1972 Buick Riviera Rear Axle

Discussion in 'Got gears?' started by Airtight1975, Feb 6, 2017.

  1. Airtight1975

    Airtight1975 New Member

    Hello can anyone tell me if my 72 Riviera has a C-clip or non C-clip rear end and if the axle is configured like the attached diagram? Screen Shot 2017-02-06 at 12.17.25 PM.png
  2. Smartin

    Smartin Stainless Guy Staff Member

    They are bolt in axles but I'm not sure on the bolt pattern off hand
  3. flynbuick

    flynbuick Super Moderator Staff Member

    The rear is a post 1970 (BOP) 9 3/8".
  4. Airtight1975

    Airtight1975 New Member

    Thanks guys
  5. monzaz

    monzaz Jim

    IN 1971-1976 Gm implemented a cubic inch to size rear rule of thumb... Normally if the car had a 455 you got the 9 3/8 Oldsmobile rear if the cars had 400 350 they could get hte 8.875 pontiac reaR. (pONTIAC REAR HAD A 10 BOLT SCALLOPED COVER WITH 12 BOLT RING GEAR AND LARGE 1.875 PINION SHAFT.

    BOTH these rears were Bolt In Axles and both were 31 spline 45 degree cut axle spline angle.

    The older 1965-1970 GM axle spline full size car 31 spline axles were old 60 degree spline more straight up and down looking.

    YOU CAN NOT fit the newer axle spline in the older posi BUT you can fit the older axle spline in the newer 45 degree spline posi / open side gear.

    Just some good useful info for down the road...

    J D RAce
  6. Bigpig455

    Bigpig455 Fastest of the slow....

    Does anyone know what the carrier breaks are for the Pontiac 8.75 rear?
  7. monzaz

    monzaz Jim

    Not super sure but this is how I think it goes... Some with a manual please correct if necessary

    2.28 2.41 2.56 2 series
    2.73 2.93 3.08 3 series
    3.23 3.42 3.73 and beyond 4 series
    this rear has come with 3.90 4.33 ratios also from the factory
    We have had 2 sets of 4.33 ratios in hand at one time in the past. Original GM stuff

    J D

    Attached Files:

    Last edited: Apr 15, 2018
  8. Brent

    Brent Well-Known Member

    Hate to high jack this thread, but I will do it anyway. What are the carrier breaks on a 9 3/8 corporate, also what is a posi unit out of a 9 3/8 worth? Out of a 72 Riv with 2.93 gears. I have the whole rear end but there is a little bit of rust on the pinion, everything else seems excellent.
  9. Boatjouster

    Boatjouster New Member

    What ratio should I use for my 72 ? 3:42 ? just looking for cruising and fun..
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    3.08 would be good, but no one makes gear sets for the 9 3/8" Buick rear. That means you need to find them 2nd hand. That will not be easy.
    Boatjouster likes this.
  11. monzaz

    monzaz Jim

    There is no BUICK rear in 1972.... that is a OLDS 9 3/8" rear...Buick lost all rears in 1970.
    Only Pontiac Olds and GM 8.5 were available. in 1971 for the FULL size cars.
  12. Iceship

    Iceship Member

    You guys know off hand the width from plate to plate.. likely my best bet is to swap rear end out
  13. monzaz

    monzaz Jim

    For what?
  14. Iceship

    Iceship Member

    72 Riviera.. I'm looking in to having a 9in posi rear end cut down.. weighing my options
  15. monzaz

    monzaz Jim

    Might as well just use a 10 bolt 8.5 rear same deal and it bolts right in. 1971-1976 10 bolt 8.5 rear is a direct bolt in from any FULL size GM car. riv Electra Catalina Bonneville 98 88 olds etc. Look for the LOW HP motor cars. 350 2 bbl 400 etc. Centurion Chevys Impala Caprice etc should have the 8.5
  16. Iceship

    Iceship Member

    Ok thanks.
  17. 74electra225

    74electra225 Member

    Hey there .. your Riviera came with the 9 3/8 oldsmobile differental under it .. side note if anyone has 3:42 gears for this style of rear id be interested in them
  18. 74electra225

    74electra225 Member

    You can swap a 10 bolt 8.5 out of any 71-76 fullsize GM sedan car minus Cadillac
  19. Steve Schiebel

    Steve Schiebel Well-Known Member

    Attached is the axle housing tube end flange dimensions. Made drawing when transplanting '76-'78 Seville rear disc setup onto my '71 Riviera years back. axle tube flange.png

    Attached Files:

  20. monzaz

    monzaz Jim

    Humm... Must have remachined the holes then huh... cause 76-78 seville is a small axle tube end the 71 Riv is a full size car flange pattern you have up.

    Here is the Seville measurements.

    Attached Files:

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