The Stovebolt Site Forums The Shop Area Driveline speedometer gear difference?

I have a 58 3100 and recently replaced my standard 3 speed with an overdrive unit. My speedometer does not work now. Is there a difference between the two speedometer gears. The overdrive gear was missing so I used the one from the standard 3 speed.

there may be a ratio difference because the OD came with a 4.11 rear rather than 3.90, but shouldn't be a difference to prevent turning ... the fact that it was missing may mean someone else had a problem someplace further inside ... are you sure you got the cable back on properly engaged at both ends?

Bill

It was never removed at the instrument cluster only at the transmission. After it did not turn while driving I found after removing the overdrive speedometer gear housing there was no gear inside. I then replaced the entire assembly with the complete assembly from the original three speed and it still does not turn.Does the overdrive lever have to be engaged when the gear is installed?

the procedure in the shop manual is the same for both transmissions

Bill

The 3 speed speedometer drive gear and some early driven gears will not work on an OD trans. The OD uses a wider gear as it also runs the governor. If your original 3 speed trans used the steel driven gear it will not work with the OD spedo drive gear. You will need to get the correct OD drive gear and a plastic driven gear.
I think I'm using a 22 tooth driven gear for the 3:90 rear end.
Fred