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  1. #1
    Member
    Join Date
    Jan 2009
    Posts
    34
    Location
    East of Dallas TX
    Tractor
    Komatsu D31S-16

    Default Komatsu D31S basic tranny questions

    I've had it for 2 months and only get to mess with it a few hours a week right now so its taking me awhile to learn all the the stuff on it. Its a 78 model with power shift tranny. I keep saying I'll get the manuals next week. Anyway, on my Ford tractor the hydrolic fluid and tranny fluid are the same with the same resivour. I discovered yesterday that on the D31S its different (I think). Below are pics of 2 dip stick tubes in front of the seat. They are very close together and one stick is flat and the other stick is round. I'm wondering if one is tranny fluid and the other final drive fluid. The hydrolic fluid is under the right arm rest. Does anyone have an idea what they are and what fluids s/b used?

    In the close up pic you can see the shifting/valve body plungers at the bottom of the fluid tubes. The plunger on the left (right side of D31) is all the way in for reverse and out for forward (or maybe vis versa). The one on the right is the gear plunger and selects 1st, 2nd, or 3rd gear. The gear plunger moves in and out about the same amount as the f/r plunger but I only have 2 speeds instead of 3. I'm not sure which speed I'm missing but if I had to guess it would be 2nd. Any ideas on how to proceed with investigating the missing gear issue. If I remove the lever that controls the gear plunger will it pop out?

    trannyvalvebody1.jpg picture by dcara - Photobucket

    trannyvalvebody2.jpg picture by dcara - Photobucket


    Also, below is a pic of a loose bolt on the left side of the pic (right side of D31) below the valve body. I can't see that it holds anything but to tighten it I had to remove the lock washer. I might try a slightly longer bolt but I'm curious if it will cause an interference problem inside the tranny.

    trannybolt.jpg picture by dcara - Photobucket

  2. #2
    New Member
    Join Date
    Apr 2009
    Posts
    4

    Default Re: Komatsu D31S basic tranny questions

    THE FRONT TUBE IN THE PICTURE IS THE TRANSMISSION AND THE BACK TUBE IS THE BEVEL GEAR/ PINION CASE, SCRATCH A "T" AND AN "F" ON THE RESPECTIVE PLASTIC TOPS AND YOU'LL KNOW QUICK FROM THE SEAT NEXT TIME. THE CHROME ROD COMING OUT OF THE TRANSMISSION AS YOU DESCRIBE SHOULD HAVE 3 DISTINCTIVE DETENTS, IF IT DOES AND YOU ARE "MISSING A GEAR IT'S PROBABLY THE CLUTCHES FOR THAT GEAR .THERE ARE 3 FORWARD AND 3 REVERSE CLUTCH PACKS. DROP YOUR BELLY PAN AND CHECK THE FILTER, "YOULL HAVE TO DRAIN THE TRANSMISSION FOR THAT" AND IF YOU FIND FLAKES ON THE FILTER SCREEN YOU HAVE CLUTCH FACINGS (CONDENSATION LOVES TO SCREW THOSE UP, IT DISINTERGRATES THEM) AS FOR THE BOLT I COULD VERY WELL BE THE WRONG ONE,. I THINK THERE ARE TWO OF THESE BOLTS THE PART# IS 01010-31465 THEY HOLD THE ACTUAL TRANSMISSION OUTER SHELL (CASE) TO THE INSIDE WORKS, THE CORRECT LENGTH SHOULD BE TIGHT TO THE CASE BUT CHECK FIRST TO SEE IF YOU HAVE THE RIGHT LENGTH. TRANSMISSION CAP. IS 13 LITERS(3.43 GALS)BEVEL CASE 20 LITERS(5.27 GALS.

  3. #3
    New Member
    Join Date
    Apr 2009
    Posts
    4

    Default Re: Komatsu D31S basic tranny questions

    FORGOT ! transmission oil is straight #30 engine oil for normal temps and the same goes for the bevel case, good quality diesel engine oil

  4. #4
    Member
    Join Date
    Jan 2009
    Posts
    34
    Location
    East of Dallas TX
    Tractor
    Komatsu D31S-16

    Default Re: Komatsu D31S basic tranny questions

    Great info. Thanks a ton, well actually about 7 tons.

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