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

I figured since we have so many Pontiac/Olds rearend threads out there we could try to narrow some of the good info down to just one thread...so I've got some questions to ask and I'd love to get them answered, along with posting other helpful hints from some of the other threads...

'57-'58 Pontiac/Olds carriers...open and posi casting numbers for ID'ing
'59-'64 Pontiac/Olds carriers...open and posi casting numbers for ID'ing

'57-'64 Pontiac/Olds ring and pinion backlash, what is the proper setting for changing gears to get them just right?

'57-'58 Pontiac/Olds axle housings with '59-'64 third members in them, what is needed to make the swap? custom axles or modified stock axles?

Are Pontiac and Olds axle components interchangeable?

What are the stamped numbers for gear ratios?

Which backing plates/brake components/bearings/seals are interchangeable?

Where can you get clutch discs for posi's?

Post whatever info you can guys, let's make this a good resource for everyone to be able to look at without having to search through 8 different threads or starting new threads for answers...

 

1956 Code
3.08 0
3.23 9
3.42 8
3.64 6
3.90 4



1957 Code
2.56 3
2.69 2
2.87 7
3.08 0
3.23 9
3.42 8
3.64 6
3.90 4
4.10 1
4.30 5
4.56 *
4.88 *
5.14 *
5.38 *
5.57 *



1956 and back have 10-spline axles. 1957-58 are 29-spline and 1959-1964 are 31 spline.

No one is making new 31-spline side gears at this time, which is not good.

Richmond Gear calls the 57-64 Olds/Pontiac rear a GM 9.3" Axle (the ring gear is 9.3 inches).

"Hy-Tuff" axles are available for it from Moser and Mark Williams in any length (needed to put a 59-64 posi in a '57 case); thick gears are made and small parts and clutch packs are available. There are 4 types of limited slip units: Dana, Eaton, Detroit Locker and Gleason-Torsion.

I was surprised by the wide variety of ratios - must be, you want the rearend with an asterisk stamped on it for the good stuff.

(I'm not certain, but I think these stampings are good up to '64)-Johnny C. (info taken from another thread, posted by rustynewyorker)

 

Not that it will necessarily help a lot, but I DO know that according to my Hollander, 1956-1958 use the same rear wheel bearing (Hollander shows RW508D), and then 1937-1955 & 1959-1964 share a different wheel bearing (88128 - the 59-64 show 88128R, but it should be the same).

As far as I know, this only applies to the Pontiacs. My Hollander shows the same part number (88128) for the 1937-1964 Olds rear wheel bearings.

Autozone's computer shows the same Timken number for the '57 Pontiac and Olds (Timken 514003P - $14.99 ea).

Also, I was quite surprised to find that Autozone stocks the bearings for my '57 Pontiac (although these do NOT have the O-ring groove like the factory bearings), and Fel-Pro still makes axle flange gaskets and pig gaskets (Autozone was able to special order them for me, both listed in the computer as "differential cover gasket", the pig was "with 10 bolt cover" - RDS6431, and the axle flange was "with 4 bolt cover" - 4541.).

(originally posted by Hot Rod To Hell in another thread) Johnny C

 

Just a heads up about the pinion turn a bunch before the axles move.
That was my situation when I first swapped a 57 Olds axle into my 57 Chevy.
Drove it a couple months like that with a major "clunk" from on power to off.
Finally pulled it apart to find the shaft for the spiders had worn a slot in the
diff case. Iirc the spiders were galled to the shaft hence my "posi".
Unbelievable that it hadn't broke because the slot worn in the diff case was
within a 1/2" of the "windows"(for lack of a better description). Much less
the beating that pin had been taking.

Truly hope this is not your situation,but your description of the pinion
slack brought a lot of memories rushing back.

(originally posted by Ramblur in another thread) Johnny C

 

There are two styles of posi's-- 1) the Dana/Spicer Powerlok posi (bolts together with 8 bolts), which was used from '58 to early '63 (not sure if it was available in '57 or not), and 2) the Eaton posi (one-piece casting, like the later GM posi's), used from late '63 through '64.

There are two axle spline counts available for the Powerlok-- 29 spline ('57-8 rears) and 31 spline ('59 to early '63). The Eaton's all have the same 31 spline.

There are three ratio ranges available for the posi's. 1) 2.56 only, 2) 2.69-3.23, and 3) 3.42 and steeper.

You can fit 3.42 and steeper gears on a 2.69-3.23 posi if you use a 1/4" thick ring gear spacer.

Lots to know about these rears, hope you can figure it all out

(originally posted by Blownolds in another thread) Johnny C

 

rear gasket fel-pro RDS 6431
pinion seal chicago rawhide 19438
axle seal chicago rawhide 15005
carrier race SKF LM104912
carrier bearing SKF LM104949
inner pinion bearing SKF HM804846
inner pinion race SKF HM804810
outer pinion race SKF HM89410
outer pinion bearing SKF HM89446

(originally posted by 8th Grade Genius in another thread, I believe these are the parts #'s for a '57-'58 Pontiac) Johnny C

 

http://www.jalopyjournal.com/forum/showthread.php?t=128884 here's a good info thread on posi's and parts interchangeability...can anyone post the casting numbers for the posi carriers to determine which gear ratio and spline count the posi carriers are for?

 

http://www.jalopyjournal.com/forum/showthread.php?t=38805 here's a thread started by Littleman about Olds/Pontiac rearend ID...

 

'57 Poncho housing dimensions 55" flange to flange (Olds is 54")
'58 Poncho housing dimensions 55" flange to flange (Olds is 54")
'59 Poncho housing flange to flange 59 3/16"
'60 Poncho housing flange to flange 59 3/16"
'61
'62 Poncho housing flange to flange 57 3/4" need confirmation on this
'63 Poncho housing flange to flange 59 3/16"
'64

'57 Pontiac third member will bolt into '57 Chevy housing (checking to confirm axle choices for swap)

'59-'64 Pontiac third member will bolt into a '57-'58 housing with modification and custom axles (custom length 31 spline axles)

Splined side gears for carriers are NOT interchangeable between open and posi carriers due to different diameters of their mounting location/different carrier design...(still trying to confirm if 29 and 31 spline posi side gears can be swapped between posi carriers, it appears as though they can be, but no luck finding how much work is involved with making them fit)

 

I made a goof on the splined gears, what I meant to say was that the splined side gears are NOT interchangeable between open and posi carriers due to different dimensions of their mounting location...I'll go edit it now...

again, the 3 styles of carriers in both open and posi are

1)2.56 ONLY
2)2.68-3.23 (3.42 and steeper gears can work with 1/4" spacer)
3)3.42 and steeper

[the 1/4" ring gear spacer for running 3.42 and steeper gears on the 2.68-3.23 carriers are no longer being made, they can be found here and there on auction sites and at NOS parts sellers...they shouldn't be used for any hardcore drag racing since they have a tendency to bend ring gear bolts and contribute to ring and pinion backlash problems creating worn gears and howling noises...]

please guys (blownolds, Rocky, rustynewyorker, etc) add some info, like the casting numbers for the posi carriers to determine spline count and usage, the width cut-off years for the chart I started (along with Olds measurements), I need info for axle lengths (drivers side and passenger side axle lengths, for both Pontiac and Olds)...

 

Nice info thanks for posting.

 

it's just getting started, hopefully once I can get my hands on a hollander and some other information I hope to have a VERY thorough guide here for everyone to use...I'll be posting some identification pictures soon once I buy a new digital camera...

 

Well, if we're going to make a true tech thread, we should get it right. I didn't have but a minute to glance at what has been written so far, but just in glancing I saw a couple errors.

1) '57-8 rears are 29 spline, not 28 as was stated.

2) the internal side gears of the posi's (both styles) and of the open differential won't fit because they are of completely different designs. Has nothing to do with dimensions.

Maybe I'll get a chance to review the rest, but right now I've got too many things burning in the barrel right now.

Only thing I'd add at this time would be that I seem to recall the '54-6 rears as having possibly 16 splines, while the 10-splines were earlier. ALTHOUGH the aftermarket has made 10-spline spools for '57-64 rears (not sure if they copied a truck spline or the earlier Olds/Pontiac spline). 10-spline was really early rears, 29 spline was '57-8, and 31 spline was '59-64. I seem to remember there being something between 10 and 29 for '54-6 or so. Maybe someone here has taken axles out of those years and can tell.

 

different design, dimensions...figured that was saying the same thing...as for the 28 spline, whoops, my bad...should have caught that one myself...

 

actually, one of the stated 29 spline comments came from you, copied and pasted by myself from another thread...so HAH!...hehehe...

 

The info I posted came from Rick Gonser, who can be found on the yahoo list pontiac-1950s - he's been building '50's Pontiac racers since they were new cars. I'm curious if the codes apply through '64 myself, having a '64 Gran Prixe to part out with a 4bbl motor and I'm not sure that a limited slip was standard in them or if it might have an option code anywhere on the car for it.

 

DOH! I'll have to find that and edit it.

 

Hmmm.. can't find that thread you alluded to. Only ones where I said 29. Post the thread link and I'll correct it.

 

http://www.jalopyjournal.com/forum/showthread.php?t=128884&page=2 there's one

http://www.jalopyjournal.com/forum/showthread.php?p=1450810#post1450810 and another, in reference to my question about any spools having been built for the '57-'58 rearends...

no worries man, I already had to correct a bunch of mine, we're just getting old...that's all

 

I've been saying "29 spline" all along... 29 is what it is. NOT 28.
Looks like you aren't understanding what I said earlier in this thread. Here is what you need to edit (posted earlier in THIS thread)

 

DOH!!!...how the hell did I get that ass backwards?...holy crap man, I need to get more sleep...now I gotta go back and RE-edit everything...fun...

 

Alright guys, I need to find out the proper ring and pinion backlash setting so I can swap in my posi carrier once it gets here...anyone have a reference manual or know from experience?

 

According to my '65 Glenns manual, it should be .007 to .008.



jerry

 

hey just wondering, me and cj rebuilt his 56 pontiac rear(bearings inside) and ive never taken the gears apart from the housing. whats the proper gear alignment/centering, like...... how close is the ring gear supposed to be to the pinion gear??? we have it set with hardly any slack right now. how do you even set one up?

 

Quick question, I'm looking at a '50 Pontiac and was wondering if it had a torque-tube or a driveshaft. I've heard 'prolly torque-tube' from most that I've asked...

 

I've got a friend that sets up rears. He uses different amounts of backlash depending on the expected usage of the vehicle (i.e., drag race, or 100K-mile cruiser).

 

My friend's stock '41 Pontiac is open drive, so I would imagine that the '50 is as well.

 

Does anyone have a part number for the wheel studs on a 56' Olds rear? I need some and the parts droid couldn't looks them up, and was unable to match them up also...

I might have to pull the 56' olds rear end and swap in a S10 rear at the rate I am having issues with this rear.

 

I can't find a wheel stud part # listed on the NAPA website, so you'll either have to search around online or just measure the holes your wheel studs go into, pick a length and go pick some up...

as for Zach, I am assuming the procedure for setting one of these up for backlash would be the same as a conventional rearend, you shim the carrier side to side to get the proper amount of rotational play (in this case .007 to .008) from when the ring gear hits touches the pinion and then takes up the slack in the other direction...

 

Just in case anyone is wondering, it's open drive. It was also a rustbucket, so I'm not the owner of a '50 Poncho...