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View Full Version : Its the "identify that sound" game


Luke318is
06-27-2006, 06:57 PM
Ok heres the deal.

The other day i was driving and noticed a "knocking sound" coming from the rear of the car. The noise is quite noticeable when on the highway. Its a knocking sound that increases as you speed up. It seems to show up when you take your foot off the gas pedal, and dissapear suddenly when you accelerate. Here are the possibilities and what ive done to eliminate some of them.
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PAssenger side CV Axle joint ==Eliminated, i put a new axle in. noise still there
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Tires (yes they are worn) ==Eliminated, i put a full size spare on and the noise was still there
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Drive Shaft? ==Eliminated, checked the drive shaft and everything seems to be ok.
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So the problems that i have not eliminated are:


Differential? ????My diff is worn. the shop thinks its a diff problem, but usually differentials whine or grind, has anyone ever heard a diff make ticking/knocking?
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Wheel bearing??? Possibility, but you dont hear the noise around corners, only when you "Coast" or decelerate. Usually wheel bearings are noisy around corners. The tire doesent have much play at all when moved side to side. And dont wheel bearings usually take a while to get this bad? this was a fairly sudden change.

Any help is appreciated because i dont have the cash to do both fixes. I need to somehow find out what the problem is so i dont have to shell out the cash for both the wheel bearing and the differential.

If i get a diff i am getting a LSD 325i diff.
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e30_kid89
06-27-2006, 07:39 PM
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Wheel bearing??? Possibility, but you dont hear the noise around corners, only when you "Coast" or decelerate. Usually wheel bearings are noisy around corners. The tire doesent have much play at all when moved side to side. And dont wheel bearings usually take a while to get this bad? this was a fairly sudden change.

not always true. some times wen u corner the wheel bearings will stop making noises. my 2 front ones went out and 258k so i replaced em...then i did one of the rears just for the fun of it:)

RobY330i
06-27-2006, 08:15 PM
Drum brakes?

Luke318is
06-28-2006, 04:36 AM
disc

bmdoubleya
06-28-2006, 01:12 PM
I would guess your cv"s

T.Dot_E30
06-28-2006, 03:06 PM
Diff mount, sub frame mounts, swaybar links. RTABs (Rear trailing arm bushings)

That would give ur rear suspension a nice refreshment.

Woofer
06-28-2006, 03:58 PM
i have the same sound


Its more of a clicking sound. I have come to the conclusion that its either my rear shock mounts. Rear shocks or sway bar end links.

Alotof people have also told me it could be my emergency brake assembly.

Luke318is
06-30-2006, 06:33 AM
Its something that "spins" for sure....and i replaced the CV axle ....noise still there.

I think im going to do the wheel bearing next...if its not that it only leaves the diff i think.

I could be wrong though

Luke318is
06-30-2006, 07:08 AM
i have the same sound


Its more of a clicking sound. I have come to the conclusion that its either my rear shock mounts. Rear shocks or sway bar end links.

Alotof people have also told me it could be my emergency brake assembly.


checked my shocks...they seem quite fine. ill check the other stuff i guess.

What a weird @#$@# problem. its pissing me off.

biotek
06-30-2006, 11:28 AM
take off the rear rotors and check your ebrake, i had 1 side go one day and the other side go the next lol, no e-brake for a week now lol

Luke318is
06-30-2006, 03:57 PM
take off the rear rotors and check your ebrake, i had 1 side go one day and the other side go the next lol, no e-brake for a week now lol

Good call, but we did that as well.