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Hot Rods Jeep T-5 to model A conversion

Discussion in 'The Hokey Ass Message Board' started by Departed, Sep 1, 2017.

  1. Departed
    Joined: Dec 20, 2010
    Posts: 49

    Departed
    Member
    from Canada

    I've searched a bunch of treads about this and all I could find was a bunch of confusing information about the conversion.
    I have a stock 31 Coupe A and I would like to upgrade to a more modern transmission and it seems like the Jeep T-5 is the one I would like to go with because I want to keep the torque tube and not cut a notch in my cross member. (or very little notch..)
    I've also searched on jeep Transmissions and noticed the T90 is very similar to the Model A transmission... anyone ever tried to use one of those ??
    My questions are...
    1- what will I need to connect the transmission to the motor ( bell housing, clutch, pressure plate, adaptor, throw out bearing etc etc)
    2- How to get the torque tube to fit in length with the new transmission which is most likely not the same length of the stock one? can one cut and shorten a torque tube and shaft?
    3- Mechanical brake cross brace mods?
    4- clutch pedal (lever) mods?

    Thanks
     
    Last edited: Sep 1, 2017
  2. Maybe I am just getting old but I would go with standard adapters to use an early Ford V8 trans (preferably 1939) or a Model B trans (preferably with the later gears). When compared to a Model A they are a more modern. I think I would spend money to convert to hydraulic brakes before I upgraded the transmission, not to imply they are tied together

    Charlie Stephens
     
  3. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,093

    Mr48chev
    ALLIANCE MEMBER

    There may be a use mostly original parts to do it way but this link takes you to a kit that lets you bolt a 39 trans to a Model A block http://www.snydersantiqueauto.com/transmission-adapter-kit That means that you could bolt an adapter to that adapter to hook up the T-5.
    This is saying that the Jeep trans has the same bolt pattern as the Chevy trans http://www.novak-adapt.com/knowledge/transmissions/manual/t4-t5
    That may mean the Jeep trans behind the old "iron duke" 4 banger though. They rank down on it but a 4 banger shouldn't over power that trans.
     
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  4. manyolcars
    Joined: Mar 30, 2001
    Posts: 8,063

    manyolcars

    The 84-87 F150 fully synchronized 3speed transmission with overdrive is an excellent choice. Got one in my avatar. Did not cut my crossmember
     
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  5. fiftyv8
    Joined: Mar 11, 2007
    Posts: 4,886

    fiftyv8
    Member
    from CO & WA

    Don't limit yourself, as I find one modification generally leads to another.
    Sometimes thru necessity but mostly for practical and compatibility requirements.
    I'd be looking at what works best and easiest and would also be thinking brakes and open drive shaft.
    That is not a bad package.
    Next thing you know you will be looking at steering boxes etc...
    That F150 tranny mentioned above is one I know has been a popular choice.
     
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  6. Rex_A_Lott
    Joined: Feb 5, 2007
    Posts: 993

    Rex_A_Lott
    ALLIANCE MEMBER

    Search here for Crazydaddyo .He made adapters to do what you are looking at. Good Luck
     
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  7. Kiwi 4d
    Joined: Sep 16, 2006
    Posts: 2,557

    Kiwi 4d
    ALLIANCE MEMBER

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  8. Departed
    Joined: Dec 20, 2010
    Posts: 49

    Departed
    Member
    from Canada

    I disent know about that one... I guess you have to shorten the torque tube/shaft and radius rods a couple inches ? Noticed any change in handling with the suspension geometry changed ? (I'm guessing not..)
    Also, what parts did you need to hook it up to the motor, clutch pressure plate etc?
    What other mods did you have to do if any?


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  9. Binger
    Joined: Apr 28, 2008
    Posts: 1,618

    Binger
    Member
    from wyoming

    I used the trans adapter built by Crazydaddyo. I used a T-5 from an S-10 that he was building adapters for. On the above t-5 thread there is a picture of the adapter plate to go from a A bell housing to the S-10 T-5. With the stock A bell housing you will need a special clutch plate or an adapter shaft. If you use a AA bell housing you will need to modify the end of the input shaft as it will be too long. I had a machinist friend of mine help me make the adapter from an old A input shaft and the center section from a T-5 clutch. I had to shorten the torque tube and drive shaft 13 1/2 inches in order to make it all work. Here is a few pictures of what I did. Hope this helps.

    clutch adapter.jpg clutch adapter 2.jpg Finished chassis 1.jpg
     
  10. Binger
    Joined: Apr 28, 2008
    Posts: 1,618

    Binger
    Member
    from wyoming

    Forgot to mention that I used later radius rods and had to cut them down.
    [​IMG][​IMG][​IMG]


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  11. Departed
    Joined: Dec 20, 2010
    Posts: 49

    Departed
    Member
    from Canada

    Nice project! But I rather not cut my cross member. I would if the car wasn't in such a good shape.. Everything is there and the car looks like it was stored back in the 40s and just pulled out of a barn. I'd hate to hack some stuff off like that...


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  12. enjenjo
    Joined: Mar 2, 2001
    Posts: 2,485

    enjenjo
    Member
    from swanton oh

    It can be done with a Jeep trans, but not simply. The same thing can be done with an S10 trans, 2 or 4 wheel drive. You can make or buy a plate adapter to mate a Jeep T5 to a truck, AA, bell housing. The Jeep T5 had the Ford type bolt pattern. The guts can be installed in a GM bolt pattern case. Jeep and GM both use the same length input shaft. Lighten the flywheel to 18 to 20 Lbs, and redrill for a 40 Ford pressure plate. Use a Jeep clutch plate to match the diameter. Make a sleeve that can be pressed on the Jeep front bearing retainer that matches the ID on the Model A throw out bearing.

    To avoid notching the crossmember, first you cut the Jeep transfer case adapter down to the back of the countershaft bulge, or the shift rod boss, whichever comes first, and weld a 1" aluminum plate to the back of the shortened adapter. Machine a hole in the center to fit a sealed ball bearing that is a light press fit on the OD of a model A Ujoint yoke. I use the back wall from a junk case to hold it in the lathe. Locate the ball bearing with a shoulder on the inside, and a snap ring on the outside. Drill the 1" plate for the torque tube ball retainer, and shorten the torque tube and drive shaft as needed. It should come out just ahead of the crossmember.

    You have to shorten the main shaft to match and respline it to take a Model A Ujoint yoke. Moser Engineering can do it. The Jeep main shaft has a 23 spline output, and nothing other than a transfer case matches it. A 23 spline Toyota yoke is close but the shaft still has to be machined to fit. The OD of the shaft has to be cut down, and the splines cut deeper. Moser can do that too.

    A Jeep T5 has a 4.03 first gear and a .86 overdrive which works well with a Model A.
     
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  13. Binger
    Joined: Apr 28, 2008
    Posts: 1,618

    Binger
    Member
    from wyoming

    I understand about not wanting to cut on the cross member. There is a picture later in the T-5 adapter thread that shows a chassis that has only a few notches cut into the My project was a bit different because I built that frame. I needed to use the later radius rods on the rear in order to clear the 6" Z I built into the frame. No matter which way you decide to go I think you will be happy with the way a Model A drives with the T-5. I love mine and have put probably 2000 miles on since I finished the car last fall.

    Here is another thread about a conversion

    https://www.jalopyjournal.com/forum/threads/jeep-t5-trans-in-the-torquetube.256226/

    and here are a couple of pics of a slightly modified frame with a t-5. I think this one is using the AA bell housing.

    t-5 stock frame.jpg t-5 stock frame 2.jpg t-5 stock frame 3.jpg t-5 stock frame 4.jpg
     
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  14. Departed
    Joined: Dec 20, 2010
    Posts: 49

    Departed
    Member
    from Canada

    I found a T-90 from a jeep. Anyone here know if that would be better fit ?


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  15. manyolcars
    Joined: Mar 30, 2001
    Posts: 8,063

    manyolcars

    I cant cut and paste. google manyolcars HAMB synchronized 3 speed w/overdrive
    Aug 25 2012 Theres lots of pictures
     
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  16. enjenjo
    Joined: Mar 2, 2001
    Posts: 2,485

    enjenjo
    Member
    from swanton oh

    Years ago there was a guy up by Tawas city Mi that had a Model A pickup with the stock engine, a T90 trans, and the Jeep transfer case and Front axle The only stock drivetrain 4x4 Model A I have ever seen. Up to 56 AMC used a T90 with a closed driveshaft, might be something to look into. I don't know how much interchange there is between the side shift T90 and the top shift T90, but I suspect the internal parts are the same.
     
    Last edited: Sep 11, 2017
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  17. Departed
    Joined: Dec 20, 2010
    Posts: 49

    Departed
    Member
    from Canada

    Thanks! This is the exact info what I was looking for.


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  18. Junkcarguy
    Joined: Sep 22, 2014
    Posts: 10

    Junkcarguy

    If your still working on it t90 stuff is plentiful side shift and top shift interchange I have a top shift in a side shift case with the side shift holes plugged all early on ford built their Jeep prototype with a 9n tractor engine and a model a trans from the factory If memory serves me the flat top Jeep trans and the t90 both interchange Willys 2wd wagons trucks and surrys All had a 2wd option with the t90 later jeepsters had a three speed with overdrive but were column shift I have piles and piles of parts went from the Jeep bug to the hot rod bug lots of interchange
     
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  19. Departed
    Joined: Dec 20, 2010
    Posts: 49

    Departed
    Member
    from Canada

    Thanks for the info. However, I went with a T170 (it's a 4 speed OD) which will be very good for the low ratio rear end on the model A.
     
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