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Pros-Cons of "manual valving" an Automatic

Discussion in '40- & 55-Series Tech' started by cmilliron, Jan 25, 2003.

  1. cmilliron

    cmilliron

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    Folks, I am interested in hearing opinions on which way to go when building an automatic transmission for a Land Cruiser...

    If I understand this automatic thing (Th350 specifically), it can be built to function fully automatically (like my mother's Delta 88) or the valving can be changed to make it manually shift only...

    The FJ40 that I'm building will have to be truely "dual purpose" (highway speeds and granite speeds)...


    I intend to teach my wife to climb rocks, thus the auto tranny (she is very hard on clutches even around town)... I'm having Marlin build me a 4.7 Toybox to slow the whole show down.... ARB's and Longfields in the mix.

    Would love to better understand the pro's and con's of each method of automatic tranny setup...

    Cliff
    Lodi, CA
     
  2. PHAT MAX

    PHAT MAX

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    actually i am thinking about doing the same thing...any opinions?
     
  3. Halo3

    Halo3

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    Okay, took me some digging & some head scratching, but I finally figured out where I had just seen an article about this--in the February 2003 issue of Peterson's 4-Wheel & Off-road.

    Now, the article revolves around turning a TH700R4 into a manual shifter, but, if nothing else, it may give you some ideas of what needs to be done....i.e. a gated shifter, cooling, how to cope with transmission slippage on steep grades, and changing the shift pattern from P-R-N-4-3-2-1 to P-R-N-1-2-3-4.

    Hope that helps some... :)
     
  4. PHAT MAX

    PHAT MAX

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    yes i read that too. you dont need a gated shifter tho. and slippage on steep grades is nil if you have a 700r4 with lockup. i think it would be cool to have but i think it might get old after a while.
     
  5. Halo3

    Halo3

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    Guess I shouldn't have said, "some ideas of what needs to be done...". I should have said that these were some ideas/things to take into consideration.

    I've entertained the thought of an "auto-stick" for a little while...dating back to the days when I was busy building Project: J**p in my mind.

    In defense of the gated shifter, I think this really solved some potential problems that could be found/experienced while 4-wheeling with an auto. The article outright admits that its cable-based linkage eliminates potential problems with all the known factors which can cause a solid shift linkage to bind.

    The other side to that is from my own personal experience. In my Dakota, I've found that it is REALLY easy to bounce a knee up into a column-shifted auto, and knock it from granny gear into 2nd, Drive, or, worst yet, Neutral. On the flip side, in spending ~7 years behind the wheel of HMMWVs, I've found that the "console" mounted shifter is subject to other things in the cab. I've had a cooler, that had been ratchet-strapped to the tailgate, break free & knock the shifter into a higher gear on a steep descent. I've also caught a couple of hard bumps & accidentally knocked the shifter forward with a hand or an elbow.

    IMO, the gated shifter would give one decent insurance against the Murphy-factor that seems to follow all of us on our 4-wheeling endeavors.
     
  6. PHAT MAX

    PHAT MAX

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    ok you're right :D :D

    and another possibility would be a lokar shifter with the safety lock button doo-dad.
     
  7. Niner

    Niner

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    IMO you will hate the manual auto on the road. having to shift your auto on the HWY would be a PITA. or accidentally starting in a higher gear. A friend of mine had that in his fj40 and it was great for down hill because it wouldn't shift up even if the govenor wanted to. but going up hill I didn't notice a differance. another advantage of the manual was in the snow while trying to stay on top of it he could start in a higher gear so the stall converter wouldn't dig holes. The biggest problem I saw was heat, it could make a lot of it.
     
  8. Halo3

    Halo3

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    I don't think the highway shifting would be that bad.  Let's face it, how often do you shift on the highway to begin with?

    The way I look at it, the worst part about having an "auto-stick" would be if you used it in a daily driver that sees a fair amount of stop-and-go traffic.  But, even at that, you are eliminating the hassle of having to suck in the clutch all the time...so in comparison to our manual transmissions, it really does seem to be a good concession between a full-on automatic & a manual tranny.

    Keeping it cool would be a concern, but with the number of aftermarket coolers, aluminum tranny pans (deep w/fins), and electric fans on the market these days, I don't see how it would be too much of a hassle to fab up a solution.

    As for snow & sand, I would think that with a good torque/stall convertor setup & solid valve body work, one could actually get an "auto-stick" that could comfortable start in a higher gear...without stalling.  You would just have to work on getting the torque/stall convertor tuned to duplicate what a person would do if they were driving a manual in that situation, and that is simply a matter of forcing the vehicle to a higher than normal starting gear...which is done with the valve body work.  The next piece to this feat would be to feather the clutch while feeding a bare minimum amount of throttle.  With the torque convertor providing your clutch-like slippage & the stall convertor disengaging things if the RPMs get too low...you get almost the same effect. I think the main trick would be in getting a stall converter tuned down to the low RPMs that the F-engines can operate at.

    Who knows?  Maybe this is one of those things that looks feasible on paper, but just does not pan out in real life.  :-/
     
  9. cruiserrg

    cruiserrg

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    I just got this reply back from Petersons on the Autocrawler article mentioned above in the feb 2003 mag.  Thought I would share, I think I may do some of the same mods when I get there on my project.