The Stovebolt Site Forums The Shop Area Driveline 3 speed trans compared to 3 speed with o,d,

What is the difference in gearing between my original 3 speed tranny in my 50 3100 and a later model 3 speed with overdrive? Like a 58 3 speed with od? Would it be like a 4 speed with a 4th gear being overdrive? how much increase in highway speed do you get with this overdrive? Does a 58 3 speed with od use a torque tube set up or standard open driveshaft configuration? Just trying yo gain some knowledge.

Heres some good reading on the OD unit.

Dave

While your 50 3 speed trans may have similar gear ratios, little else is the same as the 58 OD transmission. 55 up vehicles do not use a torque tube, all are open driveline. The BW OD replaces the tail shaft on a standard 3 speed transmission. It has an electric solenoid, other electrical components, and a cable to engage the system. There are some later 4 speed transmissions that 4th gear is an overdrive. They are completely different from the BW unit. This and most OD units are 70% overdrive. They will lower engine rpm's and can increase speed accordingly.
You should consider that early vehicles were designed to drive at lower speeds and the brakes and steering were designed accordingly.
Fred