Centurion Posi options

Any options for adding a posi and/or a numerically higher gear set for my 72-73 Centurions or should I just 'pass' and run open rear ends?

I have NEVER seen a stock posi in a Centurion/LeSabre BUT have seen several in the Rivieras of the day BUT am told the Rivieras used a different rear axle set up so I am screwed.

 

LeSabre/Centurion used an 8.5 in 350 cars and an 8.88 in 455 cars. Riviera, Electra and Estate wagons used 9.375. I'm sure positraction was an option on the LeSabre and Centurion. I don't know if the larger rearend can be used in your car without modifications.

 

All 71-73 455 cars did not use 9 3/8 or were you thinking later years?

 

My info was from 73

 

Yes 9.3 rear was used in the 70's it was OLDSMOBILES 12 bolt cover and 12 bolt gut rear end FULL size cars used them...They are 31 spline axle rears BOLT IN AXLE. I am working on some retro stuff as we write. I can NOT promise anything at this time but some parts I have dug up look promising. WILL SEE. Jim

I am not as familiar with the riv rear in the 70 71 72 era does anyone have pictures of the cover for that era? Did they use the Buick 10 bolt covered 9.3? I know the 66 67 68 and maybe 69 did...

reference pictures and see which one yours looks like -


from left to right-
8.875 full size (mostly found in pontiac early then later and mid 70's
9.3 buick used 66-69,70 ish
9.3 olds full size used 1966-1975 ish


Jim

 

This is a 3.42 gear 9.375 posi rearend out of a 72 Riviera I think 71-76 Riv's used this.

 

Yep that is a Olds 12 bolt rear center. Uses this posi unit.

DO NOT confuse this with the 12 bolt olds rear from A BODY GM which has 10 bolts on the ring gear THIS olds is a true 12 bolt rear cover and 12 bolt ring gear. Jim

 

Great. I like the cars with the "odd" rear axle size.
ou:

I had heard that Riviera rears did not work and I never understood but there are a lot of differences between Rivieras and full size LeSabres/Centurions BUT it makes me a little upset that Electras seem to have relatively a lot of posis and they are a different size as well.

All were fronted by 455's!

I have owned 6 Centurions and responded to countless Centurion ads and never located a factory posi.

 

Electra and Riviera rearends are the same, the guts won't work in yours, but not sure if a complete rearend swap would work.

 

Send pictures of the rear cover you have under the centurion and will check it out. Jim

 

but not sure if a complete rearend swap would work.



yes, it will.

the best option is to find one of the 8 1/2" rears from a small block 1971-76 B body mentioned earlier and install that. the large car 8 1/2" uses the same gear sets and carriers as the bog standard Chevy 8 1/2" rear. i have installed those in a 1971 and 1974 Electra.



I am not as familiar with the riv rear in the 70 71 72 era does anyone have pictures of the cover for that era?


there should be a split between the 1970 and 1971 designs. the 1971 Riv rear is the same as the 1971 Electra rear.

i think the 1970 has goofy bearing sizes, check out the rear end stickies in the Boat forum.

 

I think 1970 still had the 3 link and one track bar system and in 1971 ALL full size and a-body were 4 link NO track bar. basically all cars were set up like A-body GM. Except the obvious nova and camaro leaf spring rears. Jim