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3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 1:07 pm
by accuratemodelmaker
Hello everyone,
After being away for several years, I have decided to renew my membership and return to this forum with what will hopefully be received as a interesting project, worthy of members help.
Years ago I started a plan drawing of the Model T transmission, mostly because I wanted to know how such a simplistic mechanical device actually worked. Over time I grew increasingly interested and started a 3D representation. However, not having all the parts has been difficult to say the least, in obtaining accurate measurements. I had some of the parts from 2015 and recorded what I could then. Much of the remainder has been educated guesswork, and some obtainable info. The ultimate goal with this project is to complete the transmission plan that I started years ago and offer it up anyone who might want such a collectible.
I'd like to request, anyone who has some free time to lend, help with parts measurements. Either contact me here or via my e-mail address
customreplicas@att.net. I would state that this is based on the earlier version (around 1915). Hopefully these previews will give some idea of what I'm trying to accomplish.
Many thanks in advance,
Jim Key
Accurate Models
5130 Farm Place Dr.
Woodstock, GA 30188
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 1:17 pm
by varmint
I would think that obtaining a transmission for the project may be worthwhile. You can always sell it afterward.
Vernon
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 1:24 pm
by speedytinc
15 transmissions didn't have starter ring gears.
The only part I can identify as actually 15 is the 3 piece triple gears.
You got a long way to go. Pre 16 transmissions are very different to the mostly post 1920 parts I see here.
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 1:39 pm
by accuratemodelmaker
I based the 1915 on there being two bushings inside the brake drum shaft. Read they changed in 1916. Really no other reason.
When did the starter and ring gear begin? I'm not opposed to dating this correctly, or altering the plan to make this correct.
As to acquiring a Model T transmission to measure off of, the idea has crossed my mind, but simply cannot afford that right now.
Thanks for the opening critique.
Jim Key
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 1:45 pm
by Dan Hatch
Jim I see your in Woodstock Ga. Email me by forum. I am in zip 35173. I think I can hook you up. Dan
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 2:06 pm
by speedytinc
accuratemodelmaker wrote: ↑Thu Jan 15, 2026 1:39 pm
I based the 1915 on there being two bushings inside the brake drum shaft. Read they changed in 1916. Really no other reason.
Lack of upper bushing(2nd) was done late, 26-7?. 15 had a big brass hat bushing that was part thrust bushing.
The casting is very different dimensionally & visually. Different clutch disk count & a thick spacer.
When did the starter and ring gear begin? I'm not opposed to dating this correctly, or altering the plan to make this correct.
19, but the hat bushing remains.
I would date what you have as 21-25. Not 100% sure off the top of my head when the riveted triple gears were discontinued.
As to acquiring a Model T transmission to measure off of, the idea has crossed my mind, but simply cannot afford that right now.
A CORRECT early transmission is not going to be that easy to acquire.
I am looking for an early brake drum to finish my study. Good ones get reused, bad ones get pitched & replaced with later ones.
Thanks for the opening critique.
I have been recently studying the differences.
There is much disinformation & incorrect information mixed with a few correct facts in past forum posts.
You have to know to recognize what was correctly posted.
Jim Key
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 3:09 pm
by accuratemodelmaker
The earlier brake drum drum is what I am after. I was told they replaced the thrust bearing with 3 washers (.026", .042", .042") to create an .015" to .027" clearance.
If 192something is what I am making, then so be it.
I based the brake drum off ebay shots labeled 1912-1920 or so. I am not making the 25-26 wider brake drum and drive plate.
Will be interesting to see what the members here come up with. I did look at Martin Vowell's drawings as well.
Thanks again,
Jim Key
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 3:51 pm
by speedytinc
"The earlier brake drum drum is what I am after. I was told they replaced the thrust bearing with 3 washers (.026", .042", .042") to create an .015" to .027" clearance."
No.
Part of the misinformation Ive been wading thru.
The hat bushing was replaced by 3 - .042 washers from early 20 on. Clutch hub changed also.(service bulletins)
If you don't have a usable hat bushing for your early rebuild, you can use 2 of the .042 washers & a special .026 washer. That combination replaces the obsolete hat bushing. This is a vendor provided fix. Not OEM as best I can tell.
OR.... you use the 3 thick washers & a later clutch hub. Or you can remove .015" from the early clutch hub thrust surface with the 3 .042" washers.
Gets messy don't it?
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 4:28 pm
by accuratemodelmaker
Yes, it does. But, I am taking notes and will endeavor to make a plan that reflects what ideal O.E.M.
I suppose then, that shooting for 1920 is perhaps the best shot, or is it 1925?
Is this the correct Clutch disk drum?
Thanks again.
Jim Key
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 4:56 pm
by speedytinc
1920 after April? (my reference material is @ home)-1925 same until the wide drum
"Is this the correct Clutch disk drum?"
This is the most confused part. How to identify.
Since I see ford script on top, I would say, yes, its correct for 20-22?.(late using the 3 thick thrust washers.)
Some time later the back side has a beefer looking casting. Probably 22-27.
As another point, on the 3 washers. The thin one I had & are available look the same OD wise as the thick washers.
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 5:30 pm
by accuratemodelmaker
Okay, getting somewhere. Will add to my notes. Our discussion today has been very enlightening.
Here is the back of my brake drum (thus far). I tried to match the photos of the drum we had.
Having trouble IDing the Drive plate bolts. Says they are 3/8" x 13/16" - 16 TPI - coarse.
Thanks again,
Jim Key
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 5:34 pm
by speedytinc
3/8-24. Fine thread. I cant confirm length where I am now.
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 8:58 pm
by John E. Guitar
Nice work.
I drew up the Model T transmission for a university project back in the nineties using Solidworks 98.
I saved it all to floppy disks which unfortunately have long since disappeared.
Re: 3D Model T transmission project - help needed
Posted: Thu Jan 15, 2026 9:44 pm
by accuratemodelmaker
Thank you. This is a project full of ever changing details, as today pointed out.
I admire anyone who has attempted to recreate this transmission.
Jim Key
Re: 3D Model T transmission project - help needed
Posted: Fri Jan 16, 2026 5:04 am
by dykker5502
Can't you get original blueprints from the Benson Ford arhives?
Re: 3D Model T transmission project - help needed
Posted: Fri Jan 16, 2026 9:21 am
by J and M Machine
dykker5502 wrote: ↑Fri Jan 16, 2026 5:04 am
Can't you get original blueprints from the Benson Ford arhives?
Yes: as we had to. Making the drums and gears to their exact dimensions and specifications.
You have to pay for them and we had to sign an agreement.
Re: 3D Model T transmission project - help needed
Posted: Fri Jan 16, 2026 12:08 pm
by accuratemodelmaker
I have the general plans from the Henry Ford archives, but did not know there were more detailed plans available from Ford. May I contact you privately to ask who you spoke with at Ford for such info? Not sure I can afford the usage fees right now, but worth checking into. In the meantime, I will just measure actual parts as they become available.
Jim Key
Accurate Models