Technical Pontiac/Olds Rearend TECH...post it here...

just bought a olds/pontiac rear can anyone tell me the year its is . the casting numbers are
516744
and e225 on the pumpkin?

 

516744 is a 1954 number, tho any 'year' number may have been used after that.

 

i was told it was a 55 pontiac but wasnt sure.disassembled the rear end earlier today.found that it had 16 spline axles.can i buy a posi new or have to find one used.or what interchanges.also what is different between olds rears and pontiac rears.

 

I too have a 57' Olds housing for my 56' Chevrolet Sedan Delivery. Already sold the 3.42 open 3rd member to GMC Bubba. Course I've updated to 31 spline Strange axles, and have 2 31 spline posi equipped 3rd members; 4.88;1 gears on an Eaton unit, 5.38:1 gears on a Power Trac. Now, I have 2 sets of 57'-58' 29 spline axles I have NO USE for, one set has NEW bearings and wheel studs. Anybody interested in them for shipping only? Are the 57' and 58' Olds housings the same, down to the spring perch locations?

 

pm sent

 

A couple more little tidbits: For those of you using one of these rearends, for STRICTLY drag racing, and don't want or can't find the correct posi or spool for your axles/carrier, there is another option. Ansen Automotive used to make "Spider Gear Blocks" that took the place of the spider gears and essentially locked the carrier up; there will be NO differentialling effect for cornering. They were somewhat square looking with gear bevels on 2 sides to engage the side gears, but the other sides were flat. This puts all the stress onto the cross pin and carrier. They are no longer made, but do occasionally turn up on that aution site. Some old drag racers might still have some. And then, there's always welding, but the sanctioning bodies no not "allow" it any longer. I've already been through all this madness trying to put a 57 Olds housing together for my 56 Sedan Delivery. I'm finally set! EDIT: Just went to that auction site and low and behold there's a set on right now (not mine!);search under "Ansen".

 

I dunno about you guys, but I wouldn't want any more stress on my cross pin, I've had 2 of my 7 rearends have cross pins nearly coming out the carrier...at least there's still the option to use those instead of having to find a posi...I have yet to find a spool though.,

 

Mark Williams has a 35 spline spool for the 57-64 rear ends.

 

Does anyone make 31 spline spools though?

 

We are under rain and snow here. I found a 1957 Pontiac complete rear end of which must be removed from the 1957 Chieftan but weather has caused the seller delays. This 1957 Chieftan rear end will be having most likely 31 spline Pontiac posi then going under a 1957 Chevy Gasser.

Of interest is if the old 60's Buick 45 or 90 finned aluminum drum brake assembly with backing plate ect will bolt onto the 1957 Poncho rear......Please input.

 

31 spline spools are still being made/sold. Lots of used ones available too. Lots of 3rd members, open and posi, around. BUT, this stuff is starting to demand pretty good money, like everything else.

 

Maybe I'm lazy, but why have custom 31 spline axles made for a '59-'64 pumpkin in a '57 housing...I thought you found a '63 posi rear, why not use that by adding leaf spring mounts to it?

 

Coz the 1963 31 spline is coil spring based and too wide where the 1957 Poncho housing is leaf spring based just like the 57 Chevy and also same width and is supposed to be a drop in fit correct?

 

57 Pontiac rear is a bolt in to 55-57 Chevy springs. Very common swap in the old days, we have a '55 Chevy that was built as a drag car in '62 and has a '57 Pontiac rear in it.


Anyhow, I cut the rearend out of the '64 GP finally. There's no visible difference in the external part of the carrier from an open to a limited slip rearend? The thing sat for ages with only one rear wheel - when I took that one off I broke all three of the studs that had nuts on them - and it's entirely possible if it had a tag, that it rotted away (as has a lot of the frame on this car). I didn't track down the pad for the stamped code, but I did note signs of yellow paint on the right side of the carrier towards the yoke. Based on the reciepts in the console compartment it was last on the road in 1971 or 1972, so I'm doubting it was something anyone did, although I do see signs of the car having been apart and repainted (lots of missing bolts in the rear trim and lights and a row of holes filled in the right lower quarter).

It's looking like to go further into it I'll have to destroy the brake drums, even using a puller I think it will warp them to hell. Once I get that far, is there any simple way to pop the axles out? I have a '59 shop manual to check out, but I haven't looked at what's involved yet - just assume they have to come out to get the center out of it and get a look at it. Worst case I learn something, find out it's an open, and scrap it.

 

Don't want to wreck stuff if I don't have to, I have a guy who might buy it even if it's an open -

 

Hey all, its in the thread from when I had to go through the rear end of my 56 earlier this spring, I made my own gaskets. Scanned the old ones in, drew them up in illustrator and sent them to my vinyl cutter. Cut them out of manilla folders, no leaks as of yet. Ive got the plot files or an make more if any one needs em.

Ed

 

Remove the 4 retaining cap bolts on the end of the axle tubes for each axle and slide-hammer the axles out...I've never seen a posi tag on these rears, just the stamp code...good luck...

 

Some of them had tags; I pulled a center section out of a '61 Star Chief that had a tin tag under one of the carrier bolts that read "Safe-T-Track".

 

just picked up an extra pumpkin with 3.90 gears.can anybody decode the numbers on the pumpkin.would like more info like what year it came off of ....506925..and h217.thanks

 

I had a 57 Pontiac rearend in my 36 Ford coupe for years but it finally came unglued after an exceptionally hi speed run to New York and back.
At the junk yard that summer I found a 63 Olds '98' with a perfect rearend.
Took it to a differential shop and had it narrowed 7 inches, welded some leaf spring style perches on it, shot the pinion angle slightly with shims and rolled it in.
Performs flawlessly.
Much easier to find seals, gaskets and bearings for a 58-64 Olds/Pontiac style verses the late 50's rearends.
Oh, by the way, when my Olds rearend was narrowed I had the guys weld on Ford Econoline big bearing axle ends and use 11" Econoline brake shoes.
Also easier to sevice down the road that way

 

need help?.the pumpkin i bought with the 3.92 gears looks to have a shorter yoke then the one that is on my car..the diff in my car looks way bigger.then the one i bought. on my rear end has a flat pad behind the yoke and the other doesnt.i had been told my rear end is 55-56 olds pontic.it has 16 spline axles..i have 3.23. and want a lower gear..also at the 3.o'clock positon on the third member in my car there is a 5 .any more help would be thankful.thanks

 

55-56 Pontiac and earlier used 10 spline axles. I havn't pulled the axles from the 41 but the carriers should interchange somewhat with a few minor differances. There are some notches in the housing in the later rears 55-56 for clearance for the larger ring gear, so a 55-56 carrier in an earlier housing would require opening them up for clearance. I suspect the main differance is the olds version of the early axles uses 16 spline instead...

 

thanks.will a 57-58 third member fit?in a 55-56 housings if the axles were changed to match the same year third member

 

No, 57-64 have a 9.3" ring gear and way to large for the earlier housings.

 

So are 57-58 Powerlok axles all 29 splines? Are the open rear ends for 57-58 also 29 splines? I have an extra set of 29 spline axles, will they fit in my open 57 axle? If not, what are they worth and is anyone interested in buying them? By the way this is all Pontiac stuff I'm talking about, they quit making Oldsmobiles!

 

All 57-58 are 29 spline. Either will interchange as far as posi or not. They are both the same length, MPC lists them as 29 21/32" long. There are differant part #'s for L and R, I suspect because of lh and rh wheel studs.

 

I have a olds pont rear in my 55 chevy possibly a 59 with 3 ribs on the pumpkin 5.13 gears with mini spool.I would like to change the ratio to a 4.10-4.30 but i need racing gears not street gears.can any one help me. thanks

 

I have a 1964 buick lesabre that I think has one of these olds/pontiac rearends. It has the big drop out section. Did Buick have thier own or did they use olds/pontiac.

 

i need to keep track of this thread...........

 

Ok, I took it apart. I have 29 spline axles so I assume that it is a '57 Diff. It measurs 55" from flange to flange. My measurement might not be accurate. I was alone when I measured it.
So judging from this information what do I have and what do I need to do to use this in my '55 Gasser. keep in mind I WILL beat the piss out of it.