'71 Olds Cutlass rear end (?)

48ford · Post by **48ford** » Thu Jan 12, 2012 3:51 pm

I’ve got a ’71 Cutlass rear end, but I have no idea what’s been changed on it over the past 40 years! I’m looking for some help identifying what I have left. I’m doing a drum-to-disc brake conversion, and replacing the axle bearings, seals, etc. while I’m at it. I think the ring and pinion look fine, but by my estimation, they might be a little “undersized.” Here are the facts that I do know, along with some pictures:

10-bolt cover, and 10-bolt ring gear
The code stamped on the ring gear is: “41416 GM KN 3512” (doesn’t that mean the gear ratio is 35/12=2.92?)
Axles are 28 spline
The code stamped into the front of the passenger side axle housing is very deteriorated, but I think it is “R2 0019 (then maybe a 6?)”
The code cast into the differential housing (on the side of the “pumpkin”) is 407296
The width between the flanges is 55.5”
The connection of the U-joint is 4 straight bolts with 2 straps, not U-bolts
The diameter of the ring gear sure seems significantly less than 8” (but everything I’ve read seems to indicate this rear should be an 8.5” or 8.2”)
On the internal bearing retainer, there is a large dimple (as if to keep the retainer in place; kind of like a dimpled retaining nut on the end of a CV axle instead of a castellated nut and cotter pin). Is that necessary, or shouldn’t this simply be press-fit? The replacement bearing retainer I’ve been given looks much different—it’s a lot thicker, so I don’t see how I would dimple it again.

I assume this is an Olds rear end, right? Am I measuring the ring gear correctly? What size is it and has it been changed? If I wanted to go to a bigger ring gear, what size could I go to?

[img]Z:\car%20repairs\1948%20Ford%20Coupe\Rear%20Axle\Differential%20cover.jpg[/img]
[img]Z:\car%20repairs\1948%20Ford%20Coupe\Rear%20Axle\Front%20left%20side%20of%20Diff.jpg[/img]
[img]Z:\car%20repairs\1948%20Ford%20Coupe\Rear%20Axle\carrier.jpg[/img]
[img]Z:\car%20repairs\1948%20Ford%20Coupe\Rear%20Axle\Measure%20ring%20gears%203.jpg[/img]
[img]Z:\car%20repairs\1948%20Ford%20Coupe\Rear%20Axle\2%20axle%20bearings.jpg[/img]

67drake · Post by **67drake** » Thu Jan 12, 2012 9:41 pm

I'm no guru,but I'm building a 71' Olds 8.5 right now, and it looks identical to yours.
I'm 99% sure that's what you have there.
BTW,these are very good rear ends! I sought out an 8.5 just to replace the 8.2 that came in my GTO originally.

Post by **monzaz** » Thu Jan 12, 2012 10:41 pm

Yep, 10 bolt 8.5 1971 1972 Olds cutlass original rear end.
Bolt In Axles 28 spline

Will bolt into all 1967-1972 A-body BOP
and
1968-1972 Chevy A-body cars.

ALL will require a drive shaft shortening Usually and on the chevy rears it will require a u-joint swap to a BOP / Chevy conversion joint.

If you need prices on any of the part for the rebuild PM or call There are MANY different combos of posi units gears etc that you can use.

We can even upgrade that rear to race 12 bolt chevy strength wit hMOSER 30 spline bolt in axles direct bolt in replacement with a 30 spline posi unit.

Take care, Jim
J D Race
330 659 7117

48ford · Post by **48ford** » Fri Jan 13, 2012 12:26 am

Thanks for the replies and your help!

2 additional pictures that I tried to upload did not, so I'm going to try again here. In particular, I'm concerned about the size of the ring gear. As you see in the picture, it looks very different (to me anyway) than an 8.5"!

Second, my question in the original post about the "dimples" in the internal bearing retainer: When I press on the new bearings, do I have to do something similar, or will the press-fit suffice?

Thanks again!
Todd

Post by **monzaz** » Sat Jan 14, 2012 1:27 pm

You can not measure the ring 9in the housing ...Will never work, You can not get to the actual MIDDLE if the ring. Trust me it si 8.5 ... It is the housing casting I am ID ing yuour rear by. The caps the housing the cover the yoke all ARE 8.5.

The axles. The need bearing and retainers WILL LOOK TOTALLY DIFFERENT than the factory stock stuff.

A9 bearing and 712146 is the seal part number.
You will NOT have a dimple in the retaining collar like the factory. It will be a thicker and tighter press fit then the factory small retaining collar.

IN Order you will put the retaining plate, Then the seal will be slid on with plenty of grease on the inner lip that rides on the axles. After that the bearing is pressed on (please be sure you are installing the bearing in the correct way so the race is in the housing first and the taper part of the bearing toward the inside of the tube.) Then finally the retaining collar which keeps the bearing from sliding on the shaft. Jim

You need NOT tack weld either...IT SHOULD NOT BE NECESSARY if the press fit is too loose then your axle is warn and will need replacement.

Jim
J D Race

48ford · Post by **48ford** » Sat Jan 14, 2012 4:52 pm

Jim,

Thanks for your reassurances--that's what I've been waiting for. Your knowledge (and willingness/ability to share great information) of this genre of axles is unmatched, from what I've found in my research on the entire-net.

Thanks so much!
Todd

ps--do you guys sell wheel lug studs?

Post by **monzaz** » Sat Jan 14, 2012 8:25 pm

Yes, How many and whta size?

Standard GM size is 7/16 x 20 they are $1.35 each

Jim

the plug · Post by **the plug** » Tue Jan 08, 2013 6:37 am

Thank you guys for all this info! All my questions I had about this rear I have has been awnsered !I have a 2.56 nonposi and swapped out my m20 for an iron case, iron mid plate super t10 with a 2.88 first gear to get me movin.Plan on going w/ a 3.08 posi now that I know what I have! Thanks again! 1968 442 455 stock rebuild crank drilled by a local gunsmith for pilot bearing

Post by **monzaz** » Tue Jan 08, 2013 7:01 am

We have 3.08 gears for that rear. You will need to swap out the carrier as it is only good for the high series gears 2.41 2.56 - Yiu need a 3 series carrier OPEN (non Posi) or Limited slip (posi)
We also have these along with bearings kits axle and center section master kits. Very complete kits.

So just more options for you.

Shoot a PM and will get you prices. Jim

the plug · Post by **the plug** » Fri Jan 25, 2013 11:52 am

How much would it be for the master kit? Posi carrier, 3.08 gears
Bearings seals

Post by **monzaz** » Fri Jan 25, 2013 9:46 pm

Price as of 1 25 2013
89.00 rebuild kit
60.00 3.08 gears
159.00 NEW 3.08 gears
69.00 for bearings and seals for the axles (does both axles)
289.00 Posi recondition GM 3 series
419.00 Eaton type posi clutch 400 preload performance posi unit

Plus shipping to ???

the plug · Post by **the plug** » Wed Jan 30, 2013 1:38 pm

How about a rebuilt 2 series posi for the 8.5?any in stock?

Post by **monzaz** » Wed Jan 30, 2013 8:35 pm

confused... Why do you want a 2 series posi now? Jim

We have them ... same price.

the plug · Post by **the plug** » Thu Jan 31, 2013 5:29 am

Not sure if I want to stay with the 2.56 or step up to the 3.08. The car is a great around town I leave it in 3rd. Hit the highway and 4th is like O.D. What would you suggest?

Post by **monzaz** » Thu Jan 31, 2013 7:56 am

That is fine by me. It is always up to the customer. so you have a auto 4 speed or manual 4 speed? Jim

www.jdrace.com

'71 Olds Cutlass rear end (?)

'71 Olds Cutlass rear end (?)

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