There
are two types of synchro's used on the roadsters. The
Borg Warner type can be on any of the roadsters, although
Nissan information indicates they didn't start appearing
on 1600s until SPL311-26315 and on the 2000s until
SRL311-11757. Both of these VINs are during 3/69
production. A lot of cars have had their transmissions
replaced which may account for discrepancies. If you look
at the picture you can see the big teeth on each gear.
Each gear also has a small row of teeth and then the
synchro ring which is either a brass-toothed ring (BW);
or a cast steel bracelet, (SERVO) with a gap in it. If
you pull the pan on your 4 speed you can look up past the
countershaft (gearshaft closest to bottom) to see the
mainshaft which has the four gears with synchros. It's
also possible to have 1st and 2nd of one type and 3rd and
4th to be the other, so check closely before ordering
parts.
FOUR
SPEEDS: When you decide which type synchro's you
have, don't assume you have a matching countershaft,
countershaft bearings and counter (cluster) gear for that
particular synchro type. Some parts scrambling went on at
Nissan. The "servo" type countershaft has one end that is
cut into a half moon shape and has a diameter of .629
inches (16mm), the "Borg Warner" type has a pin through
one end to keep it from turning and is .669 inches in
diameter (17mm). The bearings are also different as are
internal shaft diameters. Always pull the front seal
cover inside the bellhousing to check the end of the
countershaft. If it's the BW type you'll see the pin, and
the matching pocket in the cover that it sits in. Same
thing with the half-moon servo type. You may see the
"round" end of the shaft if it's in backwards, or the
half moon end, but not a shaft end with a pin through it.
The cover should have a "half-moon" recess in it. The
servo shaft can actually be put in either way as the rear
of the case is designed to keep the shaft from turning as
well. Servo type countershafts use caged needle bearings,
the BW type uses individual needles.
FIVE
SPEEDS: All of the 5th gears are the Servo type, even
if 1st - 4th are Borg Warner. Although there are
different 5-speed cases, this is due to Nissan's adding
strengthening ribs and doesn't signify which type
synchros the box has. I've looked at quite a few of these
for any stamping numbers or something that is a dead-bang
giveway externally of what's inside and as yet have drawn
a blank. You need to pull the case off the internals to
see which type you have. Even if we found a marker on the
case; after 40 years things end up wrong. Even the
factory did this. The first batch of 1963 1500s were
"misplaced" and not assembled until the end of the 1964
production; and assembled using 1964 parts!
Some
people have told me they have been successful shining a
light through the filler or drain plug while looking
through the other opening but that seems a difficult
task. A mini-camera w/an LED light might do the trick
though!
