981_bmw_320i_1543801871ef66e7dff9f98764daIMG_5976.jpg
Do the flanges with threaded holes suggest anything that might cause more vibration?
No these flanges are for a little heatshield that is missing.
There is a pipe heatshield in front of it that is tack welded to the pipe and often starts rattling when gets hot.
Hum sounds like like tire noise or a wheel bearing. Could be a differential too. Nothing should be making humming noises and "fixing" it with dynamat is not a solution ( it will not quiet it down much anyway).
Max
It 'hums' at 65 mph or above, at 3500 rpm or above. Really like a harmonic frequency from the engine. I hear nothing at all at lower speed.
I do have doubts about dynamat.
M10 itself is noisy and kind of "hums" above 3500 PRM... Hard to diagnose without hearing it. If it's speed related then it could be tires, wheel bearings, driveshaft, differential or transmission (unlikely especially for auto). Noise of the wheel bearings and tires change depending on turning.
If it's RPM related than it has to come from the engine.
What did you drive before this e21?
Max
'79 VW Rabbit diesel. That is loud!
I had wheel bearings go bad - I'd describe it more as a 'whirring' noise than a hum.
Could be the drivetrain, though. Like the diff, but I think it's the engine and exhaust.
When I've had bad wheel bearings one thing I noticed was the sound would be more or less noticeable when I was turning right or left.
I have been trying to figure my road noise above 65 mph out also. Old post below
https://www.bimmerforums.com/forum/s...ar-Wheel-Noise
Could be rear bearings ?
bad engine mounts ?
https://www.youtube.com/watch?v=5xGH...&frags=pl%2Cwn
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