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Truck 4-speed Transmissions As I Understand Them

Discussion in 'Early CJ5 and CJ6 Tech' started by timgr, Oct 27, 2020.

  1. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Sorry, to me your questions don't make any sense. If you want to connect the transmission to a 225, why don't you? That's what it was paired with originally.
     
  2. Wmi68CJ5

    Wmi68CJ5 Let the Sun Shine!

    My thought is to use the 6.32-1 Jeep case with the front parts( bearing retainer and adapter plate) from the Jeep 4-1 to be able to adapt it to the dauntless easily
     
  3. oldtime

    oldtime oldtime

    To use your bearing retainer and bell house adapter plate the main drive stick out length must match.
    How far does your main drive stick out from front of transmission ?
     
  4. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Still puzzled. A '71 4.1 T-18 already matches the 225. What are you missing?
     
  5. oldtime

    oldtime oldtime

    Tim, I’m thinking he wants to swap to a wide ratio gear set and use the Jeep factory narrow ratio bell adapter plate.
     
  6. Wmi68CJ5

    Wmi68CJ5 Let the Sun Shine!

    yes this. If the stick out length is the same then the only difference between the two is the bearing retainer and the plate to be able to make the wide ratio work with the dauntless. Ideally I wouldn't need to swap anything from the wide ratio case other than the retainer and plate from the close ratio to make it work. Just a thought.
     
  7. fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    This is probably apples and oranges and will probably raise more questions than it will answer but...
    [​IMG]
    AMC bellhousing, T19 wide ratio, 80' Scout D300
    looks to be a small adaptor between trans and t case
     
  8. oldtime

    oldtime oldtime

    Jeep used over a dozen different maindrive gears so matching the length is a must.
    Secondly the 4.02 gear sets will not mate with 6.32 gear sets.
    So you would essentially be putting your bearing retainer and adapter plate onto a wide ratio transmission.
    Also the wide ratio used a neoprene maindrive seal.
    I expect that’s what your Jeep marrow ratio T18 bearing retainer was set up for, but not sure on that.
     
  9. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Ok - first, the only wide ratio transmissions in a CJ are '77-79. '76 is 4.1;1. I believe these are all short stickout and only easily connected to an AMC motor.

    There were wide ratio Jeep T-18 transmissions in Wagoneers and J-trucks, but I don't see any reason to believe these would be compatible with the 225 transmission. Even if they were, you can't just change out the MDG - you'd need to change (effectively) all the gears, to the wide ratio type.

    You could use the main shaft and the transfer case adapter from this transmission and swap them into a Ford T-18. That would have the right stickout for the Buick bell housing. Novak has a page about mating Ford transmissions to GM bellhousings. This approach was covered earlier in the thread.

    There was a T-18 in the Wagoneer with the 350 Buick. However, it has a very long MDG and an adapter that's about 5" thick. Earlier in this thread it was offered as a bolt-in possibility for the 225. But you would use nothing from the transmission you have now.
     
  10. oldtime

    oldtime oldtime

    Fesser, that’s nice....a Texas pattern D300 ?
    Looks like it...
    4.02 gears ?
     
  11. Bigdaddy13

    Bigdaddy13 Member

    'bout to pull the trigger on a rebuilt SM420/big-hole D18 setup for my buick motor. :) Stoked. What I think I know:

    1. Bell bolt pattern is matching GM pattern on face of 420.
    2. Bell bore/bearing retainer size is the standard small GM size
    3. Stick out of 6.5" should be good with my bellhousing depth
    4. Input shaft spline count and size should be the same (1 -1/8", 10 spline input)
    5. I'll lose 2.625" of drivetrain length automatically from removing T90J spacer, which should offset the fact that the sm420/D18 setup is about 4" longer. I'm hoping the 1 3/8" reduction in rear driveshaft length has minimal impacts.
    6. Weight down low - about 60lbs more, I think? - is welcome to offset weight of family cage.
    8. Exhaust being side dump means I have zero exhaust clearance issues. :) I'm going to have a shop help me with a custom setup once these are installed.
    9. Planning on having to heat and bend the shifter to clear the dash.

    I'm fine modifying my original crossmember, and my tranny cover has already been modified for the T90J setup, so no issue there. This forum is a wealth of knowledge and I blame y'all for helping separate me from my money. :D
     
    Last edited: Jan 5, 2021
    Fireball likes this.
  12. fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Yes on Texas pattern. 6.32 gears as far as I can tell by spinning the output in first. AMC bellhousing. It keeps me looking for another intermediate to put it in.