Re: Axle and gear ratio interchange confusion

["Jim Blair" <carnuck@xxxxxxxxxxx>]

A: 2.87 is the break. 2.72 and 2.56 are on the same carrier.


From: TABunsey@xxxxxxx
Subject: Re: Axle and gear ratio interchange confusion
To: mail@xxxxxxxxxxxx
Message-ID: <ADVANCES62xzCnldxmr000014fb@xxxxxxxxxxxxxxxxxxxxxxx>

Marty:

There is no error in your logic. 2.87 gears WILL fit anyplace that a 3.54 
gear will fit. The eBay vendors are UNINFORMED and INCORRECT.

There is no difference (at least with Stock AMC gears). AMC ONLY MADE ONE 
CARRIER ASSEMBLY FOR THE MODEL 20 REAR AXLE (Well, actually there are two 
carriers--a "Twin Grip" carrier and an "Open" carrier).

LOOK IN THE AMC PARTS BOOK. ONLY ONE PART NUMBER!!!!!!

The aftermarket idiots keep saying that there is a "break" around 3.07 
ratio, or so.

IT AIN'T SO (AT LEAST AMC DOESN'T THINK SO).
I have pulled 3.54 gears and replaced them with 2.87 gears IN THE SAME 
HOUSING, SAME CARRIER.

IT BOLTED TOGETHER AND WORKED FINE. FOR YEARS!!! Behind a 401.

Alright, alright.
Yes, AMC DID use a different carrier for the Concord/Pacer V8 cars with the 
2.56 ratio. But this only applies to 1978-79 model year cars with an 
automatic and no "Twin Grip".

I have such a ratio I took from a V8 Pacer. I installed it in a V8 Rambler 
American rear axle. Works fine, too. Bolts right in as an assembly.

The AMC 6-cylinder rear end DOES require one of two carriers, and the change 
IS around 3.08. It looks as if the taller ratios have a pinnion gear with 
such a large diameter that the mounting flange on the carrier had to be 
moved outboard to keep proper gear mesh.

If I sound "touchy" about this, it's because I am. Every couple of months 
the same issue raises it's ugly head. Then it gets talked to death & 
resolved. Then a few months go bye, and the issue comes up again.

Arghhhh!!!!!

Boy, it would be nice if the list would permit "bold face", "underlines" and 
"italics" to emphasize various points. But since it doesn't, I need to use 
CAPS instead.

Tom Bunsey

My "bible" is the AMC Parts Books. After all, AMC built the cars, Not some 
aftermarket guys who think if it works that way on "Chebbys", it must work 

that way on everything else.