# Gibson Model D Four Speed Transmission Question



## mslisaj (Jan 20, 2017)

I am restoring this Model D Gibson and I was informed that the four speed transmission that is in my tractor was an option and pretty rare. I would really like to disassemble this transmission for cleaning and inspection but I would love to get a "small parts kit" and a gasket set before I tear it down. My question is everyone knows the make and model of the usual three speed but what is the make and model of this four speed? Are parts and small parts kits available for this? Any information on this box would be helpful.

Thank you for your time to read and respond to my post here.

Lisa


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## willys55 (Oct 13, 2016)

Welcome to Tractor Forum.

Is the transmission giving issue? Why tear it down?


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## mslisaj (Jan 20, 2017)

Hi Russ,
Well the tractor has been stored outside for a long time. Rainwater has seeped into the trans through the tower and has frozen the shift rails. I pulled the cover for inspection and I could see the oil was "milky" and the gears had some substantial rust. The first gear had been beat up pretty badly but appeared to have all the teeth. On this first inspection I could not drain the transmission as I hadn't purchased the tractor yet and it was the pre-purchase inspection. But now that I own the machine I need to get it back to the shop and I was thinking I could pull this transmission out and disassemble it for a thorough cleaning and inspection. BUT, I don't know anything about the transmission like make and model and who made it. A lot of old four speeds were made forever and parts are available. If I can't get any info on this I will just drain it, clean it out the best I can and put in fresh gear oil and run it for awhile and then drain it again. But I am going to disassemble the tractor for cleaning and painting anyway so I am just trying to line up the parts I may need. 

The rear brakes have been removed also with one brake drum. I am lucky to have received all the brake parts except the rods and bands. But I got the pedals and actuators, the brake drum, the rods can be made and the bands purchased in reproduction. But I have to take that apart too for repair. 

Thanks for taking your time to respond Russ,

Regards,

Lisa


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## willys55 (Oct 13, 2016)

as you move along in the repair, post up pictures...we love photos


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## mslisaj (Jan 20, 2017)

Well I don't have the tractor home yet but I have brought home a truckload of spare parts. Here are a couple of pic's...........


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## mslisaj (Jan 20, 2017)

Apparently only one picture made the trip. Here is another view and I promise a better picture when I get the tractor home.
Thanks for your support.

Lisa


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## RC Wells (Dec 26, 2008)

The transmission in your Gibson is essentially the same four speed that was found in Ford and Chevy pickup trucks of the era.

If the bearings are not pitted and it rolls over easily without any dragging, I would Just drain it, flush it, clean the shift rails, and put in fresh oil and it will last forever. That transmission is way under-stressed in the Gibson. A tube of RTV will take care of any making any gaskets needed. If a bearing is bad it will feel rough, then pull it and take it to a bearing supply shop, they can match you up with a current bearing.

As for the rubber boot on the shift lever leaking rain, one from a Jeep with the Borg Warner T-96 should fit the four speed tower. 

The 1946 Gibson Model D has 22-inch rear tires on Ford rims, a Chevrolet truck transmission, and a Chrysler differential/axles. Both the three speed and the four speed were from Chevrolet.

The 1947 Gibson Model D has 24-inch rear tires on International-Harvester Cub rims, a Borg-Warner T-96 three speed transmission, and a Chrysler differential/axles.

Later Gibson's were sometimes fitted with the Ford four speed from WWII military staff cars, and that is pretty much the same transmission Ford used in the 40's and 50's pickups. That basic transmission was still in use up through the late 70's.

It was very common for owners to swap out the three speed transmissions to four speed light truck transmissions to get a compound low gear for pulling heavy loads. So, it is possible you may have one of those.


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## mslisaj (Jan 20, 2017)

Thank you Mr. Wells for your detailed reply. I have a 58 Chevy with a four speed and in my mind that transmission looks bigger but then again it may not be; also this transmission has a reverse lockout. The big difference is this transmission is unsynchronized in ALL the gears. I agree with your idea if it works leave it alone. I'm into RTV also. I think my plan of attack for this machine will be when I get it home first thing will be drain and flush the transmission. Fill it with fresh 90W and free up the shift rails. Next I will get the engine started. If all this goes as planned I will drive the tractor around and through all the gears. If this checks out good then I will completely disassemble the tractor for clean up and paint. I'll disassemble the rear end far enough to reinstall the missing brake drum, purchase new reproduction brake bands and then put the rear end back together with fresh oil and new brakes. I think then I will have a pretty functional tractor for show or occasionally pushing snow. The rubber boot for the shifter tower won't be an issue as probably the first time in this tractors life it will be kept indoors and retired. I'm attaching a picture of the transmission that shows the abbreviated tail shaft. Weird. But I think (hope) it will be a fun and simple project.

Thanks again for taking your time to reply.

Best regards,

Lisa


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## herbertpogue (8 mo ago)

RC Wells said:


> The transmission in your Gibson is essentially the same four speed that was found in Ford and Chevy pickup trucks of the era.
> 
> If the bearings are not pitted and it rolls over easily without any dragging, I would Just drain it, flush it, clean the shift rails, and put in fresh oil and it will last forever. That transmission is way under-stressed in the Gibson. A tube of RTV will take care of any making any gaskets needed. If a bearing is bad it will feel rough, then pull it and take it to a bearing supply shop, they can match you up with a current bearing.
> 
> ...


I have a 3 speed but it doesn't look like the t-96 here are a few pictures could you help me identify it?


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