Technical Pontiac and Olds Rear Ends

Years ago the go to rear end for diggers and other drag cars was the Olds and Pontiac 9.3 rear end. With it's drop out pumpkin it was kinda sorta a quick change. The question I have is just how tough are these rear ends?

Today I was able to score one of these early rear ends, and much to my amazement the guy I got this from had over a hundred Pontiac's from the late 50's to mid 60's. Not one of those hoarding story's were they will not sell anything. This guy is motivated to sell as much as he can. I ask him about a couple more of the rear ends and he is going to pull those for me and I will get them later this week, that way I will have a couple of extra center sections for the one I bought today. That and I also bought a couple of 389 engines and actually only had to pay core price. The rear ends though I would like to know if they were as good as all of the old story's.

 

They aren't bad. I ran one on my Super Gas Anglia for years with not a single problem. Strong, probably just under the big Ford 9". That's only because of the tooth contact pattern on the Ford. The Pontiac is between the Chrysler. 8-7/8" and the Ford 9", strength wise.

You NEED to stick to the 57 to 64 versions. Earlier versions aren't the same.
Also, there are two rib and three cases. Obviously the three rib are stronger. A little heavier, but stronger.
There is now, also a few companies making parts again, gear sets, various posi units, spools, the crush sleeve, gaskets, etc. Any axle company can build custom axles for your width.

Mike

 

Stronger than a stock 9 inch, but cost more moneys to build.

 

He should call Fabcraft! They'd be a great option to unload a bunch of rear end parts.

I spent a pretty penny on mine but comparing the costs it wasn't all that much more... building a custom rear isn't cheap.

 

Guys use to run dead stock Olds / Pontiac rearends behind blown Chryslers

 

I've got a complete one from 57 with later 31 spline side gears and axles to go with it. Hasn't broken yet sitting under the shelf in the garage.

 

Been running one for years in both LSR cars. Getting expensive but so is everything else. 2.56 is the highest gear set.

 

49-51 Olds was the unit used in the dragster, It was the same size as the 8 3/4 Chry that everyone switched to because of gear availability. 4:11 that came out of Ambulances were not readaly available when you needed one. Also consider that traction and tires were no where near things are today along with the cars weight. Now the much later 56-7 and up were a better rearend for G***ers and early F/C because they were larger, Hard to fit in an early dragster and still have the driver in place

 

Like with everything else it depends on what yo use with it. 14" wide tires and a 5.14 gear ratio in a 3000# car with 700+ HP and a posi, you will blow it. The pinion is the weak link it is very small. I run a rebuilt posi, 4.88 gears a billet main cap and yoke, with 500 HP and 12w tires. Wheels up launches with automatic. It's been in the car 11 years now without a problem. I'm a GM guy and wouldn't have a 9" in my 57 Chevy.

Pat

 

^^^This^^^; but, they're basically the same 37-56; the 10 spline axles were the bugga-boo, then the 9.3 came out in 57. Mickey Thompson even made aluminum and magnesium replacement third members for them (and the 57-64 models also). As far as the 57-64 models, stay away from the DANA Positractions; better to use the Eaton's. I had a 57 Olds housing, welded on the perches to fit my 56 Delivery, 31 spline Summer's brothers axles that I had to shorten 1" each, all new brakes/hardware, and two complete third members. One was a 4.88, the other a 5.38, both on EATON posi's, but I needed the room, they were always in the way, so I sold everything. Figured the guy who bought it all would give me a good price on rebuilding a 12 bolt I had for another project; he "retired" and would't even consider it. Should't have given him the deal I did. Somewhat well known "rear end guy" in the greater Seattle area, but I won't mention the guys name. I am Butch/56sedandelivery.

 

This book is well worth having. Everything you need to know about the 9.3 .

 

There are also some really good, comprehensive threads on the HAMB.

 

yea i have an early one 49-? in my fed. it has a m/t mag third member. it has shortened axles but i haven't toren it down yet.

 

Does his name start with an R and end with a Y?

 

I agree 100% !! The big I ‘57-‘64 units are strong as hell. Add a 4130 cap girdle with studs and they are as strong as beefed up 9”. I will admit the one weak link is the side gears on the power lock/posi. The Rockwell tempering is too hard and brittle on the spider gears for drag racing so a spool is a better choice . They are also the correct rearend for a period g***er and make the Ford 9” look like a toy by comparason


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I'm not so sure about that Q!

 

Question guys. I have an olds rear ***embly in place in my 40 ford coupe. It is big and stout. I hammered on it pretty hard with the 371 olds motor in coupe. I had a difficult time finding rear seals for the unit. Also it is
not a posi, which probably helped the longevity. Are there posi units for this rear? Also where can seals be found. I think it is a 1950 issue as that is the transmission in the car. left hand thread studs on the left side as well. Thanks for any information.

 

No, different guy apparently. Not "Randy's". Sounds like Nick Jerkowitz. I am Butch/56sedandelivery.

 

Fab Craft has the very best indestructible 31 spline posi. Brad the former owner if Fab Craft totally redesigned the later model Eaton and got them to manufacture it . They also sell new gears , bearings , seals ,crush sleeve or the far superior solid steel pre load sleeve with shims .
And for the record here on this topic . Builders of drag cars slowly moved away from these big beefy rearends ad the supply at wrecking yards dried up in the late ‘70’s. The Ford 9” is and has been plentiful for decades so that is why they are so popular.The fact is the 9” only is strong when it is fitted with the nodular pinion support . Yes the 9” has an extra bearing in the back side of the pinion but thats because it needs it to equal the strength of the big Pontiac/Olds 9 3/8”.


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Thanks for that I ordered that book from FabCraft tonight. FabCraft does seem to have most of the parts for the 9.3. Thanks everyone for there comments.

 

I have often heard rumors about these Old's and Pontiac rear ends from guys back in the day. I have been looking for a time for a period correct rear end for my Hot Rod. It has had a couple of rears in it narrowed to fit a Model A. One a 8.8 Ford I destroyed with a mild small block, and it was to new for me anyways. It has had a 9" ford but to say the truth they are just done to death, they also are no where's as plentiful as they once were. The 9" I had found a new home in a buddy's car. Right now my car has a 10 Bolt Posi in it and I am not happy with any part of that deal, to new, to ugly, and not strong enough by a long shot it just has to go.

That brings me to the Pontiac, Olds 9.3. I have always been looking for one if one ever showed up that is. Wasn't in a hurry but maybe if and when. This guy with a ton of these rear ends just happened up one day this weekend. The surprising thing was how many of the damn things he had. He even had a couple of those that take the weird Pontiac real wide bolt pattern, don't really know what you call those. So I bought that one as well maybe one day I will run across some guy with a car that needs that rear end.

Thanks for your comments guys...

 

I'd say the big issue was that as Quicksilverart46 said the readily available supply of complete rearends dried up pretty fast. You just flat ran out of easy to find donors in wrecking yards.
The nine inch Ford was produced in some form from 57 to 86. I've got three out here out of F 150 trucks that I have picked up over the past few years when I find a deal on one. I'll never put that much horse power to one but having a rear axle under the rig that can be repaired in a parking lot if I need to on a road trip has it's merits.

 

@mickeyc I have had good results with Olcar in NC when trying to find seals. Might give him a shout 910) 693-3324

 

Glenn Ways "GROUNDSHAKER" restoration has a Ford 9" fitted in a big Olds housing.

 

Here's that posi. Not all that much to see. I haven't run it, yet.

 

I just narrowed a ‘60 Olds 9.3 for my early ‘60s style ‘28 high boy. Mark Williams supplied the axles, bearings and seals. It’s a 3.42 Posi. I figured it’s the perfect rear end to go behind the Olds engine and old 4 spd hydro.
If I was racing my car regularly I would probably lean towards a 9” Ford just because of parts availability but nothing says period correct g***er like the Olds/Pontiac rear ends.


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I've been told that the '55-'56 Pontiac rear ends aren't much better than the '55-'56 Chevrolet.

 

Rodders Journal has these books available.

 

"Eight Lugs"

 

I had a 57 pont with Eaton posi and Henry's axels 31 spline I used with success in mid 60's. I also had the spider pinion gear problem and an old machinist friend told me to anneal them by heating in mom's oven for 2 hours and drop them in a can of dry portland cement. Solved the problem. He said they would wear easier but not break and it worked for me.