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3 speed gears in 4 speed case

Discussion in '40- & 55-Series Tech' started by Slowerthanu, Feb 5, 2003.

  1. Slowerthanu

    Slowerthanu SILVER Star

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    What do I need to make it work???

    I am wanting to do this since I have a 77 and want to eventually put an SM420 or SM465 in my Cruiser, Want the 2.31 low range with stock 4speed for the time being.


    What happened to Pirate4x4.com???

    Thank in advance Dan Tubbs
     
  2. 2car

    2car

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    Specter Off ROad et al make a 'transition gear' - same as the 3 speed input gear, but with a 4 speed internal spline.  I think they designed it as an adapter for the 3 speed case to the 4 speed box, but it works anyway.  Also I believe there is extra shimming required to get the end floats correct on the idler and output shafts.
     
  3. woody

    woody Internet Fireman Staff Member

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    Actually, 2car, he's putting the entire 3-speed gearset into a stronger 4-speed case. On my list with the gears from my 69...

    Buddy of mine did it....the only thing to deal with is the shims for the idler cluster. He said he went to Toyota and they had a "variety pack" of shims he used to pick/choose from until he got the tolerances correct. IMO, it's a piece of cake.
     
  4. cruzila

    cruzila

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    Wrong, It is a Toyota gear, Non-us. They put the newer t-case behind 3 speeds. Marlin Crawler has them Doeney has then Spectre has them. THe word I got was to use the biggest shims, one on each side. That will do it or get you close.

    Scott
     
  5. Slowerthanu

    Slowerthanu SILVER Star

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    So, let me sort this out.

    I have 1. my 4 speed case 2. my 3 speed case 3. my 4 speed transmission with a 16 spline output and 4. a transition gear from any of the major vendors.

    To put my 3 speed gears in my 4 speed case and mount it to my transmission, I need to use all of the 3 speed parts, some shims and the 16 spline transition gear?

    Is this correct or am I missing something here?
     
  6. woody

    woody Internet Fireman Staff Member

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    you CAN just put the transition gear in your 3-speed case and be done with it....p-brake drums and front output nose cones interchange....but the early cases are weaker than the 4-speed later cases. (aluminum brittleness changes)
     
  7. Slowerthanu

    Slowerthanu SILVER Star

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    So the 3 speed and 4 speed cases have the same transmission bolt patterns?

    If so that makes it easier, I will buy a T-case saver and put it behind my transmission, then when I get around to the 420 or 465 it will not be so complicated to complete the changeover.

    If I call Marlin or SOR and ask for a transition gear will they know what I am Talking about?

    Woody and all, FYI you guys are awesome, thanks for helping a man out. :D
     
  8. woody

    woody Internet Fireman Staff Member

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    bolt patterns are identical...you will need to use the 5 bolts for the 4-speed case tho since the thread pitch on the 3-speeds is different.  And don't lose those spare bolts either....might need later, and not a common size.

    Marlin should, what you want is the 74 transition gear....mates the 16-spline input to the early t-case inner gears.  

    IIRC, TPI and others sell a conversion kit with the gear, bearing, spacer, and gaskets for ~$200.

    Might also post in the wanted section...I've sold 2 of these transition gears in the past.

    (EDIT: corrected the spline count for the tranny output gear...oops)
     
  9. rick_d

    rick_d

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  10. 2car

    2car

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    Yeah, I was just sayin that they sell the gear with the intention of using the three speed case (that's whar SOR told me), but it also works for the 3sp gears into the 4 speed case.

    Does anyone have a part number for the transition gear?
     
  11. 2car

    2car

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    My Bad! Please replace 'make' with 'sell'. :D
     
  12. Chef

    Chef

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    Slower, you have it right when you said"So, let me sort this out.

    I have 1. my 4 speed case 2. my 3 speed case 3. my 4 speed transmission with a 16 spline output and 4. a transition gear from any of the major vendors.

    To put my 3 speed gears in my 4 speed case and mount it to my transmission, I need to use all of the 3 speed parts, some shims and the 16 spline transition gear?

    Is this correct or am I missing something here? "
    Woody, he's going to need a 16 spline trnasition gear, not 19,-I'm sure that's a typo on your part. Also, Rick D is awesome to do biz with, he's been super helpful to me and I have no qualms recommending him over the "name brand" guys selling transition gears...Alan
     
  13. woody

    woody Internet Fireman Staff Member

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    good catch Chef...my bad....fingers have not been speeling well this week at all....lol