41 Century 3.9 rear fitting a 40 Super?

[Daves1940Buick56S]

I have a 40 56S with a 4.4 rear. Will the pinion, gear, and carrier from a 41 Century 3.9 fit my car?

Cheers, Dave

[1939_Buick]

Yes. Well worth doing

1940-1955 interchange. But you may need to use the 1940 torque tube. Put a tape measure over the torque tube

[Daves1940Buick56S]

To clarify, not the whole rear end, just the guts. Should not need to change torque tube unless new pinion won't fit I would think. But maybe I am wrong?

Cheers, Dave

[Ben Bruce aka First Born]

Dave, I replaced the complete gear set in my 1950 with one from a '54. A bit of a chore, but nothing you can't do. The most difficult part is getting the propeller shaft off the pinon.

Ben

[1939_Buick]

... The most difficult part is getting the propeller shaft off the pinon.

And back on again. That why if you can swap out with the torque tube is simpler if the same length. But as above is possible to swap out the gear set with carrier housing only. Just do it. Edited December 10, 2012 by 1939_buick (see edit history)

[Daves1940Buick56S]

Never mind. He sold it. Sigh. Well, I did see a 39 tooth ring gear for sale for $175 (meant for a 10 tooth pinion which I have). But how risky is it to put on a new ring gear with an old, presumably non-matched, pinion?

[1939_Buick]

A matched ring & pinion would be more desirable. Buick seemed to change part numbers regularly, even for the same ratio

Too late for this also http://forums.aaca.org/f117/1941-buick-century-rolling-chassis-sale-341180.html

[Ben Bruce aka First Born]

Never mind. He sold it. Sigh. Well, I did see a 39 tooth ring gear for sale for $175 (meant for a 10 tooth pinion which I have). But how risky is it to put on a new ring gear with an old, presumably non-matched, pinion?

Shop manual says Buick only sold and installed as a matched set. Look for later 3.6 or 3.4, unless you can find the complete torque tube/rearend that is the same length.

Ben