9 3/8" rear differences

Discussion in 'A boatload of fun' started by quicksabre, Apr 22, 2005.

  1. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Not only is it wider,it doesn't have the "ears" on the "pig" that the upper control arms attach to like the A-body does on your '65 GS.

    You may be able to sell the 9 3/8 or parts from it though.GL

  2. sodak65

    sodak65 Well-Known Member

    thats a bummer I guess i should have crawled under the car in the snow to look but its -10 out lol. I was looking at picstures of these rears online and it showed up mounts just like my GS maybe differnt year? what does the Lesabre use for upper mounts then?
  3. obiestar23

    obiestar23 Member

    I got a 1970 buick wildcat convertible and I can't find rear end gears and/or posi. Can anyone help me out here? Trying to finish this before winter comes around. Thanks
  4. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Contact monzaz in the rears and gears section.GL

  5. 74electra225

    74electra225 Member

    Ok I just read this whole thread here is what gathered from it and also what i can add to help.

    Here's what I know from experience.

    The Oldsmobile built 12 bolt 9 3/8" can be only found in 71-75 Buick's and Oldsmobiles. Sedan housings and station wagon housings are different due to the sedan being coil suspension and wagons being leaf.

    Axle shafts are a non c-clip bolt in style with 31 spline. Wagon and sedan are the same length.

    Pinion yokes and driveshafts are different between wagon and sedan but are swappable. Also a GM 8.5 yoke from 71-76 will work.

    Cadillac housings are totally different the upper control arms are a different design and the center section is offset. But the driveshaft yoke and lower control arms are the same.

    There is absolutely no aftermarket support for these rear ends to my knowledge.

    My questions to you guys are..

    is 3:42 the lowest possible gear set for 71-75?

    is 3:42 the lowest gear set for 66-70?

    Any aftermarket support for 66-70 gears?

    What type of mods does a guy need to do to use an older 66-70 gear set in a 71-75 housing? Besides the older seal?

    Does anyone know if a modified 9 3/8 spool will work?

  6. 64 wildcat conv

    64 wildcat conv Silver Level contributor

    Lookin to beg, borrow, or rent two tools needed to help with the posi install on my 64 Wildcat. I need the carrier bearing support puller and the spreader tool (looks like a big c-clip) that allows you to preload the carrier bearings.
  7. 72GSX4ME

    72GSX4ME Speed Racer Wannabe

    To the 9 3/8 rear end experts. Bought this rebuilt posi unit off eBay over 8 years ago. Was told it was for 9 3/8 big car. The carrier says 700 on it. Long story short, found complete posi rear so do not need it. I know someone could use it. Checking item before putting on PARTS FOR SALE on board. Anyone ever see the 700 code?


    image.jpg image.jpg

    Attached Files:

  8. 73Electra 225

    73Electra 225 Well-Known Member

    Is that a Buick 9 3/8"? I might be wrong, but looking at the pics, I want to say there are too many ribs on both sides of carrier for either pre or post '71.
  9. RoadShark

    RoadShark Well-Known Member

    Here's some pics of my '67 for reference:

    Attached Files:

  10. limited_driver

    limited_driver Well-Known Member

    Guys, can anyone identify this posi carrier? Excuse the poor photos: it's on a shelf overhead in a retired mechanic's garage, who brought it home from work in 1973 (if he is recalling correctly). This was installed in a full-size GM car that was new at the time: the lady owner wanted the limited slip removed and it was replaced with an open carrier. He brought the barely-used posi-guts home from work. Again, I'm unsure if this story is exactly correct or true. It is in a GM box with markings too faded out to read.

    After hearing it was out of a full-size car, I was going to buy it for my 1971 Riviera with open rear axle and 2.93 gears, but have since found thanks to monzaz's wonderful and informative posts that not all full-size GM axles were the same during this time. I have read my axle is a Oldsmobile-designed 9 3/8" 12-bolt unit. The photos I've seen posted of what these carriers should look like (including in this very thread), look different from this posi that is available locally.

    Can any one confirm what it is? I also own a '75 Pontiac Grand Ville Brougham 4-door hardtop with a 455, which I believe has the Pontiac 8.875 10 bolt cover, 12-bolt guts rear axle. Maybe it would work for that? If it's just an 8.5 Chevrolet carrier, I think I'll pass.

    Thanks guys!

    -Josh Noiles
    Nova Scotia, Canada

    [​IMG]Untitled by Josh Noiles, on Flickr

    [​IMG]Untitled by Josh Noiles, on Flickr

    [​IMG]Untitled by Josh Noiles, on Flickr

    [​IMG]Untitled by Josh Noiles, on Flickr

    [​IMG]Untitled by Josh Noiles, on Flickr
  11. RoadShark

    RoadShark Well-Known Member

    If you can pull that outer race off the bearing and get a part number off it, you might be able to cross-reference it to the application. Especially if it's a Timken.
  12. Eric Aull

    Eric Aull Member

    Does anyone know which IF any GM rearend HOUSING will directly bolt into a 71 Riviera......I have been told "none"....???!!! Please help, Thank you, Eric
    73Electra 225 likes this.
  13. RoadShark

    RoadShark Well-Known Member

    I don't know for sure, but I would guess that only '71-'73 Riv housings will bolt in. The Riv isn't a GM B-body or C-body, so I don't think any of those will bolt in. I may be able to look at a Hollander book this weekend and confirm, but I doubt you'll find alternates.
  14. RoadShark

    RoadShark Well-Known Member

    I had a chance to look at Hollander in case you are still interested. Hollander number is 114 (231092). More housings interchange than I thought:

    Buick '71-'75 12-bolt cover except S.W. (coil spring)

    Olds '71-'75 12 bolt cover except S.W. (coil spring)

    Riviera '71-'75
  15. flynbuick

    flynbuick Super Moderator Staff Member

    This is a delayed answer:

    For 65 you could get a factory 4.45 rear gear ratio.(There are factory part numbers assigned.)

    For 65 - 70 Buick offered a 3.91 ratio for the 9 3/8" rear. (There are factory part numbers assigned.)

    For 71-75 I see the 3.42 as the highest numerical ratio made for an Olds/Buick 9 3/8". (Someone needs to check the Olds parts books to verify this.)
    Last edited: Mar 27, 2018
  16. flynbuick

    flynbuick Super Moderator Staff Member

    PJ Caruthers likes this.
  17. David Brown

    David Brown Member

    those years bolt right into a 71 rivi???
  18. David Brown

    David Brown Member

    Just picked up a 71 riviera a couple weeks ago. Looking to make it Posi. So I crawled under it today and found a few casting numbers. It’s a 12 bolt. I took some pics while under. Noticed the driveshaft has a double u joint right before the pumpkin. Is this factory or a modification. Can anyone tell me if all looks stock or did it get modified.
    Also what’s the fest way to make it Posi?

    Attached Files:

  19. flynbuick

    flynbuick Super Moderator Staff Member

    Just the 3.42 ratio from a 1971-75 Buick or Olds 9 3/8" rear would fit a 71 Buick Riviera rear. The pre 71 Buick 9 3/8" rear gears will not fit a post 70 Buick 9 3/8" rear end.
  20. David Brown

    David Brown Member

    Sorry, I ment the entire rear axle bolting into the 71 riv from other years. I see on some sites saying a GM that would fit but not sure if they are correct cause it’s my understanding that the 71-73 are different rears any other years.

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