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T-98 Four Speed

Discussion in 'Early CJ5 and CJ6 Tech' started by farm1810, Mar 18, 2006.

  1. Mar 18, 2006
    farm1810

    farm1810 Member

    Joined:
    Feb 8, 2006
    Messages:
    84
    I am doing some calculations on gearing, tire size, etc. and am looking at advantages of the 4 speed versus my current original 3 speed. From a gearing flexibility standpoint, finding a T-98 would be pretty neat, but also I understand that they are pretty rare. I have read on websites about the adapters required to install this transmission. Would someone fill me in on the advantages, disadvantages? I have read that this transmission also came in Ford trucks and other vehicles. Anyone with experience making this conversion? Thanks. R.
     
    farm1810, Mar 18, 2006
    #1
  2. Mar 18, 2006
    panzer

    panzer Super Mod Staff Member

    Columbus, OH
    Joined:
    Dec 9, 2003
    Messages:
    1,245
    Mine came w/ a T-98. It's great for off roading. First gear ia a crawler
    gear. On the street I start out in 2nd gear. Hardly ever use 1st. I use
    it mainly off road. Try this for more info:
    http://www.film.queensu.ca/CJ3B/Tech/T98A.html
     
    panzer, Mar 18, 2006
    #2
  3. Mar 18, 2006
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    Which engine do you have? The T-98 behind the F134 came stock, and is desirable these days. Not many of them around though. I believe you need the whole setup for it to work - it's alot of stuff - read post #17 here.
    http://www.earlycj5.com/forums/showthread.php?t=26646
    The Ford truck T-98 is quite different AFAIK - different input shaft, main shaft, case.

    I recall that Novak is working on a T-18 adapter for the F134. The T-18 is essentially the updated version of the T-98. You might give them a call if you are interested.

    No real reason to go with a T-98 if you have a V6 - a T-18 or a few other 4-speed transmissions are more easily adapted.

    hth!
     
    timgr, Mar 18, 2006
    #3
  4. Mar 19, 2006
    63Willys

    63Willys New Member

    CenCal
    Joined:
    Mar 19, 2006
    Messages:
    2
    I've run my T-98 for a long time, great trans until I blewed it up last fall. Here's my $0.02 on the pros/cons etc...
    +depending on year, lowest 1st gear ratio available in an early (reasonably installed, short case, mates to spicer t/c's)
    +2-3-4 splits are spaced well (SM420 "noses over" in third)
    +if you are all jeep on the drivetrain, easy to add huge improvement in all the areas you mentioned.

    The bad news...
    -Don't break it...parts are tough to get
    -thru-floor clutch/bell crank/pivot ball linkage alignment critical. If you are gonna wheel it, this linkage can bind/break at a bad time.
    -input shaft are very variable -- 15/16" jeep, 1 1/8" jeep (m715), 1 1/16" jeep (mid cj's?), 1 1/8" Ford (who cares about anything ford)

    Beyond that, your mill of choice will be a big influence. Replicating my SBCxT98xS18 today would be tough. My clutch is beyond custom made. SBCxSM420xS18 with the steel "Rube" adapter is way easier. JEEPxT18xS18 can be done (i think) adapter free.

    In fact, I am desperate for a T-98 15/16" 10 spline input shaft. Any one have any great ideas on where to find one?
     
    63Willys, Mar 19, 2006
    #4
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