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t-case ?

Discussion in '40- & 55-Series Tech' started by 74bogger, Jul 31, 2003.

  1. 74bogger

    74bogger

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    i have a quick question, i dont know a hole lot on drivetrains out of cruisers and can someone please help me, what is the 3-speed t-case i know it is a transfer case and i know what it does i just dont know what (if there is ) the difference is between the 3-speed t-case and the one in my 74 fj40 any feed back would be greatly appreciated


    ???
     
  2. hammerhead

    hammerhead

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    3spd t-case comes behind 3spd trans.
    4spd t-case comes behind 4spd trans.
    3spd has slightly lower reduction.
    '74 has 4spd.
     
  3. CruisinGA

    CruisinGA

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    The 3spd case is merely the transfer case that was behind a 3 spd tranny from the factory, and the 4spd case is just the t-case that was behind a 4 spd tranny from the factory.
    Your 74, like mine has what is known as a "3 spd" t-case. Even if you happen to have the optional 4 spd, you still have a 3 spd t-case with a different input gear. (74 is a transition year).
    3 spd cases have slightly lower gearing, yet not all are more desirable. The early 3 spd cases were made out of a more brittle metal, and did not have as much reinforcement as later ones. So you (like me :D ) have what's generally agreed upon as the most desirable transfer case put behind FJ40's from the factory. ('84 split cases aside)
     
  4. hammerhead

    hammerhead

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    Wait a minute. Your telling me my '74 has a lower ratio than later models? Same as 3spd? I don't need to switch out my t-case to this 3spd I have sitting on the floor?
     
  5. CruisinGA

    CruisinGA

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    From what I've heard, the 4spd that came in 74's is the same as 2F 4 spd, and the case is a 3 spd case with a different gear to adapt to the 4 spd tranny.
    This is my understanding, please don't kill me if I'm wrong. :-\
     
  6. Gumby

    Gumby Supamod Staff Member s-Moderator

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    Without looking it up, I think the 74 had a slightly lower numerically low than the 3 speed, but better than the 75 four speed.
     
  7. woody

    woody Internet Fireman Staff Member

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    75+ 4-speed FJ40/55 t-cases have a 1.999:1 low ratio, 16 (or is it 19?)-spline input gear.

    73- 3-speed FJ40/55 t-cases have a 2.313:1 low ratio. 10-spline input gear.

    '74 is a morph year...they swapped to the 4-speed tranny but still have 3-speed cases laying around, so the early production models got a transition gear with the proper input spline to match the early t-case. LAter-74 production models have the 1.99 case.

    The ONLY way to tell is to count gear teeth or count t-case rotations for every 1 tranny revolution...requires opening up the t-case DS inspection cover.
     
  8. 74bogger

    74bogger

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    my cruiser was made in early 74 i think may but not sure (i cant look at it right now i dont have it with me) but i know that was made earlier in the year so waht your telling me is that i have the 3-speed t-case from earlier models ?
     
  9. CruisinGA

    CruisinGA

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    He's telling you that you might, the only way to know for sure is to count the gear splines or open up the transfer cover and count revolutions.
    You could do it the low-tech way and get a buddy with a stock 4 spd and a 4 spd case and drive in first gear, 4lo with the same engine RPM's (Tach required) and see who goes faster.
     
  10. 74bogger

    74bogger

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    how do i count the gear splines? do i have to remove the t-case? is there possibly a serial # i could look for? ???
     
  11. CruisinGA

    CruisinGA

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    To count gear splines you have to take the gears out of the transfer or at least take out the case and open it up. I don't know about a serial.
     
  12. 74bogger

    74bogger

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    what do i do to count the # of revolutions? thanks for all the help
     
  13. CruisinGA

    CruisinGA

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    [quote author=74bogger link=board=1;threadid=4041;start=0#msg30028 date=1059849325]
    what do i do to count the # of revolutions? thanks for all the help
    [/quote]
    I don't know exactly how you would do it.
    But heres another way.
    Do this, go put you car in lo, 1st gear and drive. Tell me your tire size, your R&P ratio, your RPM and your speed and I do some math and tell you which case you have.
     
  14. 74bogger

    74bogger

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    i cant do that right now because im outta town until the 9th and im in the process of rebuilding the body right now but when i get to the point to where i can drive it in my front yard at least(which should be very soon) i will email you all of the info is that cool?

    or maybe you could tell me how to do the math so i can do it and not bother you
     
  15. rick_d

    rick_d

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    3sp (all, to best of my knowledge) are 2.31:1
    transitional 4sps 1974/5 are 1.99:1
    regular 4sps 1974-1980 are 1.96:1
    1981-1990? 4sps are 2.2X, there is a change 34mm to 38mm idler years.
    1983+ H55's are 1.99:1 ) look for 38 tooth low range
    autos are 1.99:1 (just had to help OH a 1989 FJ62)- has 38 tooth low range.
    there are alternate cuts in these low range- they can be forward or reverse cut.
     
  16. CruisinGA

    CruisinGA

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    [quote author=74bogger link=board=1;threadid=4041;start=0#msg30046 date=1059865671]
    i cant do that right now because im outta town until the 9th and im in the process of rebuilding the body right now but when i get to the point to where i can drive it in my front yard at least(which should be very soon) i will email you all of the info is that cool?

    or maybe you could tell me how to do the math so i can do it and not bother you
    [/quote]
    Dude its cool, just email me the stuff and I'll post with the results. I'd like to know what it has as well.
     
  17. 74bogger

    74bogger

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    ok when i can get to it i will email you the info needed thanks
     
  18. 74bogger

    74bogger

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    i havent looked at my transfer case yet because im still outta town but in regards to what everyone has said in this thread about the t-cases in what models i have found something that i thought id share with all of you check this link out http://www.marks4wd.com/lc-fj40-info.htm

    im not 100% that this is correct so please dont kill me if this is wrong
     
  19. IDave

    IDave

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    Don't think it is entirely right. 4 speeds were never put into the FJ40 until 74 model year, certainly not 1969, at least not in the US.
     
  20. dinkleberry

    dinkleberry

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    I seem to remember the axle ratio went to 3.73:1 in 1980 or somewhere close to that.