The Stovebolt Site Forums The Shop Area Engine Shop T85N Borg Warner Manual 3 speed Overdrive Transmission

Hello/Greetings to all the truck guru's out there

I need information on the old 55-63 chevy Borg Warner electric overdrive transmissions(T85N)! They are great swaps because they are the exact length of the stock transmissions in the trucks of those years. I have run across several at swap meets, but have not bought one because I can't find anyplace that has parts for them, nor can I find anyone to work on them! HELP!

Everything you might want is probably here- Borg-Warner T85N

My recommendation is to get one and everything will take care of itself. These OD units are the best kept secret for the older trucks. I have built and installed dozens of them over the last 30 years. Parts are still available you just have to root them out. I just set one up this week using electrical components available from Napa.
Fred

This is my first post,I just purchased a 3 speed overdrive trans with a four prong carb switch, overdrive cable (it says it on the handle) minus the wiring harness and carb bracket for 300.00 U.S. dollars I intend on installing it on my 57 3100 chevy truck which has the original 235 with 3 on the tree. What needs to be done ?? will I have to shorten the drive shaft or how does it get current for the selinoid to work ?? Im totally clueless. I live in Southern Cal if there are any fellow stovebolters out here that can help me with the install i will galdly compensate them for their time. Thanks again for all the knowledge, I love this site , Ed

Ed,

If you have a T85N, it is the identical length as your original trans. No driveshaft problems. I can usually swap them in and out in less than an hour. The large post on the solenoid is your power, and the small one is the ground that runs over to the governor. It is supposed to ground the curcuit at about 27mph. I ground the governor because I only run the overdive on the highway and interstate, and that's where I spend most of my time. I don't use a harness, just a toggle switch. I have 35 inch tires on my 57 chevy and a 3.90 rear gear. I can run about 70mph at 1500rpm. I can almost afford to drive it now!!! Well at least I could before the planetary set came apart!! Thats why I was asking for help locating parts to fix it. It actually took round planetary gears a made them straight!! Bad transmission!! If I can figure the picture thing out, I'll show pics.

Oly has listed a great site about wiring and rebuilding the trans! Thanks!

I hope rfs56trk can come up with actuall shops that can get me some parts to fix this thing. I guess the other way to go is buy another one for parts, but my luck will have the planetary gears bad in it too!
Thanks for the info so far, guys!!
Brad

Welcome Ed. I got your E-mail on this tranny. The one in my truck was retro fitted, not factory. I beleive what you have is the SM318 w/the borg-Warner overdrive. This trans is a direct bolt in. I'd suggest that you use a premade wire harness to save the wireing headaches. The harness is being reproduced for the v8 models, but it will work fine with the 6. I also added a separate switch to shut the power off to it when not in use to save stress/wear on the electricals. I really can't give a feul milege for mine, as the engine isn't stock and my milege isn't real good to begin with. I can tell you that the o/d is a real joy on the open roads. I cruise at 75mph easily only turning about 1900 rpm. That's with a 30" tire and 3.90 rear gears. Some of the parts are hard to come by, but most of the primary trans parts are the same as the standard 3 speed. here is a link to the '55 manual showing how it hooks up. http://chevy.tocmp.com/1955truck2shop/55ctsm0715.htm

Longbox55 and 50tiger sorry for the late respones and thanks for all the info the more I read here the more I learn. I feel good about the buy and look forward to keeping all informed on my progress , hopefully I;ll learn how to post some pics to illistrate everything ,Thanks again guys, Ed

I put an o'd trans in a 1954 Chevy pickup, it was fantastic! It would cruise at 75 M.P.H. at 2000 R.P.M. the stock 235 never even strained. I installed it with one wire from a switch to the solenoid. It would go into o'd at a dead stop and worked smoothly. The trans was a direct bolt in, absolutely no problems, total installation time including wiring was 1 1/2 hrs. Do it, you will love it for sure.

Does any one know if those overdrive units will bolt up to a Saginaw 4 speed?
I talked to a guy that has a unit from a late 60's truck on a Saginaw 3 speed, any reason it wouldn't fit on the 4 speed as well?

Truckasaurus, two different animals, the earlier type is the Borg-Warner, the later type, the all-synchro Saginaw. People HAVE made a 4- speed overdrive from a Saginaw that I know of, don't know of anyone doing it from a Borg-Warner.... requires drilling an accurate hole in the 4-speed main case. It can be done. Search Inliners.org, or someone here might have done it.

Oh, and NO, a B-W tail shaft that includes the overdrive will not bolt up to a 3 or 4 speed Saginaw front main case, two slightly different animals with different bolt spacings.

Thanks Cosmo,
The unit is on a 3 speed Saginaw, is it a Saginaw overdrive?
I think the 3 speed and 4 speed Saginaws share the same tailhousings but was hoping someone would know for certain

I've got one of those 4 speed Saginaws with the O.D. unit on it. I didn't build it. I bought it from one of the guys on the Inliners site. Haven't installed it yet, but one of these days it will go into my '37 1/2 ton. Seems like I remember a write up somewhere on the Inliners site about building these. Maybe in TechTips? Prowl around over there and you will probably find it.

I ran one of the Borg Warner 3sp + O.D. for about 12 years in a '57 1/2 ton. It was a great setup. Like others have posted here, I just used a toggle switch on the dash to shift it. I didn't bother with the governor and kickdown switch monkey business. Who needs it? That's just over complicating things in my opinion.

I been running a Sagainaw 4 speed with an OD for a few years now,I did the build,farly easy.Ya need the OD unit from a Saginaw 3 spd,and the mainshaft from the OD tranny.3 and 4 spd Saginaws use the same mainshaft,but the OD shaft is shorter.3 and 4 sp tailhousing interchange,the cases are very similar,but 4 spd gearset reverse won't fit a 3 spd case.Comparing the 3spd OD and 4spd cases,drill one hole by hand,need to build up some weld on the reverse shifter fork so it acts on the a rod to knock the OD out when in reverse.
I've never seen a BW T85 tranny with OD in the common GM imput shaft and bolt pattern,typical Ford tranny.All GM OD's are the Muncie 318 or Saginaw to my understanding.GM did offer the non T85 as a 3 speed option in trucks years ago.
The OD unit from the earlier Muncie transmission looks similar,but won't fit on a Saginaw.

There needs to be a little clarification on the GM "Muncie" and "Saginaw" trannies. The SM318 is considered a saginaw trans, regardless of plant. The only true Muncies are the M20,21, and 22 4 speeds. Also, the 318 is not the same as the saginaw 4 speed, you're probably thinking of the 326 or 330 3 speeds, though all were made with the od option. The BW T85 was used in Jeeps as I recall, not GM. Possibly some Ford applications too.
As far as the od itself, BW manufactured the overdrive units for the different makes. Most of the internals are essentially the same. The mounting adapter is the primary difference.

There is a lot of confusion out there about what is a Muncie and what is a Saginaw. The Shop that I buy my 55-67 3 speed parts from calls that transmission a Muncie. It is Anaheim Gear in Anaheim, CA. They have probably built more of these gear boxes than we will ever see in a lifetime.
With regard to other 3 speeds in later vehicles, I am looking at page 7M-14/15 of the 1974 Chevrolet Passenger Car Service Manual which states: "Note: The 3-speed Muncie unit is similar to the 3-speed Saginaw design but differs in that it has a 3-1/4 inch center distance between the mainshaft and countershaft instead of 3 inches, and has larger bearings, gears, input shaft, and mainshaft. Power flow is essentially the same for both the Saginaw and Muncie transmissions" Also fig. 15-Muncie 3 speed - Transmission cross section.
I don't imagine this lessens the confusion any. Fred

There is a good article on the Warner T85 in the latest Hemmings Motor News.
It covers the overdrives as well and lists all the years, makes and models of cars you can find them in. One of the more common vehicles to find the OD in is the '65 to '71 Ford truck.

Fred, did I read in another post that you got parts from NAPA to replace the factory solenoid? This is the big drawback on these units since some people with a working solenoild want more for it than you can pick up a trans for. Thanks, Evan

Evan,
I use a Napa SL-199 Switch which is a late model GM cruise control switch and a AR-294 relay which is a 80's VW/Audi headlight relay. I use the original solenoid and govenor. I fabricate the carb/linkage bracket and make up factory type a wire loom using the correct color coded wires.
I have several of my OD's currently cruising the freeways in So Cal. If you would like to e-mail me direct I can give you additional info on the hook up. Fred

Lots of good info floating around out there! But other than Anaheim Gear in Anaheim, Ca., does anyone know of any shops that carry the sun and planatary gears - or any of the overdrive parts? If anyone in the southeast has an extra OD for sale, holler at me!

Thanks,
Brad