5th gear neutral is pretty common. On earlier transmission the big nut at
the back can loosen up and that can cause big problems. On later 5 speeds
there are 2 big nuts at the back that are tightened against each other at
about 220ft/lbs. I can't imagine this arrangement loosening up but you can
still have the problem as the main shaft 5th gear itself is poorly designed.
The gear is 2 pieces (they all are) but unlike the others, 5th is just press
fit together. The other gears are splined. What happens is that the torque
being put into the outer portion of the gear is too much for the press fit
and the outer portion of the gear doesn't transmit any power to the inner
portion of the gear and thus no power to the main shaft. On the latter
transmission - I don't know what serial number they changed the rear nut(s)
to the lock nut arrangement - it won't hurt the transmission. I drove mine
that way for years. On the early ones it will cause a problem if the nut is
loosening as that lets all the gears develop very excessive end play. You
should be able to hear more gear noise/whine it that nut is loosening. They
make a new gear that is either splined or welded so that it can't slip.
Replacing the old gear with the new will fix the problem.
Brian
-----Original Message-----
From: owner-datsun-roadsters@autox.team.net
[mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of James M Koken
Sent: Tuesday, April 03, 2001 12:04 AM
To: datsun-roadsters@autox.team.net
Subject: 5 speed tranny
A friend has a 2000 and the 5th gear does not "exist"/ All other
gears are ok.
What is the problem and what is required to fix it? If the big nut falls off
of the main shaft, is this the only symptom?
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