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front diff mount

Discussion in 'Gearboxes and drivetrain' started by cooper1203, Aug 8, 2018.

  1. cooper1203

    cooper1203 Member

    Bit of a long winded one. I am confused as to how the front rubber diff mount is attached to the crossmember on a 3500s 1973. I basically have an oval flange with a bit of rubber through the middle of it. thin bit of rubber sticking out one side and thick bit sticking out the other. when it was on the car the flange was on top of the crossmember with the thick bit of rubber sticking up towards the bottom of the car. both the parts book and the workshop manual show it thick side pointing towards the ground but more importantly mounted on the underside of the top of the cross member if that makes any sense.

    Issue I have with this is that would mean the only thing holding the diff in place is 2 5/16 bolts yet they have a great long 7/16 hardened bolt to hold the mounting together

    which is the right way please
    many thanks
    coop
     
  2. harveyp6

    harveyp6 Well-Known Member

    http://www.rover-classics.co.uk/images/reference/thumbnailv8/final drive/gallery/images/Extension Case & Propellor Shaft_jpg.jpg

    As far as I remember it the way it's shown in the above images is the way it goes. You could mount the mounting on the top of the crossmember but it will still only be held by the two 5/16" UNF nuts and bolts.
    On the 2000 those 2 nuts and bolts would pull through the crossmember and the mounting would drop downwards, so it must have been mounted under the crossmember for that to happen
     
    Last edited: Aug 8, 2018
  3. quattro

    quattro Well-Known Member

    The front of the diff isn't that heavy so the 2 x high tensile bolts hold it easily.

    When you put your foot down a bit hard, the front of the diff is forced upwards with some force, hence the reason the front mount looks to be upside down. It isn't there to hold the weight of the front of the diff, but to take the upward force.
     
    PeterZRH likes this.
  4. cooper1203

    cooper1203 Member

    that's the image I was looking at. wm says something similar just doesn't make sense to me that they have all that weight and torque on a couple of 5/16 bolts especially when the three on the back are specially coned and 7/16,

    ps are you the Harvey in the roc mag under the technical advice section?
     
  5. cooper1203

    cooper1203 Member

    quattro what holds the weight then??
     
  6. harveyp6

    harveyp6 Well-Known Member

    Yep.
     
  7. harveyp6

    harveyp6 Well-Known Member

    The mounting centre tube, the rubber insulates it from the outer plate that's bolted to the crossmember.
     
  8. cooper1203

    cooper1203 Member

    ok thanks ill leave it like the pic says then.
     
  9. quattro

    quattro Well-Known Member

    The main weight of the diff is held by the rear mounts, with 2 x 7/16 high tensile bolts hanging on two rubber mounts the same as the singular front one, but the other way up. The diff isn't that heavy, I can carry it around reasonably easily (unlike the jag one I'm fitting :eek: ), and the large HT bolts and rubber mounts are there mainly to stop it twisting itself out when driving. Not only does the front lift under acceleration, but it tries to twist around in the same direction as the propshaft as well.

    Richard
     

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