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First gear on output shaft, how much play?

Discussion in '40- & 55-Series Tech' started by rgentry, Mar 19, 2003.

  1. rgentry

    rgentry

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    I am about to start rebuilding a 3-speed tranny that
    is new to me. The tranny seems fine but there is
    a slight bit of play of the first gear on the output
    shaft. The shop manual has no guidance as to
    how much is too much. If I could measure this play
    it would be in tenths of a degree -- not much but
    not ZERO play either. Should I quit worrying about
    it and just re-build?
     
  2. IDave

    IDave

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    Just did this job last weekend.  You are right, there are no specs for this in any chassis manual that I could see (looked at 3 different editions).  So, I just slid the gear on and put the bearing on where it belongs:  there's really no way/shim to adjust, anyway.  All is installed and it seems to shift fine.
     
  3. Pin_Head

    Pin_Head

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    The big, straight-cut non-synchro gears almost never have any problems with wear either on the gear or on their shafts. The only problems you see are their leading edges getting chipped from shifting while the gear is spinning.
     
  4. rgentry

    rgentry

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    Yo Pinhead, thanks. The first/reverse gear in this
    case does not looked chipped, just kind of worn where the
    gear gets ground into first. I know that the gear can't
    be perfect on the shaft, it has to slide back and
    forth to shift -- so where should I look for wear? I will
    purchase the standard rebuild kit and so all of the bearings
    will get replaced. Should I also replace the synchros,
    and the shift keys? Thanks.
     
  5. rgentry

    rgentry

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    I hate to answer my own question but the Toyota
    chassis manual seems to indicate that there should
    be a maximum of 0.004" backlash in the spiral cut
    gears (2nd, direct drive/3rd) and 0.008" in the
    straight cut gears (first, reverse). I suppose that
    this can only be measured once the transmission
    is assembled and cannot really be adjusted for.

    Still not real sure how to measure backlash, though
    I'm afraid there's going to be a lot of it going
    around . . .
     
  6. IDave

    IDave

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    You have to measure backlash with a feeler gauge with the gears installed. If there is too much space, the gear is worn and you have to replace it ($$$). Thrust clearance can be adjusted for with the variously sized snap rings, in some cases.

    If you have trouble shifting (especially downshifting) between 3rd and 2nd, your syncros are almost certainly worn. They are relatively cheap to replace.