Strong Pontiac rear axle?

by Spang Sun Nov 17, 2013 10:34 am

Does somebody know anything about 10 bolt Pontiac rear-axles?
They seems pretty strong using 31 splines driveshafts, a 12-bolt ring gear and 11” brakes.
But c-clips are not so good.
Is this a axle to “use as it is, but do not spend more money on it than necessary”.
Do they share parts with other axles?
Is there performance parts avaivable? Gears, posi, c-clip eliminators.

by JB2wheeler Sun Nov 17, 2013 11:35 am

My 74 El Camino came from the factory with a BOP rear end and I am running approx. 540 HP. I have the Moser axles in mine and so far have had no trouble with it (except for the people who installed the posi with used parts when new were supposed to be used). As for reliability, the Chevy and BOP rears are virtually identical except for the C-clips. I often wonder why GM bothered with C-clips. JB

by Spang Tue Nov 19, 2013 6:57 pm

I have found some more information on this axle.
It is sometimes called a 12 bolt 8,75” corporate axle.
It has a 10 bolt cover and 12 bolt 8,875” ring gear.
Axle shaft diameter is 1.40” and has 31 or 28 splines.
Pinion diameter is 1,625”.
All bearings seems to be the same as 12 bolt Chevy.
It was used as a HP-upgrade on 73-77 A-body and Fullsize models.

This 12 bolt corporate rearend seems to be almost as strong as an older Chevy 12 bolt rearend.
But there are no gears available, making it useless for racing use.

JB, is it one of these 12 bolt corporate axles you have?
Moser 31 splines bolt in driveshafts and stock wheel bearings?
Gear?
I am sure it will live a long life in your car, even if you would abuse it using soft slicks and drag launches at times.

by JB2wheeler Tue Nov 19, 2013 7:30 pm

Your descriptuion fits pretty good, but I have never heard it referred to as a 12 bolt anything. The only REAL differance between the Chevy and the BOP (Buick, Oldsmobile, Pontiac) is the method of holding in the axle. I have only once took off full throttle from a dead stop since I swapped engines. I originally had a 400 sb, which was no slough. JB

by Spang Sat Nov 23, 2013 9:26 am

My Pontiac rearend have c-clips.
It is a Pontiac, XCP071D5 is the number.
XC = 3.08:1 Positraction (Disc clutches)
P = Pontiac

I also have another rearend, c-clips on this too.
WCP154D5
WC = 3.08 non positraction
P = Pontiac

On my google-search I have not found any of these weird 12+10 bolt rearends with c-clips.
I think all 12+10 bolts where c-clips.

by dynchel Sat Nov 30, 2013 12:03 pm

photo photobucket-23023-1351170158139_zpsa6f45bd3.jpg

Posi unit photo photobucket-21128-1351170130421_zpse5b4528a.jpg

This might be for that rearend. I bought it on eBay, suppost to be from a '78 camaro, but the numbers don't match anything i can find for a camaro. my research says its for a pontiac rearend.

by w451973 Sun Dec 22, 2013 6:13 pm

Spang - The Pontiac rear end you have is a HEAVY DUTY upgrade from the 8.5 ten bolt. Is is not meant to be a h/d rear for racing. Like you have found out already, there are no gears or performance axles available for these. Your best bet is to find a 8.5 ten bolt with bolt in axles. What is this rear end in ?

JB - This is not the BOP axle you are thing of. You must have a 8.5 ten bolt with bolt in axles. This 9s totally a different animal all together.

DYNCHEL - How many ring gear holes are there on that carrior ?

by dynchel Sun Dec 22, 2013 6:30 pm

w451973 wrote:Spang - The Pontiac rear end you have is a HEAVY DUTY upgrade from the 8.5 ten bolt. Is is not meant to be a h/d rear for racing. Like you have found out already, there are no gears or performance axles available for these. Your best bet is to find a 8.5 ten bolt with bolt in axles. What is this rear end in ?

JB - This is not the BOP axle you are thing of. You must have a 8.5 ten bolt with bolt in axles. This 9s totally a different animal all together.

DYNCHEL - How many ring gear holes are there on that carrior ?

Its at my work, I'll look tomorrow and let you know. santa

by Spang Mon Dec 23, 2013 9:41 am

I have two of these rearends. One is in my Malibu –76 and have 3.08:1 limited slip diff. The other one is 3.08:1 non posi, and I had it on my Malibu –76 earlier.

Let´s say we put a 400 horsepower bigblock in front of this axle and drive around on the streets.
In comparison with a stock Chevy 12 bolt rearend I think they are similar.
But on a Chevy 12 bolt you can upgrade to c-clip eliminators and better parts everywhere.
If using the heavy duty axle you are stuck with what you have.
Is this correct?

by dynchel Mon Dec 23, 2013 9:53 am

dynchel wrote:

This might be for that rearend. I bought it on eBay, suppost to be from a '78 camaro, but the numbers don't match anything i can find for a camaro. my research says its for a pontiac rearend.

this carrier has ten ring gear bolts. rendeer

by w451973 Tue Dec 24, 2013 6:16 pm

Spang wrote:If using the heavy duty axle you are stuck with what you have.
Is this correct?

Yup, pretty much. I don't think you'll have any problems with it handling 400 hp's. If you're worried about it you can always send it my way. I could use it in my Vista Cruiser.

by w451973 Tue Dec 24, 2013 6:22 pm

dynchel wrote:
dynchel wrote:

This might be for that rearend. I bought it on eBay, suppost to be from a '78 camaro, but the numbers don't match anything i can find for a camaro. my research says its for a pontiac rearend.
this carrier has ten ring gear bolts.

No because it only has 10 ring gear bolts. Don't hold me to it but that may be for a 8.5 ten bolt with bolt in axles. It sure looks like it me. Have you counted the axle splines on the side gears ? You want 28.

by dynchel Tue Dec 24, 2013 11:24 pm

I believe there were 28.

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