The Stovebolt Site Forums The Shop Area Driveline adding overdrive transmission to a 1951 3100

I am looking to update my 3100 pickup with an overdrive transmission to improve drive ability / top end speed while maintaining period experience. The truck has a rebuilt 235 engine with the standard three on the tree transmission, closed driveshaft and rear axle. I have purchased an overdrive transmission but need the driveshaft and rear axle updates to complete the project. Could use advice / direction on parts I need and possible where to get them. Thanks in advance for your help.

What OD trans did you get? Driveshafts are usually made up when the trans. has been installed, by dimension from the trans. and diff. Do you have a torque tube rear axle setup? That would be the only reason to fool with the rear axle upon installing an OD trans.

Ed

As I'm sure you're aware, there were very few OD options that allowed the use of the torque tube rear end, and the ones that did exist are scarce beyond belief. For instance, the Truxtell "Tip-Toe-Matic" system replaced the torque tube with a shorter item and put the planetary gearset at the rear of the original transmission. You'll need to acquire a later model open driveline rear axle, and also change the pivoting rear spring mounts for solid ones, with the right pinion gear angle built in as you weld the spring perches onto the axle housing. Don't get tempted to go with a very high ratio rear axle- - - - -Something in the 3.50-3.70:1 ring and pinion ratio will work well with the OD- - - -higher gears will have you shifting in and out of OD too frequently unless the area where you drive is as flat as a pool table. Also, don't get caught up in the fallacy that "all you need is a toggle switch" to make the OD work- - - - -wire the system up properly with a relay and a kickdown switch, using the original Borg-Warner wiring diagram. A Bosch-type relay and a double pole single throw microswitch will substitute for the scarce and expensive OEM parts and work just like the originals.
Jerry

If you decide to do an Internet search: the correct spelling is TRUCKSTELL

It is my understanding that you can use it with an enclosed drive-shaft, but you have to cut the torque-tube?Documentation/illustrations are available from that Google search

There was a Tip-Toe-Matic version that (I think) allowed engagement and disengagement using a complex set of foot-controlled levers/cables/etc. This assembly can supposedly be adapted to work in a truck?

I have an assembly in my storage shed - a Stovebolt member has "dibs" on it.

To improve drive ability / top end speed and maintaining period experience.
You would be better off keeping your 3 speed tranny and swapping out the 4.11 ring & pinion rear end with a 3.55 ring & pinion.
The 3.55 ring & pinion gear set will let you cruise at 65-70 mpg. But you need good brakes.

Check out speedometer in photo, is a says 0 10 20 30 40 50 60 PRAY.

xfiles

I agree with jorb.

That is what I have in my Suburban (and, wider-diameter truck-radial tires on original 1954 3100 wheels).

That lowers the RPM by 15%.

If you also use the installation kit, all bearings/bushings/seals will be new. My drive-line/interior is much quieter.

jorb said it all. Be sure to have better brakes when you increase your cruizin speed.

Even if you convert to a T5 (which can be made to look almost exactly like the original 4 speed), there will be plenty of "period experience" left for you. As others have said (and it really can't be stressed enough), make certain your brakes are very good. Also your front end...as I'm certain you already know, pretty much nothing about these trucks was designed for today's freeway speeds.

Eight days of no response from the OP.
You boys scared the new guy away after his very first post!

I think the OP is a very busy person.

He joined in 2014. So, maybe he is not a new guy.
First and only post is the first post in this thread.

Stovebolt is not one of his/her priorities.🛠

Maybe not, but he sure did give a bunch of us, with nothing better to do, the opportunity to opine.
Maybe he'll get back to us in another six years.

The OP wrote “I have purchased an overdrive transmission“, though he didn’t give any details about it. His knowledge level of his truck including the torque tube may be... limited. For a long time I didn’t really understand them either. Hopefully he’s reading and learning from here and other sources.

Hi guys. Sorry for the delay getting back and thanks for all the informative comments.

As with many this past year was full of challenges that pushed the truck down the list of things to take care of. Well we're back on steady ground and looking to get things running with my 3100.

To answer some of the questions I have replaced the torque tube driveline with an open rear axle from a 1955 3100. I adapted it to the original leaf springs to get the correct ride height and wheelbase. I replaced the original 3 speed transmission with an gm overdrive transmission from that period. Looks similar to the original trans but has a solenoid and cable that run to it to control from the driver seat I don't plan on installing the full automated system but use the cable to engage / disengage the overdrive.

The last part of the set up is getting a drive shaft to tie it all together. The tail shaft on the trans is 16 spline. Need to find a source for the new driveshaft. Any thoughts?
I hear the discussion on the front chassis and brakes. The original have worked fine previously, but I think an update from the single master cylinder would be a good modification along with the roller bearings instead of the ball bearings.

Look forward to the next round of advice. Thanks in advance.

There should be any number of driveshaft makers up your way. I'd try to look closer to home to minimize shipping costs. If you need help on measuring for a new one, please let us know. Not difficult at all.

Jon G Your right better not push it on speed in AD trucks. My 51 6400 is happy at about 48 MPH !!

Mr Masseyman You'll learn this,with the overdrive in the truck can roll away. Best to park in reverse which will take it out of overdrive !! I also put my kickdown on the dash ,so I didn't have to throw the throttle wide-open to downshift.

55-57 Passenger cars and 3100 TF trucks with a 3 speed or OD trans use the same driveshaft. I believe the earlier models like your truck have the same wheelbase. If so, find one for those years and you don't have to make one up.

Fred

With this OD and no power to the little motor mounted to the side of the
transmission, can the OD be operated manual at 45mph +with the pull cable?

No- - - -the cable can only lock the transmission OUT of OD, like for going down Wolf Creek Pass!



Jerry

I found a driveshaft site online called Denny's Driveshaft. They sell a 16 spline yoke but can't build a driveshaft with that because they can't balance it with that 16 spline yoke.

I used their diagram B for measuring. https://www.dennysdriveshaft.com/app/webroot/img/File/how_to_measure_diagrams/b.html

#B6 came in at 56.625"
#B7 = .375"
#B10 = 3.129
#B11 = 1.062

If this sounds the same as a production shaft that would be good. Could use help finding a driveshaft. Let me know if you have some good suppliers.

Thanks again.

Overdrive transmissions operate best when they are installed with the electrical components as the factory intended.
Fred

I find they operate just fine when simplified in some cases. Just use the governor and wire it through either a manual switch or one under pedal or micro on throttle linkage for auto pass gear. Use a bosch 5 pin standard 30a relay to throw the solenoid. I love mine. I have a manual pass gear on mine but with the v8 i never have to really use it. It auto downshifts from governor under like 25mph anyways.

mm

Mr Masseyman My first 53 3100 had a57 car rear axle,51 car 5 lug front hubs,used a tri-5 overdrive with a homemade welded in the middle driveshaft. Ran the rheels off of that one.Had my kickdown switch on the dash so you didn't have to open 2 four barrels to downshift ! I later learned that if the driveshaft is stralght it is balanced.Now you might fine tune it but in our 3100 trucks probably fine !! Have made several since that. We did balance some with a strobe light wheel balancer and hose clamps.

barnfind Did you know you can put the saginaw O.D.on the 4-speed ?? Done that in early 70's worked fine !!

rfs56trk Do you know of a source for Delco relays ?? Have used ice cube relays for thatbut a real Delco would be the best ! Nice to have one in the glove box !!!

fixite7,
There are some original Delco relays available on ebay. A 55/56 that uses the ring terminals for about $175 and a 57 up that uses spade terminals for about $120. I use the Bosch type relays in the wiring kits that I provide with rebuilt overdrive units. They work fine and most people don't want to spend that much for a relay. Similar story with KD switches, the Ford switches are reproduced and are about $30, NOS Delco switches are $200.
Fred

Yea I have seen it done. I contemplated doin one on a car I had with a 4 speed previously but knew it wouldn’t take much abuse.

To the OP, check this out, it's a PDF download.BW OD https://www.google.com/url?q=http://www.potomacbird.com/pctc/Public_Documents/bwwiring.pdf&sa=U&ved=2ahUKEwiJ_5e0xqPxAhWOt54KHbATDCcQFjABegQICxAB&usg=AOvVaw2bQMnK2vpR-hicGvyMfpdG

This is how I have my T85/R10 set up in my 49 3600. It works awesome!! I have full control of how and when it shifts, or I can let it just do it's thing

Im not sure if that link is working properly. I can email the PDF, just shoot me a message

Like someone state, "I run about 48 mph." I put a license plate frame on my 59 3100 that says, "Retired, now go ahead and pass me!"

This is how mines setup.