The Stovebolt Site Forums The Shop Area Driveline '47 transmission

I have a '47 Chevy with a 3 on the floor that jumps out of 3rd. The truck came with an extra 4 speed and bell housing for a torque tube. The assembly is too long for my rears tube. Is the 3 speed the same transmission as a pre war truck? What years? There is a '54 rear and tube assy on CL would this work with the spare? Are the 54 rears geared any higher? Thanks for considering possible solutions.

High gear on 3 or 4 speed is direct.

Take your 3 speed out and replace the bearings, they are simple, not expensive, learn something new.

Ed

Q.The truck came with an extra 4 speed and bell housing for a torque tube. The assembly is too long for my rears tube.
Q. What year is extra 4 speed?
What year is extra bell housing?

Q. Is the 3 speed the same transmission as a pre war truck? What years?
A. Do not know for sure.

Q.There is a '54 rear and tube assy on CL would this work with the spare?
A. Looking at the Master parts Catalog Shaft, Group number 5.441 (propeller shafts)
The torque tube propeller shafts are the "Type C"
It says, 1947 1/2 ton propeller shaft O.L. overall length is 65 7/16" used on both the 3 or 4 speed trannys.
It also says it uses 17 splines.

1948-54 1/2 ton (except Hydramatic trans.) propeller shaft O.L. overall length is 63 7/8" used on both the 3 or 4 speed trannys. 17 splines.
That tells me 1954 tube assy is to short for your truck, if using the original 1947 3 or 4 speed trannys.

Master parts Catalog Carrier Assembly group number 5.504 (torque tubes)
1947 1/2 ton is 62 1/2" used on 3 and 4 speed trannys.
1948-54 1/2 ton is 60 1/8" used on 3 and 4 speed trannys.
How to measure Torque Tube

Q. Are the 54 rears geared any higher?
A. 1954 1/2 ton ring & pinion gear ratio > 3.90:1
1947 1/2 ton ring & pinion gear ratio > 4.11:1

Solution; Rebuild 3 speed transmission.

Thanks very much. Your info provides options. The only thing about the 47 tranny if it needs some parts that prove difficult to obtain I hate to have it apart and unable to move. The spline count seems to be the key to finding a replacement.

That is what will probably happen. I'll let you know what I find.

Is yours an early or late 1947? Does it look like a 46 or a 48. 1947 was a mid year body change.
Here is my blog post on jumping out of high gear.

It is a late model 47, but it seems to have an early drive line. Many things changed in 48.

The transmission in a 47 is the same as 1940-46.
That is the only direct interchange.
Some internal parts from later transmissions are interchangeable.

thanks Dave. I don't suppose there were a lot of domestic vehicles produced in those years.

Parts are readily available for that transmission.