The Stovebolt Site Forums The Shop Area Engine Shop '65 3sp w/OD

Hi,

My father had a 1965 Chevy pickup with a 3-speed transmission. It had an overdrive behind it and came that way from the factory. I seem to remember the OD being a separate box, but that was a long time ago and I probably didn't pay that much attention to it at the time. Was this a Muncie unit, Borg-Warner or something else?

Thanks,

gary

if factory it was a BW T85 overdrive unit that replaced the rear section of either the Muncie or Saginaw 3spd, not a seperate box

Bill

Bill, not trying to rock the boat on you, but
I don't think the Warner T85 was used in Chevrolets as original factory equipment.
I believe Ford and AMC were the only manufacturers to add an overdrive to the T85, which I think was called the T85N. The most common trucks to find the OD unit in were the '65 to '71 Ford trucks. I found one in a '67 or so Ford at the junkyard, but when I went back to pull it out it was gone!
There was a good article on this transmission in Hemmings a few months ago...I'll try to find it.

rider, my boat don't rock, well anchored by 3 original GM factory BW-OD trannys, did you look at that link? it has a companion about wiring here - never heard'em called anything else, and the shop manual doesn't give the OD a name

maybe the actual OD unit part aren't T85N's, but that's what we've been callin the trannys here for years - don't know if Ford used BW too

Bill

I think Ford, AMC & GM used the same unit, IIRC. Seems like I got a big old early 70's MOTOR manual that lists the T85 as going into Jeeps, Fords, Chevys etc. Brian

I have been looking for an OD transmission for my 3/4 ton that I plan to use for working. I have a 3 speed OD trans out of a 55 chevy car, (are factory truck OD's different?)but someone told me a T85 would be a better choice as it was a bit more heavy duty. So I did some research on it and was surprised to find out they didn't come in Chevrolets, according to one source anyway. Here is a link to the Hemmings article
It won't show you the whole thing if you're not a suscriber, but it has a little info. I have the hard copy around somewhere. I have a T5 I was tempted to use, but will save it for the next 1/2 ton I put together.

anyone a subscriber?i have one of those and wonder what it says.

Ghostrider,
The 55 car transmission will work fine in your 3/4 ton truck. There is no difference internally between a car and truck trans (55 to 65). The lower mount holes are not threaded on the car trans and the shift arms & side cover are different on some years. I used this early trans/OD combo in a 66 3/4 ton for 15 years and have one in my current 56 with a 350 engine. The later (66-70) Saginaw OD's are probably a little more heavy duty and 1st gear is a syncro. Also the BW OD was used in Fords, Studebakers, Packards, and just about everything else. Many of the internal parts are the same, planetary sets, roller clutches, etc. The differences are the items that are specific to the manufacturer. Fred

Fred,
Thanks for that info. One of the things I didn't like about the '55 OD trans is that the input shaft diameter is smaller than my original 3 spd input shaft. (after the splined section)
Take a look here.
It's probably nothing to worry about, though I do plan to use this truck for it's original intended purpose. Anybody have any input (no pun intended)
on this?

rider, that input shaft is what's on all the truck OD's I've seen ... I suspect the car and truck OD is the same

Bill

Thanks Bill,
I was flippin through my 1957 Motor's truck manual
and they show the standard '55-'57 3 speed as having the same input shaft that's on my OD.
The heavy duty 3 speed does have the larger input shaft however. If I did use the OD I would have to use a manual operated solenoid cable/lever like the one OverDrive Inc. sells because I don't plan on converting to 12 volt anytime soon.

Ghostrider,
In my collection of OD transmissions and regular 3 speeds, some have the small shaft like the one on your OD and some have a solid shaft like the earlier AD trans in your picture. I'm not sure why there is a difference but both will work equally well. I have probably rebuilt 50 of these transmissions and have never seen anyone break the clutch gear. This basic transmission was the standard bearer for the early Corvette (with a 2:20 first gear and steel syncro rings) before the 4 speed became popular. Pontiac also used it 57-58 with a bigger set of gears. They hold up ok if you understand their limitations. Fred