3 speed with overdrive

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Once in a while I get a bug and look at old vehicles that I know I will never buy. That disclaimer out of the way:

From what I can tell, the overdrive option for 3 speed manuals goes back to the 30's, and was somewhat popular in the 50's, and was available through the 60's. Not surprising, even with cheap gas, there have always been those who travel "a lot" per year.

What I don't get is the limitations of them: apparently they could roll away if left in gear, and they were known to freewheel the engine during coasting. I think... I'm not sure why, nor if that was always the case, nor if some judicious mods would fix those problems. I think there was a lever to disable OD and in which case it acted just like a standard 3MT. And I've read that there are some who have disabled the governor and use full manual control so as to split the gears (which is nice as OD was 30% and gearing splits in the trans was more like 60%), but what I don't know if full manual control defeats the freewheeling issue during cruise in 3rd/OD.

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[Yes, I know about the 833 4MT with OD that was used in the 70's and going into the 80's. But AFAIK none of them were 3 on a tree cool.
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Pulling the lever out of overdrive, which has to be done while the engine is pulling out of overdrive or the car is stopped,, makes the transmission like a normal manual with gear hold back. Putting into overdrive the handle can just be pushed in. Overdrive would be available around 30 mph and over, and you just let up on the gas and it drops in. Flooring the gas will downshift it out of overdrive.
Free wheeling was while in overdrive starting below the engage speed like 25 mph. Compression braking would just be up to that point then the OD would freewheel below that. Taken from memory. All the first cars I had had this setup, really liked it.
 
Ah, so freewheeling is only if OD is allowed to engage on its own, and below 25-30mph (give or take).
 
I take it (from the '62 Chevy manual, as well as Farnsworth's comments) that the car freewheels any time the overdrive control is not locked out, road speed is above ~25-30 mph, and the accelerator is released.
 
Originally Posted by ffhdriver
The free wheeling was hard on the battery because the generator was not charging at idle especially with lights on.
Probably the bigger complaint was accidents caused by idiots overheating brakes descending mountains with overdrive engaged, thus freewheeling.
 
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