The Stovebolt Site Forums The Shop Area Engine Shop Overdrive on 3-Speed

I had an interesting conversation with a neighbor this weekend. He was telling me that there's an electric overdrive unit that will bolt onto any transmittion to add overdrive. It seems a little far-fetched to me but I thought I'd check with you guys. If it's legit, tell me more about these. Thanks.

He may have been talking about the Gear Vendors unit. They have units for lots of applications. It's a planetary gear unit that replaces the tailshaft on the tranny.

Hey Xram, i went to the Gear VEndors website and I couldn't find the overdrive for the 3 speed manual, but i could for the 3 speed auto. Can you point me in the right direction, thnxs

Maybe your thinking about the old Borg Warner R10H electric overdrive that came attached to the Muncie and Saginaw 3 speeds?

Gear Vendors doesn't seem to list a unit specifically for a 3-speed manual on their site. However, they do say, "should you not find your specific vehicle listed...rest assured that we can provide a unit which is designed for your application. Just e-mail us today or should you wish to talk to one of our application engineers just call 1-800-999-9555."

The big drawback to the Gear Vendors units is $$$$$$$$$. In many cases, it would probably be cheaper to swap in an overdrive tranny.

There was a unit made by Truckstell that gives you a overdrive on a 3-speed. I´m looking for this since years because it lets you keep the torque tube and all the rest of the rearend. But they kind of super rare.

Yes, Gearvendors does make an electrically operated overdrive for the SM420 and SM465 transmissions. It is a planetary gear system and can handle up to about 1400 lb-ft of torque. Shifting is activated by pressing a button and will go into overdrive in any gear. My understanding is it's very high quality and works very well. Expensive though. Currently about $2700. The price is going up faster than what I can afford. But maybe someday.

Check this out:

http://www.classictruckshop.com/clubs/earlyburbs/projects/over/drive.htm

It won't bolt on to just ANY 3 speed tranny, but these were used on a lot of Chevies in the fifties and sixties.

on the gear vendors site they mention that they do make overdrives for the enclosed drivelines. i think it was in the classic or maybe the antique section, if my feeble brain recalls correctly.