8.5” BOP rebuild

Discussion in 'Got gears?' started by Darron72Skylark, Oct 13, 2019.

  1. Gary Bohannon

    Gary Bohannon Well-Known Member

    Thanks for that info Brian.
    I have a Truetrac 8.5 with stock axles and 3500 stall TH400 & never have wheel hop.
    60 ft. is 1.60-1.63 range. Will stock axles hold up?
     
  2. BrianTrick

    BrianTrick Brian Trick

    Gary,
    How heavy is the car? I assume that is a foot-brake TH400?
     
  3. Bens99gtp

    Bens99gtp Well-Known Member


    I was running mid to low 1.50s on that axle that was twisted in only 25 passes.
    After seeing that I will not try running much faster than low 1.6s to upper 1.5s on st axles. We are going 1.45-1 43 now and there is no way in hell the stk axles would take this
     
    Gary Bohannon likes this.
  4. BrianTrick

    BrianTrick Brian Trick

    I always say the stock axle are good in a typical automatic A-body,running 11:70’s or slower. Anything like a trans-brake,clutch,slicks etc.,will add more blunt force at home plate,and therefore a slower or less-powerful car could twist them with any or all of those factors.
     
    Gary Bohannon likes this.
  5. Gary Bohannon

    Gary Bohannon Well-Known Member

    Thank you Ben and Brian,
    Exactly the answer I needed.
    Are stronger axles available in 28 spline to fit my truetrac?

    (3700 lbs, foot brake only and 3500 stall, mt drag radials)
     
    Last edited: Oct 16, 2019
  6. BrianTrick

    BrianTrick Brian Trick

    You can get 28-spline Mosers made.
     
  7. Darron72Skylark

    Darron72Skylark Well-Known Member

    Are they any stronger than stock?
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I upgraded my 8.5 to 30 spline Moser axles.

    According to the article I linked, 30 spline Moser axles are good to 6200 ft. lbs.

    upload_2019-10-16_15-52-6.png

    TQ X 1st gear X rear axle ratio? Aren't they leaving out the torque converter?
     

    Attached Files:

    Last edited: Oct 16, 2019
  10. Bens99gtp

    Bens99gtp Well-Known Member

    Seems I have too much for my 30 splines. Lol maybe that explains the issue I had this spring
     
  11. Gary Bohannon

    Gary Bohannon Well-Known Member

    How much does the torque conevrter stall add in on final torque to the axle.
     
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I'd say around a factor of 2, but that is below stall speed. Once a converter couples, torque multiplication ceases. So I'm thinking that a properly set up Race car leaves on the trans brake at full converter stall so converter torque multiplication is minimal. Then again, there is always some slippage, so some torque multiplication. I might be wrong though.:)
     
  13. Bens99gtp

    Bens99gtp Well-Known Member

    Your 350 is well within what 30 sines will handle, my 464 is north of 650 for both hi p and torque. I would be shocked honestly if 28s wouldn't hold up
     
  14. Darron72Skylark

    Darron72Skylark Well-Known Member

    Ben, I took your advice! Brian Trick is helping me out with 30 spline axle shafts, a TrueTrac limited slip, and Timken bearings!
    I'll post pictures of the install once it is all here.
     
  15. Bens99gtp

    Bens99gtp Well-Known Member

    You should have a rock solid rear end setup that should last for many years
     
  16. Darron72Skylark

    Darron72Skylark Well-Known Member

    Lifted the car last night intending to start prepping the axle for paint but instead discovered that there are oil leaks. Looks to me like a slow leak on each side of the pumpkin where the axle tubes press in, and a small one on the cover as well.

    The cover will get replaced with a TA girdle and new gasket, but what should I do about the axle tubes? Should the whole thing come out to weld the tubes to the center section? Are there other ways to deal with this?

    Thankfully, there are no leaks showing around the pinion.

    D5CAA8B6-A7CD-4CA8-A35D-E90C61FCC724.jpeg CB0C2919-71FF-478C-8D03-15102069917C.jpeg A6E31D59-10AE-4B9B-81F6-78F09C65E4B2.jpeg 7543E117-4D44-4DBB-AB3A-8BDEEF1DA732.jpeg 14334B20-6016-4F1A-8A9C-73848ACF31F4.jpeg 10639E45-0C63-4EFC-961A-D9EA3FD74C51.jpeg BB01EC01-0BF6-477A-8DAC-102FF08C93ED.jpeg
     
  17. agetnt9

    agetnt9 Agetnt9 (Dan)

    The oil is not coming from where the tube is pressed into housing but where the hole is welded to keep the axle tube in the center section .
     
  18. Darron72Skylark

    Darron72Skylark Well-Known Member

    Those two dimple-like indentations on each side of the back of the center section you mean? Is that where the tubes are spot welded? Should I put seam sealer or something similar there?
     
  19. monzaz

    monzaz Jim

    CLEAN IT FIRST WITH BRAKE CLEANER ...BLOW DRY... THEN seal it.
     
    Darron72Skylark likes this.
  20. Darron72Skylark

    Darron72Skylark Well-Known Member

    Thank you! I have a half case of brake cleaner for the task! And a tube of seam sealer
     

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