1918 (1917 ??) MODEL TT TRUCK REAR END IDENTIFIED EARLY DIFFERENCES

[StevenS]

I would like to open this up for discussion (please add what you have found out on Model TT rear ends). In repairing my Model TT Truck, I collected 7 other rear ends for parts to use in the repairs. One of the rear ends was an early one (year 1918). Through the research on the MTFCA website on all the posted discussions, I could find, I was able to make a list and cross-referenced it with other opinions on the differences and believed ages of the rear end I found.

While trying to date the rear end, what I did find for dating a Model TT rear end was that the Model TT Truck were made from 1918 to 1927, but also there were some Model TT Trucks made after 1927. Also, some believe the Model TT Truck was made in 1917, but a corroding to the records those were 4 prototypes. So, my opinion there are really no 1917 Model TT Trucks that would have been sold to the public. So, the 1917 Model TT Truck would have not really have been out there (Ford would have not sold them). So now looking at the rear end I have, here is a list of the differences of this rear end:

First, there are the ridge beads that run around the outer edge of the casted gear housing (pumpkin). Where the casting meets the straight axle housing pipe.

Second, the rear worm gear cover cap does not have an oil filler plug. Real early trait.

Third, the bolts from the rear worm gear cover cap does not go through the casted gear housing (pumpkin). The casted gear housing (pumpkin) does not have the hole going all the way through the casting.

Fourth, there are a set of matched numbers stamped on each half on the top of the casted gear housing (pumpkin) at the end where the rear worm gear cover cap is. This has brought up an interesting discussion in other talks on this website. Those numbers show up on early rear ends and those numbers that other people have are not the same (so it is not a part number). So, looking and reading what has been collected, I would speculate that those number are serial numbers on the early rear ends (which that practice was stopped in 1918/1919 sometime). Maybe it was on only the 40,000 that were produced in 1918 where most of those Model TT Trucks were sold to the military. Or those numbers were to match the left and right halves during the machining and production of the early rear ends. I am not totally sure what they were for.

Fifth, the brake plate is also attached with a rivet to the rear end. Look at the bottom at the rear end where the axel comes out and the brake plate attaches and there is an extra cast piece with a rivet.

Sixth, the radius rods ends where they attach to the torque tube are larger.

Seventh, in the internals there is only a two-gear spider.

Eighth, in the internals the drive shaft end splined grooves are shallower as well as the grooves in the coupling.



First, there are the ridge beads that run around the outer edge of the casted gear housing (pumpkin). Where the casting meets the straight axle housing pipe.

Second, the rear worm gear cover cap does not have an oil filler plug. Real early trait.

[StevenS]

Third, the bolts from the rear worm gear cover cap does not go through the casted gear housing (pumpkin). The casted gear housing (pumpkin) does not have the hole going all the way through the casting.

Fourth, there are a set of matched numbers stamped on each half on the top of the casted gear housing (pumpkin) at the end where the rear worm gear cover cap is. This has brought up an interesting discussion in other talks on this website. Those numbers show up on early rear ends and those numbers that other people have are not the same (so it is not a part number). So, looking and reading what has been collected, I would speculate that those number are serial numbers on the early rear ends (which that practice was stopped in 1918/1919 sometime). Maybe it was on only the 40,000 that were produced in 1918 where most of those Model TT Trucks were sold to the military. Or those numbers were to match the left and right halves during the machining and production of the early rear ends. I am not totally sure what they were for.

Fifth, the brake plate is also attached with a rivet to the rear end. Look at the bottom at the rear end where the axel comes out and the brake plate attaches and there is an extra cast piece with a rivet.

Sixth, the radius rods ends where they attach to the torque tube are larger.

[StevenS]

Seventh, in the internals there is only a two-gear spider.

Eighth, in the internals the drive shaft end splined grooves are shallower as well as the grooves in the coupling. First picture left one is the 1918 Model TT rear end one. In the second picture the top is the 1918 Model TT rear end one.

[StevenS]

On a side note, here are three different Model TT Truck rear end, end castings, for the brake plate and brake attachment.

This one is the 1918 Model TT Truck rear end, end casting, one with the extra piece on the bottom for the rivet to attach the brake plate. This rear end also had a two piece spider in it.

This one is the end casting for "early to mid years" Model TT Trucks. This rear end also had a two piece spider in it. Notice no rivet piece on the bottom.

This one is the end casting for "later years" Model TT Trucks. This rear end also had a four piece spider in it. Notice no rivet piece on the bottom.

[Mark Gregush]

Some time around April 1922, the thrust bearing plate #1052 was eliminated and new design T-1004-TT33 cap was used. Could be about the same time as the filler plug was added. See page 236 Service Bulletins.
The switch from 2-4 pinion spider was about January 1924. See page 280 Service Bulletins.
The splines were change around July 1919. See page 301 Service Bulletins warning not to mix the two couplers up.

[Dropacent]

Excellent, Steven ! I have had a driveshaft that had the splines machined twice, to make it usable with the later style. They didn’t throw much away!

[tom_strickling]

Nice job Steve. I have several housings, including a complete early rear end. I will have to look them over.I wish your post had been around 10 years ago when I first got interested in TT truck stuff.

[StevenS]

Some time around April 1922, the thrust bearing plate #1052 was eliminated and new design T-1004-TT33 cap was used. Could be about the same time as the filler plug was added. See page 236 Service Bulletins.

Mark,

Mine did have the thrust bearing plate (it looks like a gasket in the first picture but it is a metal plate) and the ball bearing balls were housed in a brass casing.

[StevenS]

Here is a link to VowellArt for drawings for Model TT rear ends.

https://mtfca.com/phpBB3/app.php/gallery/album/59