Finding a 10 bolt 8.5 posi In salvage yards

Boy I am, surprise people have not jumped all over that line about holes..... !! LOL.

 

Whats the bolt size for the 4 bolts for the bolt in axles?

 

You want the actual bolt size or the socket size to remove the them?
9/16" socket hex
3/8" bolts

 

Actual

Actual bolt size, thank you!

 

Okay guys so I finally got the diff open and look what I find. S clip posi, no c clips, just bolt it style. I was all set and ready to take the axles out with the open rear end and c clips and I open it up and man was I surprised! But I'm happy!

What fluid should I use with my posi?

 

Pretty sure we IDed this rear already as a 10 bolt 8.5 Oldsmobile ... Bolt in axle rear.
So as we always say BEST to open up the rear end ALWAYS to see what you have.
That is a 725 or 726 casting Posi unit original to the BOLT IN AXLE 71 72 and even into the 73 74 75 76 era BOP 8.5 rears.
So what ratio is the rear now that you have it open? Spin and wipe the OD edge of the ring gear till you find stamped in numbers.

Jim

 

I ran out of time tonight but i will find the gear ratio tomorrow.

 

Sounds like the POSI might need some reshimming or clutches if you did mnot know it was posi from a tire spin test...??? Yes/No? Jim

Why did you think you did not have POSI?

 

I would get it on the lift and spin the tires and the wheels would spin in opposite directions and I was told its not a posi because of that.

I think youre right about shimming or replacing the clutches.

 

9 times out of 10,the clutches are fine,and just need shimmed tighter. They were not set up aggressive at all from the factory.
When you spun the tires,did you have it in park,or neutral?

 

I tried it several times on different days and I believe I've tried in both park and neutral.

 

The left side had 1 shim and the right side had 1 shim or none. I'm gonna investigate more tonight.

 

Are you referring to the shims between the posi bearing,and the rearend housing,or the shims inside the posi unit itself?
When I talk about shimming the unit tighter,I am referring to the shims inside the posi unit itself.

 

Hey Christopher, check craiglist s. florida and space coast--saw an 8.5 Abody rear for sale.

also. check article in buickpreformanceclub.com on 8.2 and 8.5 rears

 

I'm referring to the shim between the friction plates.

 

Thanks Hector, but now that I know I have a posi I don't need a rear end.

 

Just wanted to make sure. I wasn’t sure if you actually disassembled the posi unit yet. Mic the shims on each side,and keep them to their respective sides where they came from.