1965 Olds Cutlass Rear Gear

[oldduck1]

I just got my 65 Cutlass back from the shop. I had wanted to install a 3:08 posi unit to replace my 3:08 open rear. After a long search, by them, I was told no such gears are available so I went with the 3:55s. I'm not at all happy with this set up, too many rpms at freeway speed.
The rear end housing is a 10 bolt and has the two fins on each side with the top fins angled upward. (Pontiac?) The tranny is the 2 speed automatic.
They did install a new Auburn carrier P/N 5420113. Any help with higher gears?

[WMACHINE]

Jim will be along to correct me if I'm wrong, but:
Yes, the housing you describe is a "P" Pontiac 10 bolt gear, 10 bolt cover rear. That is the OEM rear for a '65 Cutlass. Unfortunately for you, the 3.55 is the highest (numerically lowest) gear for that carrier. The 3.23 and 3.08s require a different series carrier.
Where are you located?

[oldduck1]

Thank You,
That's what I was afraid of. Is there any other carrier that would work in this housing? One that would accept 3:08s.
Escondido, Ca.

[WMACHINE]

Yes, for sure. I believe it is basically the same thing, but takes higher gears.
Someone who has that carrier that wants steeper gears may be willing to swap you.
Jim?

[Frankie]

Why didn't they just sell you a posi carrier and reuse your old gears?

[WMACHINE]

I checked, and there is the Auburn 5420114 that is for the 3.23 and higher (numerically lower) gears that your 3.08 gears should fit, so I don't understand their "no such gears are available" answer at all.

[oldduck1]

I Stopped by the shop this morning, to ask why we didn't use my 3:08s. I was told the bolt pattern was different.
I see, with the number you supplied, we might have the wrong carrier. (113 vs 114)
That's not good!
I will be stopping by the shop later to see what we can do.

Thanks again for all your help!

Ken

[WMACHINE]

Wrong only in that it is for a different range of gears. Otherwise, it is exactly the same. The one you have is more for the "performance" gears, and generally more sought after. But I just don't understand the "not available" part.

[monzaz]

Ok, W is right. The company you got your posi from should have known there was a posi unit for the pontiac rear that would fit the 2.93 3.08 and 3.23 gears. Factory gears . That is a darn shame when stuff like this happens. This is the reason for the site PRIME example. You can ask before you leap.

We also have 3.36 gears that will fit the 113 auburn carrier you bought if you think that ratio would help. If you still have the 3.08 gears we have the correct posi you need and can give you something towards a trade in if you wish. Just PM me and will discuss what we can do and offer. Ok?

I have attached an image to help you under stand the carrier breaks and how if makes the ring gear move to the center of the case to engage the smaller pinion as the gears get steeper. Jim
left to right :
2.56-2.78 carrier 2.93-3.23 carrier and 3.36 - 4.33 and up higher.

[oldduck1]

I passed on your information to the guys at the shop, including pics. They will contact their vendor to see what can be done.

[monzaz]

Ok if not I have them here on the shelf. Jim

[oldduck1]

Hi Jim,

Just wanted to say thanks, for the valuable information you provided to me and my shop. Too bad I didn't take the time to find you guys, before a purchase was made. I assumed they knew what they were doing! Ya, the old definition of assume applies here.
I will be ordering a new carrier from you and will use my 3:08 gears. Hopefully I/we can find a buyer for the slightly used carrier and 3:55 gears.

Thanks again,

Ken

[monzaz]

I am sure you will NOT have any trouble unloading the 3 series posi unit...Just be sure you tell them exactly what happened so they understand how little use the posi has.

We could sell you Chevy 3.08 gears to retro fit the housing BUT that would really confuse the poor guys working on the rear.

Question?? did they remove your old pinion bearing from the 3.08 gears? Is the shim still in place?

If so just reset it all back in the housing bolt the ring gear to the NEW unit and set the backlash and your done. Even you could have done that set-up... That is NOT a put down on you...lol. I am just stating it is easy enough for most mechanically inclined personal to do.

I am here if you need help. Jim