1971 - 9 3/8 inch posi project

Discussion in 'Got gears?' started by Patsusedparts, Mar 2, 2020.

  1. Patsusedparts

    Patsusedparts Well-Known Member

    Hi all; After a long pause I am back on the 1971 Riv restoration. This weekend I was doing rear axle work. I had spent a ton of time researching on this board and others and in particular this thread -


    which has been a wealth of info. I have encountered a few interesting issues and although I think I know what I am going to do, I still wanted to post my story to see if there are any comments or tips from folks that are familiar with the 71 and later 9 3/8' rear. And moreover, perhaps something here will help somebody else in the future.

    My car is a 71 Riviera, and it has the standard (open) axle at 2.93:1. (stamped ID QI 0008). Years back (pre-2010) I scored a posi (3.42:1) which I believe came out of a 71 or 72 Riviera GS (stamped ID QA 0006) it has the "S" shaped preload spring. And I purchased an axle rebuild kit from Ratech. RA-323 which has a pick list titled GM 8.75 rear (photo). But I'll get back to that shortly. So I have pulled out all this stuff out of storage, and this weekend I set to work. My idea was to remove both carriers and transfer the 2.93 ring gear to the posi carrier and put that back into the original rear housing. Thinking I would have a posi with 2.93, which was an option in 1971 (the idea being to be better for highway use, than 3.42). Well it turns out that that is not possible with my parts. Unless I am mistaken on something (like what I really have in this posi unit) always a possibility, it seems that the posi carrier has a unique ring gear mounting flange height such that my 2.93 ring/pinion set will not work on it. Photo shows the 2 carriers side by side. I knew that the 70 and earlier carriers had several changes, but it never occurred to me that the posi carrier wouldn't be able to run any ring gear from the correct years. But I looked at the chassis manual and I noticed that the ID stamp for a 2.93 with Posi option would be QJ. So I am guessing that the carrier in a QJ is different than the QA. And that the QJ carrier would allow for the use of the 2.93 gears. Perhaps QJ is the type with the 3 coil springs for preload? But it doesn't matter now, I have what I have and from what I read, finding anything else will be close to impossible.

    OK, so I don't have the option of keeping my 2.93 gear set if I want the posi, which I do. No big deal, so my new plan is to just rebuild the posi completely (using the kit I have) and put that in the car. I can't recall exactly how I came to purchase the Ratech kit I have, but I think there was something in the Riview years ago that listed all the control arm bushing and bearings/seals/shims. In any case, even though the kit's paperwork says 8.75" GM it seems to contain much of what I need. In fact, I matched up the carrier bearings by number, the outer pinion bearing, pinion seal, and shims and everything matches and/or fits the posi unit except the inner pinion bearing and race. I have not removed the pinion from the open diff, but since the cases appear identical, I am guessing that it also uses the same bearing on its inner pinion that the posi does. And the one in the kit is clearly not it. So I figured - easy, just knock out the inner pinion race, and read the number. Well I knocked it out, all it says on the race is 'Made in USA'.

    Nice, the only thing in the unit that has no number stamped on it is the one thing I need to buy! So I measured as well as I could and did a bit of research and I am pretty sure the inner pinion bearing I need is M804049 bearing and M804010 race. If someone who knows these things (monzaz, Lore, Smartin ?) can confirm that bearing choice; I'd be very grateful. The OD on the race appears to be exactly 3.500" and height of the race alone is .750.

    So now onto the "stupid question" segment. I have not done one of these before. I have bearing splitters, a variety of pullers and a 30 ton press. I have seen some Youtube videos where they heat up the pinion and carrier bearings with a torch to make them easier to remove. Is heat really needed if I have the press? I am starting to suspect that heating might be the approach needed only in cases where you are using a cheap puller and no press. And I certainly don't think I should be heating up up the new bearings.

    Another thing I was planning on doing was putting the axles from my original open diff into the posi, because the bearing and seals on those were done shortly before I stopped driving it. I haven't measured them to make sure, but both are 31 splines so I assume that will be no issue.

    Also, I am not sure how much I will need to shim the carrier, since I am putting the same carrier and gears back in the same housing. Currently there is one "shim" (more like a ring) on each side of both of my axles. They appear original. The have a chamfered edge (to help get the carrier in easier??) and have hash marks notched in them as well as some yellow or white paint marks. I have measured the 4 I have and have guessed that the notches decode as follows.
    3 notches - .235 thick
    4 notches - .245 thick
    5 notches - .255 thick.

    I have the shim kit from Ratech. The outside diameter of those shims is that same as the current factory rings although the inside hole is smaller. That is the ID opening of the shim is smaller than the axle tube ID. I am assuming that will not be any issue, since the ID is still plenty larger than the axle itself. That is if I even have to add any shims. We'll see when I get get up to setting backlash and pre-load eventually.

    Other data, in the event it saves someone from having to ask questions about attributes I didn't mention so far. The car will have the original 455 mostly stock motor (.030 over) probably making about 300 HP. Stock wheels and tires. I did box the control arms, mostly so I can say I did it. No track use, just cruising at highway speeds and going to car shows. The Riv has the flange type (not a yoke) driveshaft mount. Of the 2 seals included with the Ratech kit the 2043 is the one that fits my housing. I assume that the threadlocker and gasket maker in the kit is too old to use. I'll replace those when the time comes. The kit includes a new crush sleeve as well as a new pinion nut. But the new nut, although the threads are correct, is far less substantial than the old one. So I am planning on reusing the original. My guess is that the nut they sent is sized to fit inside a U-joint yoke, but the Riv uses a flange driveshaft.

    IMG_4060.JPG IMG_4069.JPG IMG_4062.JPG IMG_4061.JPG

    thanks for reading this far!

    Attached Files:

  2. monzaz

    monzaz Jim

    Ready- :)

    Part Number

    Carrier Bearing


    Carrier Bearing (Race)


    Inner Pinion Bearing


    Inner Pinion Bearing (Race)


    Outer Pinion Bearing


    Outer Pinion Bearing (Race)


    Pinion Seal


    You bought a 10 bolt cover 1978 - 1985 12 bolt ring 8.75" kit. This is the smaller pinion than the 8.875 10 bolt cover pontiac with 12 bolt ring. YOU need a 9.3 Olds rebuild kit my friend.
    Your inner pinion bearing and race will not fit the rear you have. I think everything else will except for the crappy small pinion nut ...IT IS wrong and is for a 8.2 or 12 bolt Chevy pinion.
    Boy that kit is screwed up even for the 8.875 an d the 8.75... Again the reason I am so busy...lol.

    Can not see the crush sleeve they likely sent a 8.5 GM sleeve for that as it is a 8.5 pinion in the 8.75 rear.

    On a crush sleeve you just have to make sure your diameter is correct and enough higher than the original crush sleeve you have in the 9.3 1/8" to 1/16' should crush enough.
    Just there for preload and nut torque.

    No cover gasket? I think I still have a few 12 bolt olds 12 bolt cover full size gaskets laying around here somewhere....lol. Jim
    JD Race
    Last edited: Mar 3, 2020
  3. monzaz

    monzaz Jim

    This is what your working on? Yes?

    Full size car rear from 1971-1976 88, 98, riv, Electra, Grandville all with 455 cube motors got this rear.

    Attached Files:

  4. monzaz

    monzaz Jim

    Doughnut hole in shims will not matter.
    your pinion shims in this kit are too small diameter too... :(

    Removal of bearing...You can do what ever you want to remove the bearing as long as it does not hurt the carrier hub ends etc and the pinion shaft etc.
    I would not use torches on NEW bearings!!!
    I have heard people using an oven and freezing the pinion etc....??/ If you have that time... LOL. :D Same with the carrier...You have to work fast!!!! I would assume? Never did this.

  5. Patsusedparts

    Patsusedparts Well-Known Member

    Thanks Jim! Yes I am working on a 1971 9 3/8 from a Riv with 455. 12 bolts on the cover and 12 on the ring gear.

    I ordered the inner bearing and race today. Crush sleeve should be fine, it fits over the pinion correctly, same ID as the one that was in there. And it is about .31" taller.
    No cover gasket was in the kit - they send a tube of gasket maker, if you have a cover gasket, I'd love to buy it, if not I have a roll of gasket material, xacto knife and leather punches. ;)
    The pinion gear has a painted "50" on it (photo). I am assuming that is the size of the depth shim I will find when I remove the inner bearing. I'll put that back and assemble without the crush sleeve to see how the pattern looks. If I have an issue I'll likely post here and figure out what to do then. I have some shim stock around as well. I feel pretty good about getting it done once I have that last bearing in hand.

  6. monzaz

    monzaz Jim

    50 NO THAT IS JUST A NUMBER TO MATCH THE RING GEAR...CHECK THE RING IT MAY HAVE THE SAM,E 50 that is just to match up the gears so they can be a known pair .
    you will see even newer 7.5 8.5 gears will have number and letter combos with marker paint pens and most all of the time the ring has the same matching code letter number

    If you are not changing the ratio and reusing this just use the original shim and do not over think it. :) Jim
    do get that backlash back to .007 - .010 is a good spot for used gears. run the pattern just to be sure and go by your feel of the gear spinning... it will feel good and smooth forward and backward with little effort and noise. a little oil on the teeth will move that compound for the pattern to come in clearer.

  7. monzaz

    monzaz Jim

    it is amazing the paint marks stay on that long after years of driving and oil running over them etc... probably has stuff in it that will kill a normal MAN. :D lol
  8. Patsusedparts

    Patsusedparts Well-Known Member

    I am also amazed at the paint on the side shims. Looks like it was just applied yesterday.
    Regarding the pinion depth; I see I didn't write a great sentence there. But I absolutely planned to put the exact same shims back when I put the new bearings in. As you say; I am using the same case with the same gears, and carrier.

    Thanks again, let me know if you happen to run across a cover gasket.
    I am learning all the time. This is great to have knowledgeable support when I need it !

  9. monzaz

    monzaz Jim

    geex caps AGaIN
  10. monzaz

    monzaz Jim

    Cover gasket is a BUST... I opened the box...It was so old it literally fell apart. :( That was the last one I had.
  11. Patsusedparts

    Patsusedparts Well-Known Member

    Some days I feel the same! :oops: Thanks for checking

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