67Rocket

Will a 67 F 85 carrier with 2.73 ring and pinion accept a 3.23 ring and pinion? I thought I heard somewhere that pinion shaft diameters varied with ratio combinations. Appreciate it.

Fun71

Do you know what type of rear it is?

droldsmorland

Ring gear thickness and pinion gear diameter vary with ratio. 323 ring gear is thinner with more teeth thus you will need to space it out off the 273 carrier...If its an apples to apples carrier, EG both assemblies are for a O type axle assembly it will work. Again you will need a ring gear spacer and new ring gear bolts n washers, ARP of course. Along with new bearings, crush sleeve, seals, shim packs etc... Ill bet you found a 273 limited slip and you want to put your 323s in it?

67Rocket

The carrier in my car has a 12 bolt round bulged out cover (8.5?) with the 2 square lugs at the bottom of the carrier. Research shows this to be a 1970 plus style carrier assembly. Am I missing something here? Thanks.

67Rocket

Per Hemmings, All 67 Olds A bodies used the same carrier with a 8.5 ring gear with a ratio of 3.23 and lower and a different carrier for ratios of 3.42 and higher. Does this sound correct with you guys?

Fun71

The O-type was used from '67 up to '70. Starting in '71, the 8.5" corporate 10 bolt was used. If you have an O-Type rear (12 bolt cover, 10 bolt ring gear), there were three carrier breaks: 2.78 and lower, 3.08-3.23, and 3.42-up.

Info from Brian Trick many years ago:

O-Type 12 Bolt

Here is a list of the posi units & what gears they will fit:
#673 = 2.56 & 2.78 ratios, 28 spline
#671 = 3.08 & 3.23 ratios, 28 spline
#588 = 3.42 & anything numerically higher, 28 spline
#672 = 3.42 & anything numerically higher, 31 spline
***The 31 spline axles were offered in late 67-68 OAI cars only.

Note that the O-Type did not have a 2.73 ratio. If you truly have that ratio, then it is not an O-Type.

67Rocket

My typo error, this carrier has a 2.78 ring and pinion so does this mean I cannot change this carrier to a 3.23 ratio? Thanks for the info.

67Rocket

Question s/b change to a 3.23 ring and pinion? Thx.

Fun71

From what Brian told me way back when, a ring gear spacer could be used to install the 3.23 gears on the 2.78 carrier. He had some of these back then but you would need to contact him about current availability.

nsnarsk65cutlass

If it's casting #410408n it will work 2.73:1 & up #410409n is 2.56:1 and down this is for 8.5 rear 10 bolt rear.1970 up

Fun71

Correct, but note that he said it has a 12 bolt cover, so it is not a corporate 8.5" 10 bolt.

And that would be 1971 and up as the O-Type 12 bolt was used in 1970.

67Rocket

How do I get the spacer needed for the ring gear. How do I get in touch with Brian? Thanks!

droldsmorland

If you can definitively ID the rear end contact one of the many rear end vendors. I used Drive train direct and National drive train.

67Rocket

Thanks for the suggestions, the vendors I have tried tell me the ring gear is 8.2 but I believe it is 8.5 based on the round 12 bolt cover with the bulge in it.

monzaz

10 bolt 8.2 Pontiac Buick rears
2.56-2.78
2.93 3.08 3.23
3.36 3.55 3.90 4.33 4.56 4.88 5.13

12 bolt Olds (12 bolt cover 10 bolt ring)
2.56-2.78
3.08-3.23
3.42 - 5.00

10 bolt BUICK 68-70 (large 1.875 pinion and large driverside bearing)
2.56 only
2.73- 2.93
3.08 - 3.42
3.64- 5.00

10 bolt chevy 8.2
2.56 -2.73
3.08 -5.13

12 bolt chevy
2.56-2.73
3.08 - 3.73
3.90- 6.14
(aftermarket 3.90 can be in either 3 or 4 series carrier watch out)

10 bolt 8.5 corp (1970-2016) 30 spline pinion shaft spline
2.24 2.41 2.56
2.73 - 5.57

10 bolt 7.5 and 7.6 and 7 5/8 (they are all the same beast)
2.14-3.08
3.23-4.56

That should cover the cars....
Jim
J D

anthonyP

Thanks Jim. Can you please list the carrier codes for Olds 8.5 10-bolt axles and the O-type axles. Thanks, Anthony

Fun71

This info needs to be in a tech archive.

droldsmorland

They tell me the same thing. You need a knowledgeable tech on the other end of the phone. And verify the ID of the ring gear you have.

Try this...

http://www.oldcarmanualproject.com/m...Ill/Group5.pdf

Or this...

http://www.oldcarmanualproject.com/m...Ill/Group5.pdf

anthonyP

Thank you for the link, it was very helpful. Will need to check out the entire website.