Will this rear end fit my 79 ?

Discussion in 'Transmission & Driveline Topics' started by barri corps, Apr 24, 2012.

  1. barri corps

    barri corps Member

    Nov 26, 2010
    ipswich, united kingdom
    Hi guys.
    Will a 10 bolt rear end from a 1972 trans am install straight onto my 1979 z28 without modification ?
  2. Musmoke

    Musmoke Veteran Member

    Oct 9, 2006
    Kingston, Ontario
  3. fbody_mike

    fbody_mike Veteran Member

    A few potential issues:

    1. The yoke may be the wrong size. The stock yoke on the early 2nd gen rear ends is smaller than the later ones. There is a conversion U joint to solve this problem.

    2. Brake lines. The flex line setup might be different. The early 2nd gens had the Tee end of the flex line mounted to the diff cover. The 79 will have a bracket for the flex line on the driver side axle tube. Easiest solution may be to fabricate a bracket to hold the line to the axle tube of the 72 differential.

    3. The gear ratio may be different, requiring a speedo gear change. This is true of any rear end change.
    Last edited: Apr 24, 2012
  4. barri corps

    barri corps Member

    Nov 26, 2010
    ipswich, united kingdom
    Thanks for your fast responses.

    The yoke shouldnt be a problem as i am taking off an existing rear end and im assuming if needed i can reuse the one i have already?

    The ratios will be different, that is the reason im doing the swap, at present i have richmond 4.11 gears in the rear which i absolutley hate as i do a lot of motorway driving, i am installing a fully reconditioned rear from a 72 trans am with 2.73 gears.

    I will sort out the speedo when im done.

    I did have another question, will there be a noticeable reduction in acceleration with my new rear because at present it launches like a saturn rocket!, am i set to be dissapointed or will it be not to different ?
  5. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    The car will launch much softer with the change from 4.10 to 2.73, but highway driving will become fun.
  6. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

    Sep 20, 2004
    Southern Maryland
    Changing yokes will disturb pinion bearing preload unless you are extremely careful. I would much sooner use a conversion u joint than take a yoke of a rear that you don't plan on internally rebuilding.
  7. barri corps

    barri corps Member

    Nov 26, 2010
    ipswich, united kingdom
    where would i find one of these adaptors if needed

    Anyone have a link ?
  8. big gear head

    big gear head Veteran Member

    Jul 30, 2001
    Central City, Ky.
    If the rear end was reconditioned then I'm assuming that this means it was rebuilt with new bearings. If you want the yoke changed then take your rear end to the person who rebuilt the Trans Am rear end and have them change it. That way they can set the pinion bearing preload correctly and you won't have any problems with it. If you try changing the yoke then you will probably mess up the bearing preload and cause a rear end failure. It shouldn't be hard to find a 2.73 gear in something else. You could have the gears changed in your rear end and the brake lines and yoke will be correct.

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