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Occasional "Pop" coming from the rear?

Discussion in 'E46 (1999-2006)' started by mwurman, Sep 16, 2013.

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    mwurman

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    So every once and a while when I'm starting off after being parked, I hear and feel a "pop" coming from somewhere in the rear. Sometimes its more substantial than other times. It happens AFTER i've been rolling. The one time it happened I was about 1000 feet down the road after pulling out of my driveway (about 30mph), and today it happened after about rolling 20 feet in a parking lot. Once i'm going, I can start and stop with no further problems. It started after I replaced the rear brakes this past week, but i'm not sure it has anything to do with that. I know my "drum style" emergency brakes are in bad shape. Is it possible that one could be jamming/seizing and then popping in or out of place at random? They're pretty much loose and worthless right now. I have to pull all the way up on the lever and even then, they aren't effective.

    Other things as well. Rear suspension is new. Bushings and joints on everything are tight. Springs and shocks both replaced in the past 20k miles. Not sure if its a drivetrain issue since I have no vibrations at any speed, and when you get on it, its strong. Always have maintained the differential fluid. Drive axles look good. Maybe the drive shaft guibo(s)? Subframe also looks good and feels strong when cornering and accelerating...I doubt that would be a problem since I have a 'vert and thats vary rare of a problem from what I've seen.

    Lastly, I noticed when i was at the shop on friday, the mechanic (a friend of mine whos owned and worked on 3 of these cars) had to jack the rear of the car up to get the lift pads underneath. Usually when I jack the car up I put the big jack under the big frame under the diff. I noticed he put it on the metal plate further back. I circled the spot on this picture:

    [IMG]

    Would that cause something to go wrong?

    So thats alot I know...but any ideas? Thanks!
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    steven s

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    Sounds like parking brake shoes to me.
    Could be as simple as removing the rear rotors and lubing where the shoes slide.

    I trashed my e-brake several years ago and finally replaced them myself on my E36.
    Not too difficult for a DIYer.
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    Terry Sayther

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    Does the pop noise happen after sitting and USING the handbrake? Or just parking and sitting without emergency brake use? If it happens only after handbrake use, then I'd say the handbrake is involved. Especially if you observe that there are worn parts there.

    Rule of thumb: fix the known problems first, then look for something more exotic.

    Second rule of thumb: when you hear hoofbeats, think horses not zebras.

    If no handbrake use is needed to make the noise, I'd suspect something else. Rear differential mount is a common failure. Rear upper shock mounts commonly fail, esp if they were not replaced hen the Bilsteins were installed. Also, of course you'll need to look at the floor of the car where the rear suspension bolts on to see if the sheet metal is tearing out---try to avoid having that problem!
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    steven s

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    But...
    Problem started after replacing pads and rotors.
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    Terry Sayther

    Post Count: 107
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    No argument. Seems like problem started after rear brake replacement, therefore most likely because of something done during that operation. Most likely directly related to brake replacement, but the rear suspension was also disturbed in that job, so those other things are also possible. As are other, yet undisclosed possibilities.

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