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Thread: Rear end thud

  1. #1
    1st Gear

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    Rear end thud

    Hey guys,

    I have a thud coming from the rear end on the last thirdish of the clutch pull out in first. It doesn't always happen but I think is becoming more frequent. Only seems to happen in first.

    Any ideas. Oh I have 4wd

    Cheers

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  3. #2
    Bradderz_1988's Avatar
    Dont replace it, Upgrade it !!

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    Rear diff carrier bushes or centre diff mount worn out or what mine was the bolts come loose on the diff carrier.
    1999 Audi A4 1.8T Quattro Sport - Volcano Black

    Mods - Frankenturbo F21 Kit - 3" MAF - Saab Reds - THS Decat - Non Res Milltek - ECS Crank Pulley - 034 Snub + Bracket/Gbox Mounts - 1Z/S2 Clutch + Flywheel - 007p - ICM + EVAP Delete - PFR6Q Plugs - S4 B6 345mm Brakes - 300mm Rear Brakes - Goodridge Hoses - LCR Splitter -S4 Bumbers + Skirts/Mouldings - OEM Xenons - Apikol Diff mounts - Polytek'd Rear Diff Mount
    To do/planned -Eibach pro's - GT2871/76R + FMIC + ME7 (maybe) + Engine/stroker Build

  4. #3
    Chriscooke's Avatar
    Clueless!

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    My dif clonks every so often, doesnt seem to affect the car much yet though.

  5. #4
    1st Gear

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    Quote Originally Posted by Chriscooke View Post
    My dif clonks every so often, doesnt seem to affect the car much yet though.
    Lol. I think I would rather get it sorted first rather than keep it happening then she goes

  6. #5
    2nd Gear

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    I agree with brad on this. Check all bolts are tight before you go replacing anything.

  7. #6
    Chriscooke's Avatar
    Clueless!

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    Mine was checked by the previous owner at a vag specialist so I'm not overly worried.

  8. #7
    "Stick a V8 in it!"

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    I've been chasing this for a long time.

    I've found numerous issues, and changed various parts, but its still there.

    If your lucky its just the rear diff mountings. With mine, i upgraded the rear diff mountings and made everything nice and solidly mounted, and the problem got worse, with a really horrible metallic clank in 1st 2nd and 3rd gear when engaging the clutch.

    I swapped the rear diff out for a spare, still the problem remained.

    I've since swapped the gearbox, replaced a couple of CV's which had play in them, and swapped the upgraded rear diff mounts out for softer ones, which has made it less harsh and bareable, but STILL present.

    Its most noticable now when lifting off the throttle or reapplying it once moving. These are typical symptoms of worn engine and box mounts, and usually you get the gearstick jumping around along with the thunk, but i've replaced/stiffened the engine and box mounts already, and the stick doesnt move at all, so the issue is elsewhere.

    I suspect its a combination of issues all working together. Lots of little bits of slack, combining together and adding up. I know one of the front inner CV's still has a small amount of play, and i've not checked the rear CV's yet, but i suspect at least one of those has play in it too. It seemed to improve significantly when i fixed the play in the propshaft CV and swapped out the gearbox.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


  9. #8
    jcb
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    if you stiffen one part the load is transfered to the next weakest part for any movement.

    get someone under a ramp while you load the clutch with the handbrake on.

    you will be surprised what and by how much things move!
    I had a dyno done years ago and the bloody engine nearly jumped out of the engine bay it was so slack!

  10. #9
    "Stick a V8 in it!"

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    yeh exactly. Worn engine, gearbox and diff mounts are a good place to start, they're likely to be knackered anyway

    If its still there after you fix those up, then its gonna be play in the driveline somewhere. Both my front CV's had play in them (i had a spare good CV so swapped it out) as did the propshaft. The diff itself has a fair amount of backlash, but my saloon has similar play in the rear diff and doesnt exhibit the same symptoms.

    My next step is to fix the front CV which i know has play, and pull the rear shafts out and inspect them.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
    1997 S4 - PPC £999 Challenge Track Car Build
    TD5 Land Rover Defender build


 

 

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