U Joints | The Z Club of Great Britain
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U Joints

Discussion in 'Drivetrain' started by Makesy, Jun 6, 2020.

  1. Makesy

    Z Club Member

    I suspect my U joints are shot.

    I can feel some play at my half shafts, also when kicking the power in whilst coasting, I can hear a very audible "thunk" noise.

    There's a plethora of options on rock auto...GMB seem to be the go-tos, though there's at least three different GMB options.

    I'm tempted to use the "heavy duty" ones ending in 27, as presumably I can regrease them as needed, though welcome any advice

    1)Have any of you used these?

    2) I'm presuming I need 4 to complete the job?

    3) is it worth doing the driveshaft/diff ones at the same time? (Presume I need 2 of these?)



    Thanks in advance,

    A very lost Alex
  2. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    The 'thunk' maybe the diff nose rising - is it strapped down?
  3. franky

    franky Well-Known Forum User

    I've a brand new set if you want them? 4 in total.
  4. Makesy

    Z Club Member

    Hi Rob, how do I test for this? Jack the car up and wobble the diff?
  5. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    First of all has it got a good strap going over the diff at the front?
  6. AliK

    Z Club Member
    Staff Member Moderator

    I get it when I come off the power - that’s because my diff insulator is shot and the diff is rising on acceleration and dropping down hard as you come off the power.

    Wha I did was to simply jack up the car, get under it with a crow bar and lift the diff. If it’s easy then the insulator is done. There are tolerance quoted in the FSM but a good eye will soon tell if it’s had better days. Mine has connected with the ARB a couple of times in the past!!
    Makesy likes this.
  7. Makesy

    Z Club Member

    Thanks guys,

    I'm going to hazard a guess that it needs replacing, as most "wear parts" on the far are past their best

    I can see straps are available on MSA, but is there a more local/homebrew solution? :)
  8. AliK

    Z Club Member
    Staff Member Moderator

    Well, I remain totally unconvinced by a bit of rubber stopping all that force adequately. Once I can put the front of my car down and raise the rear, I plan to make something left field that I’ve had in mind for some time now.

    The RT mount is the clear winning solution to this issue.

    What I was planning to do - if you can picture it - is to bend strip steel over the diff and down to the tie down points either side where it connects using some Audi ARB bushes I never used on the old car. Then I have a bush to sit on top of the diff bolted to the steel strap. If you beat me to it, I want the royalties
    Last edited: Jun 7, 2020
    Makesy likes this.
  9. jonbills

    ZClub Administrator
    Staff Member Moderator

    AliK likes this.
  10. 240L31

    240L31 Active Forum User

    I think there is much wrong info around regarding the function of the diff strap. With a new, working front rubber mount there should be close to zero upwards movement of the diff nose (<2-3mm). The rubber strap wasn't tight from factory. I think its only task is to serve as emergency strap in case the rubber mount fails.

    Easy check: "clamp" down the diff nose with a thin string and go for a drive. If it isn't broken afterwards, the diff mount is not your issue.

    The 240z strap has "537" embossed which happens to be pretty exactly the circumfence which I measured. You can get timing belts with this exact dimensions (537mm x 40 mm) and use these as replacement for the old leather-like belt. They are fiberglass reinforced and allow zero flex.

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