Dual transmissions - Doodlebug

[Onlybackroads]

Hello, I am thinking of putting two transmissions into my doodlebug, currently it has a regular 3-speed with a 2 speed hi-lo underdrive. Would replacing the underdrive with another 3-speed make it any slower? I'd like to get this thing to crawl. I'm sure the information is on this site but I can't seem to find it. And I haven't looked into yet, but would two transmissions bolt right up to eachother? Thanks.

[Fred K-OR]

I put an A transmission behind my model T back a few years. I found that with both transmission in reverse, it was slow----. I would think you need to do some work to get them to bolt in.

[Keith True]

Another 3 speed will help it,but a 4 speed truck transmission behind your 3 will make it crawl.They don't bolt up together,but you hang the second trans behind the first by an extra crossmember built to hold the ears of the transmission.Then you marry the input shaft to the output shaft of the first transmission,usually by making up an adapter out of the old U-joints.Thousands of farmers did this in the dooryard,it just takes a little imagination,a torch,and a welder.

[Bob C]

The easiest thing to do would be to replace the three speed with a four speed. All bolt in, no
machining. The three speed is 3.12:1 in first the four speed is 6.40:1.

Bob

[George Miller]

Originally Posted by Onlybackroads

Hello, I am thinking of putting two transmissions into my doodlebug, currently it has a regular 3-speed with a 2 speed hi-lo underdrive. Would replacing the underdrive with another 3-speed make it any slower? I'd like to get this thing to crawl. I'm sure the information is on this site but I can't seem to find it. And I haven't looked into yet, but would two transmissions bolt right up to eachother? Thanks.

I have done it with two 4 speeds. Use it for plowing snow, running a bush hog. Yes it would really crawl.

[George Miller]

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If you put both transmission in reverse you will go forward real slow. I think with two three speeds you would go as slow as you want, if you put both in low.

[Tom Wesenberg]

Two 3 speeds in first would be about 9 to 1 geared down.

Two 4 speeds in first would be about 40 to 1 geared down.

[Onlybackroads]

Wow, two 4-speeds sounds real slow! Well the reason why I want to try out two 3-speeds is because I have a couple extra on hand and so I might as well use what I have.

So does anyone know how two 3-speeds would bolt up to eachother? Any machining or adapters needed? Once again, I haven't looked at them closely enough yet so I figured I'd ask on here while I'm here.

[Tom Wesenberg]

You should have a bearing support for the input shaft of the second tranny, which would not be supported by the crankshaft bushing, as the first tranny is. The tranny input and output shafts are seperate and joined in the middle by a small roller bearing, so the front of the output shaft is inside the rear of the input shaft. Then each shaft has only one ball bearing, so neither shaft is very rigidly supported unless the input shaft has a support on the front end of it's shaft. My early John Deere 110 has the same weak design for the tranny input shaft, one bearing only on the split input shaft, and a small bearing in the middle where one shaft tucks into the other. If you study it, you will see it's a very weak design and that's why I had to replace those parts in my JD.

[George Miller]

Here is a picture of the bug when I was building it. If you look close you can see both shift levers.

[K9]

George:
What are those brakes on your bug? They are HUGE!

(I have a '53 Ford Jubilee, JD "M" (restored), and a modern JD 4310)

-Dave P.

[Ray in La Mesa]

There is an article in the latest Secrets Of Speed magazine about a fellow in Norway combining two A transmissions, one normal on bellhousing and the other backwards using the ujoint clamshell back halfs to bolt them together. He made a splined connector for the two output shafts and a custom tail shaft bearing holder for front of the second trans. He is aiming for higher crusing speed not pulling power. Anyone care to try and figure out the ratio combinations?

[Tom Wesenberg]

Originally Posted by Ray in La Mesa

There is an article in the latest Secrets Of Speed magazine about a fellow in Norway combining two A transmissions, one normal on bellhousing and the other backwards using the ujoint clamshell back halfs to bolt them together. He made a splined connector for the two output shafts and a custom tail shaft bearing holder for front of the second trans. He is aiming for higher crusing speed not pulling power. Anyone care to try and figure out the ratio combinations?

It doesn't seem like he will have good ratios, and it will also be noisey if each tranny isn't in high gear.

[George Miller]

Originally Posted by K9

George:
What are those brakes on your bug? They are HUGE!

(I have a '53 Ford Jubilee, JD "M" (restored), and a modern JD 4310)

-Dave P.

Dave that is a rear axle out of a 1928 AA The brakes worked very well. I put a pedal for each brake, so you could turn very sharp.

[Onlybackroads]

That's a neat idea George, I might have to try splitting up my brakes.

[Big Iron]

Onlybackroads Do you have the high speed worm or the low speed rear end. I have an extra low speed. if you have a high speed we could trade.

[QGolden]

Mine had two 3 speeds and a two speed rear end. And I split the brakes. I never did calculate the ratio, but if I put em both in reverse and the rear end in low, I could open her up full throttle, get out and walk around it before the wheels made two revolutions. I used to pull stumps with it, chain her up to the stump, put it in gear and get out and pry on the stump, when it came out I could walk up and climb back on. With a set of chains on the back that thing would climb a Tree.

[Onlybackroads]

Any pictures or tips for the split brake setup? Also, anyone have any pictures of two 3-speeds hooked up together?

[Barry B./ Ma.]

Mine has a Model A 3 speed hooked to an old Chevy 3 speed which is connected to a Model T worm drive rear end. Wasn't done by me, bought it that way years ago. The old farmer did a pretty good job and I've since added a Model T wood bed. Does the job well, only has front wheel brakes though.

[BrianBurkert]

I have a 1930 Plymouth Doodlebug. My great-grandfather bought the car new in 1931, and my grandfather converted it to a tractor around 1941. It has the Plymouth 3 speed with a Chevy truck 4 speed then a TT worm drive rear end. Plenty of reduction, but the real plus is the heavy cement weight cast on the back. Here it is doing some light work:
https://www.youtube.com/watch?v=CxuYFuq-kwQ