Caddy rearend strength?

How much abuse can a 1959 Caddy rearend handle? I'm looking to throw some big torque at it in a pretty heavy car on pie crust slicks. Will it live or should I avoid the blowing it into pieces phase and just swap in something else?

 

I'm gussing given the factory torque that cads are known for means your fine. I'd run it till it dies--then swap it. IMHO

 

IIRC, weren't the late fifties Cad rears were pretty much the same as the 9 3/8 Olds/Pontiac rears?? Just the housing widths/mountings are different??

 

Any more thoughts? Somebody out there must have some experience with these.

 

they are big and strong, but not rebuildable if i remember right.

 

Its supposed to be fairly stout the Cadillac drop out 3rd member hogs head rear diff.
Never ran one, but what I have heard.
Hard parts to rebuild may be a problem when the time comes.
May have search hard for them on ebay & forum parts for sale sections.

1957-64 Pontiac & Olds 9.3" inch rears are my personal choice.
I have a 1957 Pontiac rear with 5.57 gears with Henry 31-spline axle shafts & spooled,
a 1957 Olds Rear 3.42 open complete minus brake drums,
one in my 1963 G.P. with 3.23 factory 4- pinion Dana powerlock posi unit.
Another 1963 Pontiac G.P. 3.23 but open unit complete.
Then a spare complete drop out 3rd member with Dana powerlock & 5.38 Scheiffer gears.
Place to go for parts for these 57 to 64 Pontiac Olds rears is Fabcraft in Texas.
He has a book out now that tells all about these rears, restoration, rebuild, & setup parts for full drag use.
It was worth the buying price on ebay for Brad's- Fabcraft's book.
Very cool vintage racing photos inside.

Installing the 57 Pontiac rear into my 87 Corvette convertible. 4- link.
ditching the IRS setup.
Drag race in mind.

BR

 

How much power are you talking about and what car are you talking about ?
Personally if I want a rear to abuse and not let me down , then I always use a Ford 9" rear ! Then I never worry about if the rear will break or not .

Retro Jim

 

..... no first hand experience, but that's my understanding.

I can verify what others have posted, Cadillac serviced the entire unit as an assembly..... no internal parts were available. If what I have heard about this axle being the same as other GM cars, parts from this axles should fit the Cadillac. Other GM cars could also be a source for non-Cadillac ratios.

 

The O/P could try cross referencing the pinion bearing numbers between the cad and a '57//61 Olds rearend, if they match, that would be a good indicator...

 

All steel 1959 Cadillac, full interior street car with a 500 c.i.d. Caddy engine with a blow thru Paxton at about 7psi, th400 trans. I'd prob. run about a 3.50 ratio. Should make on over 600ft.lbs. Not a full race effort, just a big ole street car that runs better than people might expect Wide whites on the front, Whitewall Piecrust slicks under the skirts on the back.

 

Ford 9 inch is the most popular choice still.
They were made from 1957 to late 1987.
Millions were made.
You are going to make enough torque to twist most any stock axle shaft in 2 with a few dozen hard launches or less.
Will not matter what type of rear differential it is.
Best production Ford 9 inches had the nodular iron 3rd member drop out hogs head. Cream of the crop Mustang musclecar era Big Block Ford engine packages typical.
No one wants to give them away for next to nothing, difficult to obtain today.
Currie Enterprises has a great website for researching more.
You likely will need their parts, Mark Williams, or Strange Engineering.
I have used Strange Engineering Parts for Drag Race prior.
Excellent workmanship & materials. Correctly chosen parts won't fail from them.
Mark Williams is famous for making the very best racing rear differential parts anywhere. But you have to step up to the batting plate & pay $$$ for those parts.

 

Thanks for all of the advice!

 

If You don't do 100mph + wheel speed burnouts & hookup all the sudden, you should be OK on the street with standard radial street tires using the Cadillac Rear End.
I often wondered how strong those old drop out 3rd member Caddy rear diffs were for high performance use too.
The main housing & semi floating axle shafts have to be fairly stout. Most Cadillacs were huge American Tanks on 4- wheels.

The weakest link in many rear differential production designs are the center carrier assembly that mounts the Ring Gear & the splined end axle shafts slip into to.
When the cast iron carrier fails, scrap metal goes everywhere and being encased in a small enclosed round box, flying steel & iron parts have no where to shoot out of.
Bang....goes inbetween the ring & pinion gearset and severe damage is often the result.

 

Just read this closely, you dont really need to worry about what rear you put under it, it won't hook hard enough to break anything. Seriously...

 

Yeah, I think you're right. I just hate breakin'. I try to go overkill every chance I get.

 

Maybe off from the original question, but, does anybody make a whitewall slick that gets decent traction?

 

Caddy rear end are stout. Ring gears are riveted to the carrier. In '59 you had 2.94 standard. 3.21 on A/C cars. Series 75 Limos had 3.36 and hearses could have 3.77.
Driveshaft tube and center support bearing/carrier would be the weak spot.
Find a pumpkin with the gear ratio you want and "smoke-um if you got-um".
Ratio ID is stamped on the front face of the carrier at the end of the oil return passage.
2.94 is code 2
3.21 is code 1
3.36 is code 6
3.77 is code 7