Gear shift box location on the floor

[MishaZ]

Hello all. Just purchased a 1951 3100. I’m going through all that is on the truck right now and evaluating what work needs to be done. Full disclosure, this is my first time working on this type of truck and all advise is welcome.

As I was looking at the gear shift box location on the floor, I was wondering how do others look like. Did these all come 3 on the tree from factory and the floor location is a conversion? Looking at the plate that is on the floor, the stick opening is in the different location then where the lever is coming out from the box. New opening appears to have been cut.

 

[Bill Hanlon]

In 1951 (and at least 1946 through 1990) 3 speed manual transmissions came from the GM factory with column shifters and 4 speed manual transmissions had floor shifters. The floor shifter shown in your picture is an aftermarket part. The plate on your floor is designed for a factory SM-420 4 speed where the shifter comes out of the top of the transmission through the factory hole on the upward bulge in the plate. The factory 3 speed plate had no holes, except for the hold-down screws. Someone cut the plate you have to allow use with the aftermarket shifter.

 

[MishaZ]

Thanks Bill. Looks like I have a conversion kit.

can anyone recommend a gear shifter that has a female threaded connection at the bottom? Attaching a picture of what I mean. What is there now appears to be a mod job.

 

[Bill Hanlon]

Other than being uglier than me, what is wrong with what you have now?

 

[MishaZ]

Bill, here are my issues with it and perhaps there is a workaround for them. One, the top of the shifter is not threaded and am unable to add a knob on it. Second and more important, I can't tighten the shifter in a specific orientation, as it's just a nut that is welded to the end of the rod. Third, it's a bit short.

 

[MishaZ]

Anyone?

 

[Bill Hanlon]

The shift lever you have now looks to me like a home-brew to me. The shaft appears to be one diameter, instead of tapered like a factory shaft would be. The lack of threads on the top and the lack of ability to clock the bottom of the shaft to the proper position are the problems to be overcome. Unless you are willing to scrap the whole shifting system and start over, the male threaded piece that the shift lever threads onto will need to stay in place.

If you could find a set of shims (washers) with an outside diameter that would allow them to fit inside the nut on the bottom of the lever and an inside diameter that would fit over the the threaded male piece you could experiment with adding shims until the lever was clocked where you want it to me. Shims can be found at Fastenal or McMaster-Carr.

A poor man's version of this fix might be to wad up some aluminum foil into the nut on the bottom of the shift lever and tighten the lever down observing its clock position. Then adding a bit more foil until you get it right. Don't put more foil (or real shims) in than making the lever one full turn less than it would be without the foil (or shims) in place. Don't want to weaken the connection.

 

[MishaZ]

Are there shifters out there that are real deal that I can purchase that would fit over a threaded connector on the floor and are able to be locked in place?

 

[Bill Hanlon]

Are there shifters out there that are real deal that I can purchase that would fit over a threaded connector on the floor and are able to be locked in place?

Not unless:
a. you can identify the current shifter's make and model
b. the company is still in business, still making the parts and would sell them to you

I am far from an expert on '51 Chevy truck transmissions, but if it were me I would do one of the following.

c. Find a complete floor shifter that would work with your transmission. I THINK your transmission is the same as used in '51 Chevy cars which may help in your search.
d. Cut of and use the bottom couple of inches of the current shift lever.
1. Thread the top of the now very short shift lever at least an inch long.
2. Put a regular nut on the newly threaded area.
3. Thread the short shift lever onto the shifter mechanism.
4. Weld a shift lever* to the coupling nut.
5. Turn the coupling nut/shift lever onto the newly threaded short shift lever, locking it in place with the regular nut.

* I'd use a cut off shift lever from a SM-420 GM 4 speed transmission

 

[vwnate1]

This MAY be an old T-10 shifter, maybe look them up on google images and if the same go from there .

Clearly your shift lever is a home brew job, nothing wrong with that but I see why you want to improve it .

 

[e015475]

IMG_0260

• e015475
• Nov 1, 2025

My truck has a T5 transmission with a Johnny Law shift lever. I don't much care for their products, but it was the only one I could find.

Shifter Arms & Accessories | Shifter Accessories | Transmission & Shifters | Johnny Law Motors

These shift levers screw into a female thread on the shift mechanism and the nut threads down to lock it in place- same as you show in your picture

Shifter

• e015475
• Feb 1, 2020

IIRC I welded a coupling nut to the shifter extension provided with the shifter for the Johnny Law lever to screw into.

The chrome bezel and the shift boot are from a b-body Mopar.

 

[Chiro]

Pretty cool mod to get rid of the column shift mechanism which has been the source of many problem posts here (jamming column mount shift box requiring rebuild with sketchy reproduction parts and much colorful language). This is what hod-rodding is all about. Problems like your shift lever require many adult beverages and contemplation all while sitting in the driving seat and making "vroom-vroom" sounds. Looks like shims to get the correct position and turning down and threading the shift knob end would be a good solution, as per Bill. A talented welder can easily add length to your shift lever as well. Is there room enough to put a jam nut under the bottom of the shift lever to lock the position? McMaster-Carr (website) has very thin, half thickness nuts that may work for that application. Warning!!!...the McMaster-Carr website is VERY addictive for gearheads! You have been warned.
Andy