Rear end clunk still happening after replacing subframe bushings and diff mount

  • #1

    Rear end clunk still happening after replacing subframe bushings and diff mount

    Hey all, im stumped on this one. I was getting the common rear end clunk and hesitation when i shift or start moving in first gear. I replaced my subframe bushings and diff mount with polyurethane ones and im still getting the noise and loose feeling. At this point ive replaces my motor mounts and trans mounts with poly as well so the only non poly part is those 2 large bushing on the trans mount bracket which i dont understand how that could be the issue. Ive check to make sure everything is tight in the rear. Im starting to think its a lose axle or drive shaft or something. Does anyone have any idea what it could be? Its incredibly annoying seeing as i have to constantly baby the clutch to keep from getting somewhat violent jerking. Thanks in advance
  • #2
    Maybe you have a bad u-joint in your driveshaft. BTW, which poly engine mounts did you get?
  • #3
    Check the upper and lower rear spring insulators, also. Right rear rubbers turn to mush after a few decades of being torqued.
    Been there, done that.
  • #4
    If it happens only when you get on the gas or off the gas, it's either rear subframe bushings or trans mount
  • #5
    I have a worn side bearing in my diff. The axle makes a distinct clunk if I'm not easy on the clutch. The axle stub in the diff moves up and down a good bit by hand.

    Check your U-joints and double check that everything is tight/installed correctly. If you're feeling brave, get the car up on four stands (a lift would be preferred). Set the hand brake and have someone go from reverse to first a few times while you look/listen for the clunk.
    5.3 LSx Z31
  • #6
    I have the same problem ever since my wreck last year and the shop that "repaired " it. Reverse clunks the worst unless you baby the clutch. I do have a whining at certain speeds and all gears will clunk if you don't ease out the clutch engagement. Mine is most likely the drivers side axle stub since that's what was replaced.
    Everything is Meaningless.
  • #7
    Well, It is much more noticeable above 35. but at all speeds really. just at low speeds its usually too low to notice. been down that road twice lol..

    Project Black Betty
  • #8
    PulseCode;n766048 wrote: I have the same problem ever since my wreck last year and the shop that "repaired " it. Reverse clunks the worst unless you baby the clutch. I do have a whining at certain speeds and all gears will clunk if you don't ease out the clutch engagement. Mine is most likely the drivers side axle stub since that's what was replaced.
    If you suspect the axle stub, I would undo the bolts attaching the axle, get under there with a giant breaker bar (30mm socket) and give that prevailing torque nut a good tightening yank… could be loose, and it's supposed to be close to 200ft-lbs tight

    Also a possibility is that C-clip holding the diff and axle together came apart, and your axle is able to move out of the carrier to wobble… you can check that with a crowbar, prying the two apart
  • #9
    Hmmm, my rear end whines and vibrates =[
    __________________________________________________ ___________________
    "Aim towards the Enemy." --     Instruction printed on US Rocket Launcher

    86 N/A:Rebuilt Autotragic, Cat Delete, PRW-2, Poly Bushings, MSA sway bars, Pioneer HU and Speakers, Sleepy Eyes
    Current 0-60: 10.0 flat =[
  • #10
    Try the side diff bearings then inside rear wheel bearings (after confirming proper alignment and good tires. Remember at least 50-70 percent of road noise comes from tires). The wheel bearings can cause crazy nasty issues when bad. (i have vids to prove it)

    Project Black Betty
  • #11
    Yeah this'll sound stupid of me, but my rear camber has been fucked for months because when I did the control arm bushings, I didn't have ramps or a lift to do final tightening on all the bolts at curb weight of the car, so my camber doesn't stay lined up and at times, moves on it's own. But I'm quite literally getting a free set of ramps today, so that won't happen again.
    __________________________________________________ ___________________
    "Aim towards the Enemy." --     Instruction printed on US Rocket Launcher

    86 N/A:Rebuilt Autotragic, Cat Delete, PRW-2, Poly Bushings, MSA sway bars, Pioneer HU and Speakers, Sleepy Eyes
    Current 0-60: 10.0 flat =[
  • #12
    Camber cannot be adjusted without modification of some form. Do you mean toe? Anyways, get a proper 4 wheel alignment and they will tighten everything proper for ya while doing it.. Toe will cause more noise than camber btw..

    Project Black Betty
  • #13
    Check Drive shaft carefully for play, while the car is on a lift or jack stands is also a great time to check the diff input shafts and fully seated, if those circlips have not bee fully rammed in they will thunk around and make noises.

    Its also worth putting new boots and re greasing the CV joins in the half shafts.

    The old rear end clunk always ends up being a real combination approach, DON'T assume anything and check all of the items in this entire thread.

    I once stripped a diff down chasing bearing noise because i was certain my wheel bearings were perfect ( as they were replaced) and oh how wrong was I.

    Moral of the story check everything that moves, you have a really good start so keep at it and you find find the offending component soon.
    85 Turbo Slick Top
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