57 Olds rear end question

What 57 Olds cars would've had a posi rear end? Is there a casting # to look for? What Pontiac rear ends of the same vintage are good as well?

 

That's easy....none. Positraction wasn't available in the Olds/Pontiac style rear until '58, and then not very much. '59-'64 posi center sections are more likely to be found, but use different spline axle shafts than the '57-'58 centers.

 

Would it be ok to ask why you are asking? What were/are you planing to do?

 

I've just allways heard the older guys brag on how tough the 57 Olds/Pontiac rear ends are. Are 3rd members from later models interchangeable into the earlier cases?

 

The guts are strong ,but the housings are flemsy as hell.I saw one in under a 55 Chevy that got smashed in where the axle pads were welded to it on both sides from moderate wheel hop,and when i say smashed it looked like some one had beat on it with a sledge hammer after heating it with a torch.Most other rearends have thicker axle tubes that are pressed in to the center section .Olds / Poncho rears are all one piece.Looks neat that way (especially when chromed) ,but not too strong cuz its thinner than other rears where it counts...

 

Hey superjunkman,

Just wanted to chim in on the Pontiac rear end. I have a 57 Pontiac Posi 3rd member in my Willys. Let me know if you need some Pontiac-Olds rear stuff. Got a couple of 1960 model posi. 3rd members that I would sale. 31 spline.

Gary

 

They're the hot ticket for a vintage racer because they bolt into 55-57 Chevys.

The skinny is this - a 59-64 Pontiac posi center will fit a '57 housing, some clearance work needs to be done with a grinder - but axles to work with it are hard to find because whoever (Moser?) was custom making them with the right splines and length, discontinued them.

If you're changing the mounts anyways, you can just get the later rearend - the Pontiacs are a bit wider than the Olds.

 

What do you have Gary?

 

back in th 60s 70s pont-olds was it. to lock it up we used ANSEN SPIDER LOCKS crude stuff . ran a posi it was spicer type . bolt together . sheared them two. next came the SPOOL . we got one of the first ones from HENRYS MACHINE SHOP. BELLFLOWER CA. and 31 spline axles. In the mid 60s it was hard to get gears. then PERFECTION GEAR came out with them. THE GOOD OLD DAYS.

 

I've been running a Olds/Pontiac rear end under our Fiat since 1965. Only problem I have had was breaking axles..Replaced them with Moser units, and have never had a problem since.. The weakest point internally is the caps..did rip off a few teeth on a ring gear once..

 

We also broke axles are cars were over 3000 lb . later on we ran a B-A roadster olds rear breakage NONE. 1900 LB.

 

Had a 57 poncho under a 56 chevy-had Henry's Axles with a 6.14 gear. 11.80 in the quarter with a full steel car, 2 ft. wheel stands 1st and 2 with 7000 rpm launches. Aluminum rod 327. Awesome, and never broke anything in the rearend. Finally twisted a driveshaft and gernaded the 327. Ran a hemi 4 speed behind it. Absolutely great rearend in my opinion. Dana 60 and Ford 9 inch came along and made the poncho obsolete. Good luck-oh, if you look on ebay sometimes, Mickey Thompson made a magnesium center section for the poncho rear-very cool.

 

In 1976 we ran a chevy powered ford mav 327 ci in pro gas class sacramento cal, 9.50 heads up . It had an olds rear 5.14 14/32 tire liberty top loader 4 spd . never had rear problem. THE GOOD OLD DAYS.

 

There is alot of new stuff available now at Fabcraft Metalworks, gears, bearings and he was supposed to have new posi units as well.

http://www.fabcraftmetalworks.com/index.php?id=10010&CategoryID=6

 

Does anybody have a posi for the 57-64 Pont/ Olds rear ? What kind of numbers$$?

 

I have a o/p in my dragster. they are heavier than a 9''. the center section with a spool is also heavier. have a new set of 4.10 gears. just not enough hp to pull them.

 

Might have better luck in the classified wanted ad section.

 

OK, I got this one. Yes, like mentioned above, NO posi for 1957 for Olds/Pontiac. First year 1958 for Posi. However these where 29 spline, axles and units. Pleanty strong, very rare and hard to find a 1958 Posi 29 spline posi unit, just because there is just not that many out there.

59-64 Olds/Pontiac went to 31 spline. Probably even stronger.
Any 59-64 Olds/Pontiac posi unit will bolt in a 57 Olds housing, however like mentioned above with a die grinder jyou just need to grind 4 little spots in back of the housing for clearance, 2 mintues job. But you need the 31 spline axles, and they have to be the corrrect length, a long story on that.
Also like mentioned above "Fabcraft" does make axles and the owner there Brad knows his stuff on this. Purchased my axles from him for around $400.00 complete.

For the posi carriers I have seen them go for $600-$800. I believe there are 4 different type "series" carriers, watch what gear ratio go on what carriers, then you get into spacers and some will not work with others etc. Again Brad at Fabcraft knows!

The picture is my 57 Olds true factory J-2 car, Super 88, Two door hardtop with a 3.64 posi unit out of a 1964 Pontiac Bonnieville. I put it in over the winter, works great.
For more photo's check out my Photo album on this site.

 

So, does a posi take different length axel shafts than an open rear end? For example, would a 60 Pontiac axel with a posi, have different length axel shafts than a 60 Pontiac axel with an open rear end?

 

Nope, same axels length as what orginally came with car will work in a posi unit as long as it the correct spline. So yes a 60 Pontiac axles will work in Posi unit that came out of non-pois unit. I was just saying in a 57 Olds if you went with a 31 spline carrier you do have to get axels made, they just do not come that short in 31 spline to work in a 57 Olds Housing.

 

Hey BushWacker! Did you happen to run a car by that name in the late ‘60s? I remember a car named “The BushWacker” at Sacramento Raceway. I bought, raced and eventually scrapped “the Bracket Jumper” ‘61 Impala bubbletop. I bought it in 1976 from Rich Grob. He had bought it from Don Diccero. When I ran the car it was running a Rex Hutchinson prepped 409, Hemi 4spd and a 57 Pont w/4:88s we ran a best ET of 11.71.

 

If you want some sage advice, call up Fabcraft and order there posi unit, it's $700 I believe. I only run Olds/Pont and run 4.11 to 4.88 ratio's. all the good stuff in them including a MW billet cap on the one side. To be honest if you can't afford to play with the Olds/Pont. stuff you would be better off with the Ford 9". I have several posi units some need rebuilding or a spider gear but I won't sell any for less than $500. After I got done rebuilding one it was almost as much as a NEW Fabcraft. Needless to say I'm annal and won't run Fords in my GM cars so I pay.

Pat