Olds 12 bolt??

[DennyPett]

Ok, as it turns out, I'm thinking the 12 bolt I slapped in my Bu is an Olds setup based on the smooth diff cover. Which really wasnt much of a concern to me since I am gonna run a spool anyway and was only looking to use the housing. However, I've learned that the Pinion bearing on the olds is actually smaller than on the chevrolet 12 bolt, if that is in fact the case, my pinion options are limited dur to the different bearing size. What I'm wondering is, I'm assuiming the diff housing itself is the same, there for, I SHOULD be able to buy the Chevrolet pinion bearing and run the standard 1.625 pinion? am I correct in my assumptions? The pinion seal for both Chev and Olds 12 bolts are the same, so I'm thinking just going with the other bearing would solve any issues. Any feed back would be appreciated as the rear is my focus right now, doing one section of the car at a time!

Thanks,
Denny

 

[bowtie81]

This may help ya buddy
http://maliburacing.com/forum/viewtopic.php?f=2&t=88961

 

[DennyPett]

Well, I know its an Olds rear...lol. But didnt help with the bearing question... LOL

 

[sbmalibu]

I doubt the bearing is the same also you can NOT use a 12 bolt ring and pinion or spool in this rear its a hibrid of a 10 and 12 bolt and very hard to find parts for.Also its mostly 8.2 in internals but with no c clips and i dont believe you can use a ring and pinion for those either.

 

[DennyPett]

I doubt the bearing is the same also you can NOT use a 12 bolt ring and pinion or spool in this rear its a hibrid of a 10 and 12 bolt and very hard to find parts for.Also its mostly 8.2 in internals but with no c clips and i dont believe you can use a ring and pinion for those either.

Mother Effer.... Thats what I was affraid of... I looked at the pinion bearings at Oreilly tonight for both... completely diff... basicly I have a 12 bolt boat anchor... FFFFF curse_sign.gif

 

[sbmalibu]

If it has a posi and decent gear in it you can use it.Ive seen one live behind alot more power than it was supposed to.69 chevelle 454 turbo 400 2800 stall on street tires its still working,i just remember we couldnt find gears for it at the time.You might try randys ring and pinion i think he may have some stuff for these now.Just a thought.

 

[DennyPett]

If it has a posi and decent gear in it you can use it.Ive seen one live behind alot more power than it was supposed to.69 chevelle 454 turbo 400 2800 stall on street tires its still working,i just remember we couldnt find gears for it at the time.You might try randys ring and pinion i think he may have some stuff for these now.Just a thought.

Its an open end 3.08.. I'm gonna pull the cover and make sure, just looked at dudes ad again that I bought it from and it clearly states its out of a 72 Chevelle... I can also look at the housing by the pinion area, found pics of both rears and there is a design diff, so I'll keep my fingers crossed...

 

[sbmalibu]

Iirc 70 was the last official year for the car 12 bolt some select early 71 chevelles got 12 bolts and after that they converted to 8.5 10 bolts from the previous 8.2 design.

 

[monzaz]

Just remember that all factory 12 bolt chevy rears are c-clip axle retention

All 12 bolt oldsmobile ('O' Type) rears are factory bolt in axles.

Some of the early 67-68 olds 12 bolts came with 31 spline axles... There is nothing wrong with the rear and has bolt in axles which is great. The do make 3.42 and 3.91 gears (the gears are about 280-300 though...ouch. Bearings are all available the pinion has a 12 bolt inner bearing and a 10 bolt 8.2 outer bearing and uses the Pontiac 8.2 10 bolt yoke.

We can retro fit a 8.5 power trax unit into an open carrier to do the job with the posi unit.

Hope this info helps. IF you need more help just PM me you can call and we can discuss all you options if you do want to build it up. Jim