Annoying knock/rattle - Video evidence!

    Is this the not very loud, but oh so annoying knock/rattle I can hear from behind me?
    Video shows OS rear top shock mount.
    Q1 - Should a healthy top mounting bush move this much on a smoothish road?
    Q2 - I can hear the noise and it seems to be in sync with the movement - but can you?
    Q3 - Is the noise something else entirely?

    Views (pardon the pun) and opinions welcomed :)

    View and listen here:

    http://www.youtube.com/watch?v=Ou5YuS7-a5Y

    Zitat von earl198;92211

    Try removing the reinforcer plate, I had a similar issue



    That was my first suspicion - but on close inspection I could see no evidence of metal to metal contact. The paint on the reinforcer rim was unmarked.

    Given the relatively low cost of new rubbers I'll swap these anyway and use a slightly smaller top washer as well to incorporate your insight. Thanks

    I've just got my car back from having the rear bumper removed and resprayed to update the hideous OEM PDC units - will unveil at Duxford :harhar:


    While the car was on the lift in the garage I spent some time trying to find what was causing the knock/rattle from my OS rear end.
    We couldn't find any worrying play in any suspension components.


    On the road the noise now sounds exactly like a loose exhaust system rattling against something, but I can't reproduce this under the car no matter how violent I get.
    If it's an internal baffle the weight of the knock suggests the whole internals of a silencer have come loose as one lump :hmmmm:


    Next plan is to tape a cheap video camera to different under-car components as I drive along!

    I had a similar knocking in my 840. I suspected the top mounting bush also. Changed it with a new one, but it made no difference.. I had it at my local workshop, but they couldent find it.. they suspected the exhaust! I took a closer look myself. It was really hard to find, but it turns out it was a bushing. Number 2 on the picture. Only one made the knocking, but i change them all, as they where pretty soft.

    Zitat von TERMINATOR;98136

    I had a similar knocking in my 840. It was really hard to find, but it turns out it was a bushing. Number 2 on the picture


    Thanks very much for this info. This sounds very promising!
    There are two "Number 2" bushings in the picture, one at each end of the lower arm. I might change both, but which was knocking, the inboard one or the outboard one?


    Thanks again :)

    The outboard was making the knock noise on my car. It was not easy to locate the noise , it was when i twisted number 1 on the picture i could see and hear metal hitting metal.

    it's not how many miles on a tank,
    but how many smiles;-)


    Svein


    1993 840ci/6 Supercharger

    Useful pointers here. I have a similar noise which I cannot trace so I think I will check the rear lower arm bushes when I change the upper arms in a couple of weeks.

    T, could you rock the lower arms by hand?

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