Rear Axle Help

Discussion in 'Got gears?' started by JStov, May 3, 2020.

  1. JStov

    JStov Well-Known Member

    Looking for a little help. Wanting to change to posi traction in my stock rear end 77 Buick Regal, any direction or advice I’d greatly appreciate. Thanks
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    First, you need to ID your rear. It should be an 8.5 10 bolt.

    http://www.jdrace.com/content/diff_id/10b85.php


    Take a picture of the rear cover/center section from the rear of the car. It should look like this,
    8.5axle3.jpg
    Should have the 2 squared off protrusions (arrows)

    Then the rear U-joint retention to the yoke. Should be 2 straps secured with 4 cap screws. Like this, UjointStraps.jpg
    If so, that is an 8.5 10 bolt. Good sturdy rear with lots of aftermarket support. Posi depends on whether you want to upgrade your axles or stick with the stock 28 spline axles. If you aren't racing, the stock axles are fine.

    https://www.summitracing.com/parts/etn-19557-010
     
  3. JStov

    JStov Well-Known Member

    Sorry for the long response I didn’t even know that I had a response to my question, but from the looks of it yes it’s what you said, a 8.5 10 bolt. Yes I want to go the least expensive route and just beef up the rear a bit to hold on to my new 5.3 motor. I don’t race but the 2.41 rear end I just want to beef up and spin the tires every now and then so sticking with the stock 28 slime should be fine, the car had 60k when I purchased it and was kept up pretty well so I don’t think the rear end should have any worn out parts
     
  4. JStov

    JStov Well-Known Member

    Hey Larry, I didn’t the old spin the tire and mark and count the driveshaft and I came up with 2.41 gear ratio. So will this Easton posi trac fit my gear ratio or will I need to beef the gears up as well????
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    No it won't, you'll need to upgrade to at least 2.73. I'd go 3.08 if you are concerned about RPM on the highway.
     
  6. JStov

    JStov Well-Known Member

    Yes that’s what I was thinking too, is that the highest I can go? wondering if I can go 3.42 or 3.73 without a lot of changing things
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Yes, you can go higher.
     
  8. JStov

    JStov Well-Known Member

    V
     
  9. JStov

    JStov Well-Known Member

    Thank you!!
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    You're Welcome!
     

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