Any Ideas Please ????

    My car drives beautifully.
    No clonks or squeaks.
    BUT - I still have a rear end rattle/knock.
    It sounds like the exhaust hitting something.

    • Exhaust checked - held firm, can't get it to make contact however hard I pull/push it.
    • Rebuilt EDC shocks.
    • New top mounts - checked and tight with reinforcing plates attached.
    • Reinforcing plate is not catching top of shock.
    • New roll bar drop links.
    • New trailing arm bushes.
    • New top links.
    • New springs.
    • Brakes appear firmly attached.


    I checked the other bushes as best I could when I had the springs out (so nothing was under tension).


    You can hear the knocking here:
    http://www.youtube.com/watch?v=Ou5YuS7-a5Y
    You can see why I thought it was the top mounts - they were worn, but the knock is still there!


    I know I've brought this up before, but don't know what else to try other than changing all the other bushes - which I simply can't afford at the moment.


    Any suggestions - no matter how speculative - will be very welcome.

    Have you tried removing the rear seats just in case the knock is coming from them moving on the catch? Is the amplifier secure? Is the jack secure? Batteries clamped down?

    Thanks for the suggestions :) All welcome :)

    Batteries clamped down tight and jack snug.
    Yes it does sound like top mounts - but they're brand new and fitted correctly and tight.
    I suppose it could be baffles - but would need to be a large heavy chunk to knock rather than rattle.

    I haven't checked the diff mounts - will look at that - thanks.

    More ideas very welcome......

    Think I might try and set up some video/audio from under the car while running......

    Hello UKZero !


    Amongst many other knocks and rattles I isolated, I found that one irritating noise/rattle came from the rear brake disc protective shrouds that fix between the discs and the arch.


    After having new brake pads fitted, I was plagued with this noise everytime I drove over the slightest of bumps on urban roads (couldn't hear it at speed due to road/wind/engine noise). Turned out that they had been incorrectly refitted and although not loose, they just needed adjusting.


    This might not be your problem, but thought I'd share it just in case !

    Hi Tony - good to see you're still looking in from time to time :)


    What I really need is that suspension testing device shown in the E31 development photos!


    All good ideas chaps - will look into them all when I can.


    Keep'em coming :)

    Zitat von koenig dave;93162

    UKZERO; have you fitted the Reinforcing plate?
    inside the boot ?
    or under the car ?



    Inside the boot - wouldn't make sense to me to put it underneath - but I'm prepared to be corrected :hmmmm:

    Again - thanks for the ideas :)

    Zitat von 8Tech;93266

    Try removing both rear shocks completely and go for a short ride over a bumpy surface. At least that will eliminate or confirm whether it is the suspension or not.


    I suspect the strut.


    8Tech.


    Good idea Gerry. Thanks for that.
    Will give it a go when I get a chance.
    I'm sure it did it before I had the EDC shocks rebuilt as well as since, but it doesn't sound like a bush (unless the rubber had all gone!) and the shocks were "only" rebuilt - so aren't new as such and can't be excluded from suspicion. Hope it's something else though :pray:
    If not that I'm leaning towards a ball joint as I believe there are at least a couple in the rear suspension somewhere.

    Zitat von 8Tech;93351

    A couple!!! Dream on.


    Try 8 balljoints and 6 bushes PER SIDE.


    Oops! Showing my ignorance again :roll:
    I could only see a couple on each side at the rear (the ones that look like track rod end type ball joints).


    Is there anything they didn't over engineer on these cars :hmmmm:
    Apart from heater matrix plastic pipes, seat reclining handles, erm...

    Main ones to look at are.......


    Inner and outer balljoints on the upper arm, especially inner.
    inner and outer balljoints on the lower arm, especially outer.
    Front bush in rear trailing arm.


    and I'll not mention the top strut mount cos you replaced that and added the reinforcing plates, right?


    Oops, mentioned it! :hmmmm:


    The rest are pretty robust but I fit a LOT of the above.


    8Tech.

    Thanks again Gerry.


    Just to recap, I have fitted:
    New front big bushes in trailing arms.
    New strut mounts (with your reinforcing plates).
    New top links (the expensive ones with integral inner joints) - did these 'cos my local BMW dealer took pity on me and gave me a massive discount (much to my amazement) - Oh and they were knackered.
    New roll bar drop links.
    New springs (not that the broken ones rattled, more of a "b'doing!).


    I recon I might consider changing the other bushes you mentioned as a matter of course over the next few months.


    Driving over those ridges you get on the approach to some roundabouts on dual carriage ways the other day I noticed that the whole rear of the car felt, well loose.
    No crashes, bangs or knocks (can't hear the annoying rattle at speed), not bouncy either, just loose.
    Do these cars suffer with problems relating to diff carrier or rear subframe bushes?


    I've decided to keep the car for a while yet, so will keep replacing bits until it's sorted :)

    That rear twitch is usually the front bushes in the trailing arms but you replaced those right? What with because the 850i and 840i ones are a lot softer than the CSi or my urethane ones?


    The only other thing I can think or would be the rear subframe bushes but that would be a first. I have never seen failed ones of those.

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