First gear on output shaft, how much play?

rgentry

rgentry

Joined
Jan 19, 2003
Messages
688
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?
 
IDave

IDave

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Jan 3, 2003
Messages
7,184
Location
McCall, ID
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.
 
Pin_Head

Pin_Head

Joined
Feb 6, 2002
Messages
15,335
Location
OC, CA
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.
 
rgentry

rgentry

Joined
Jan 19, 2003
Messages
688
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.
 
rgentry

rgentry

Joined
Jan 19, 2003
Messages
688
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 . . .
 
IDave

IDave

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Jan 3, 2003
Messages
7,184
Location
McCall, ID
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.
 

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