I have a '41 one ton with the 4 speed heavy duty tranny. I'm considering looking up one of the 5 speed kits for this thing, but I don't want to get one if this is good enough. The truck has an open drive so converting that part is no problem, and I don't mind "double clutching" as I heard people call it. The thing won't be driven all the time, but I still want something that will be good for stop and go traffic and at least be able to get up to 70mph without too high of an rpm. The rear gear will be changed, but before I'm set on that I'm going to paly around with some numbers.

So, can anyone tell me the ratios of each of the gears? And would this be ok for this purpose?

And while I'm at it I might as well ask for the ratios of two trannys sitting around in my yard, they are both 3-speeds for an 8ba. One is a column shift and the other is a top loader (don't think that is much help). Thanks!

Clayton

 

Clayt
This info is only general in accuracy but should give you a close guess. The 8BA car trannies will be close in ratio to the light truck tranny.

In the trucks (top loader and column shift were very similar),
1st gear is around 2.8:1
2nd gear is around 1.60:1 and of course
3rd is 1:1. Reverse is 3.63:1

Since Henry didn't change things much, my gear info for the 48-52's should also be fairly close.

The 4spd trannies in the one tons - all spur gears - were as follows:
1st gear 6.4:1
2nd gear 3.09:1
3rd gear 1.69:1
4th gear 1:1
Reverse 7.82:1

The rearend will be a greater limiting factor. Again, 48-52 one tons had rear ratios of 5.83 and 5.14. If you have a tag on the differential look for 35/6 or 36/7.

With a 1:1 final tranny drive my 48 F1 is turning about 2500 rpms at 65 mph with a 3.50 rear end. If you do have a 5.++ setup plan on top speed of about 50 or lower unless you change third members.