View Full Version : 2R5 Three on the tree VS Overdrive

01-23-2014, 09:17 PM
I am kind of new to this site and recently purchased a 2R5 1950 truck with the stock flat head and three on the tree. Right now I am just enjoying the truck but in the next year or so I would like to swap out the trans for one with overdrive. I know someone here knows what transmission is in this truck and what transmission is required to convert the truck to a three on the tree with overdrive. Is it a pretty straight forward conversion? and will the column shifter also need to be swapped out? Do I only need to acquire a transmission, I see a few T86 transmissions online but don't know what else is required, or if the T86 is the correct transmission. Also some of the T86 transmissions have different numbers included like T86E-1A. What exactly am I looking for? any help would be great.

01-23-2014, 09:48 PM
Go for it. The overdrive transforms the truck. It's really wrong Studebaker ever sold them without it. It's inexplicable why a buyer would ever take one without the OD.

Your shifter will work with an overdrive transmission, as all in front of the overdrive is the same.

You'll need the transmission complete with governor and solenoid, wiring harness, kickdown switch, control cable and driveshaft. Try to get it all from one truck, as it's much less expensive.

Be aware there are car and truck versions. The truck has lower first and second gears. That's only important if you plan to carry heavy loads.

There are also 6 volt and 12 volt versions. The solenoid is really the only difference.

jack vines.

01-24-2014, 01:51 AM
Champion 170 Engines in Trucks used a T-90 which is close to a T-86 but T-86's have V8 Input shafts and matching Gears.
T-86E's are Long Tail Transmissions with a slide in driveshaft yoke for Cars only, you need a fixed yoke for your two piece built-in slip joint Driveshaft. You will be having a Driveline Shop shorten your driveshaft, unless you find a Overdrive Front Shaft.

01-24-2014, 07:55 AM
You will have to shorten your driveshaft by about 9 inches if I remember right. Oh and by the wahy Rich a 2R5 does not have a 2 piece driveshaft.

Commander Eddie
01-24-2014, 08:24 AM
Sitting here reading this it suddenly occurred to me that I have an extra drive shaft for my '61 Champ. The truck should be on the same chassis but it has a V8. The transmission is a 3-speed with OD. Any chance this would fit mn1500s truck with the OD conversion?

01-24-2014, 08:38 AM
It should but the OD wiring and linkage would be different but that would make a great start for him

01-24-2014, 10:31 AM
Another facet to this is that postwar Studes - thru 1957 - used a relay on the firewall in the OD circuit. From '58 - on, the relay was eliminated and the OD solenoid was changed internally. You have to have the proper solenoid to go with a relay (and relevant wire harness) OR the proper solenoid (and harness) if you're going the "no relay" route. The transmission WILL NOT CARE which of these systems you use, so long as you use the correct pieces for a given setup.
IF you're gonna stay with six volts, you'll likely have no choice but to use a relay as 55 and earlier systems (which would all use a relay) were only 6 volt. 56 & 57 Studes (cars and trucks are the same OD pieces BTW) had a relay whereas 58 and later did away with the relay and used a different style of solenoid.

01-24-2014, 10:49 AM
Best bet is to find and use a T-90 OD transmission made for a truck. It will have the correct input shaft. An older T-86 car transmission can be made to work, but you have to shorten the input shaft, and reduce the diameter of the pilot portion. This is tough, because it's hard metal. You can't just put a T-90 input shaft into a T-86 because they have very different gears on the inside end. (Not that "slightly" different gears would work any better, heh.)

01-24-2014, 11:01 AM
Just because it's a T-86 O/D, you cannot assume it's from a Studebaker.

FoMoCo also used this trans: 1949/64 Ford/Merc Passenger Cars & 1953/64 F100's.

It was also used in misc Hudson/Nash/Kaiser/Frazer/Willys and etc.

btw: The 6V O/D relay is reproduced by Studebakers West (it's the same as 1949/55 Ford). Dunno if they also repro the 12V relay.

01-24-2014, 06:50 PM
Wow, thanks but that's a lot of information. If I read all the posts correct is seems like the easiest way is to find the original T90 overdrive transmission from a pre 55 truck as mine is still 6volts. But along with the transmission I will also need the governor, solenoid, wiring harness, kickdown switch, control cable, drive shaft will need to be cut down with the T90 and shortened and converted to a input type front shaft if I use a T86, and lastly I will require a 6 volt relay which is mounted on the fire wall, or I can purchase this at Studebakers West.
Does anyone have pictures of these parts?
If the relay is on the firewall is the governor, solenoid, kickdown switch, and control cable mounted on the transmission?
Is the wiring harness between the transmission and somewhere or is it a complete new truck wiring harness?
This seems like quite a project if you have never done it before since there are so many electrical parts. I have changed a manual transmission in the past but it did not entail electronic parts. Since the shift lever does not need to be changed and the overdrive seems to be electronically controlled how do you shift into OD do you push a button? How easy is it to find a T90 from a 55 or older truck? are they around or all snatched up and real expensive? Is the T86 easier to find and less expensive?

I appreciate all the help and gather way to much information before I take on something like this so any help would be great.


01-24-2014, 07:09 PM
I've got a 3 sp od out of a 58 sliver hawk flat head 6 cyl. would this work for what he wants to do?

01-24-2014, 07:48 PM
I've got a 3 sp od out of a 58 sliver hawk flat head 6 cyl. would this work for what he wants to do?

Yes, it would work, but the '58 is a long tailshaft T96 tranny.

No, it's not what he wants to do.

Maybe, buy a Shop Manual and all will be explained. As mentioned, try to find a parts truck with tranny, controls and driveshaft. Much less hassle, less confusing.

Maybe also, this should be moved to Tech Talk.

Maybe again, the OP should go over to Studebaker Truck Farmers and post a WTB. Someone there is sure to have a complete T90 setup. http://www.network54.com/Forum/23885/

jack vines

01-24-2014, 07:50 PM
mn1500 , don't despair , this is not that hard a job , I did this very thing to a 1950 2R5 back about 15 years ago .
I would recommend you buying ( if you don't have one ) a parts catelog for your truck , study all the differences and even try to find someone who has a truck equipped like you want to do .This all will help you understand the differences and your job ahead of you.

01-24-2014, 07:51 PM
I also have a O/D from a 52 Champion, If that will work???

01-24-2014, 07:54 PM
... find the original T90 overdrive transmission from a pre 55 truck as mine is still 6volts. But along with the transmission I will also need the governor, solenoid, Find that transmission and the governor and solenoid should be included.

01-25-2014, 09:23 AM
Any recommendations for a good shop manual or parts catalog? And where to buy? Thanks for all the comments.

02-14-2014, 07:19 PM
Well I purchased a Studebaker truck parts catalog and found a donor truck. The truck is in real bad shape with most of the parts missing and a damaged frame. It does have a complete overdrive transmission, pull cable in dash to transmission, driveshaft, solenoid, governor, most of the wiring is cut and not complete between the electrical parts. The relay on the cowl is missing and I forgot to see if the kick down mechanism and electrical parts were there, I just missed looking for it. I cannot see the part number on the transmission (T90 or T86) but it is bolted to a flathead motor in what the seller is calling a 51 Studebaker 1/2 ton, and it looks like a 51. I guess my question is, I see the relay that mounts on the cowl is available for about $65 + tax and shipping what about the kick down mechanism, bracket, and switch? Are they available and if so do you know how much they cost? Then if I get all the parts is there a wiring diagram available to show how all the parts are wired together? The seller is asking $450 for transmission and driveshaft, without the bell housing or anything inside the bell housing, not sure if that is a good price for a transmission in unknown condition. Any help or advice would be great.