Someone asked a couple of days ago about what causes the trans to slip out
of third gear when not loaded. While there can be a dozen causes of this,
90% of them are due to one of two things.
First, the shoulder is broken off of the top hat bushing. You can determine
if this has happened by putting the trans in third gear, removing the top
cover, grasping the output yoke in one hand and the input shaft in the
other hand, and wiggling them back and forth against each other while
looking into the top of the trans at the third gear. If this gear moves
more than a couple of thousandths axially, the bushing is probably broken
and there is no fix other than replacing the bushing.
Second, the spring-and-ball detent on the 3-4 shaft adds to this problem if
the notch in the shaft is worn or the spring has lost some tension. I
assemble all transmissions with a Spitfire reverse detent and a spring with
an extra small spring inside the stock spring. That puts enough extra
pressure on the detent that it helps a lot.
Interesting to note that comparing the TR3/4 and TR6 handbooks on number of
pounds force to disengage the 3/4 fork is about double on the TR6, around
30 lb I seem to remember, so this is not a new problem.
uncle jack
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