I am rebuilding my '67 GT6 gearbox . I laid out the parts in
sequential order upon disassembly. Between the 1st gear and the rear
transmission bearing (called the centre ballrace in the shop manual)
is a thrust washer. In my transmission there was ...an additional
0.080 thick spacer. Rearward of the bearing there was a snap ring.
What the workshop manual shows and calls for is the following order:
1st gear, thrust washer, bearing, spacer (called the centre
ballrace-circlip washer with selective thicknesses ranging from 0.091
to 0.102), I have marked up the exploded view of the rotating parts in
the trans as dismantled and scanned the page but I do not have a web
site to post to - I am more than willing to e-mail the info to anyone
that would like to take a crack at helping me solve this.
Following the shop manual, measuring for the centre ballrace-circlip
washer thickness I determined that it needed to be 0.112 thick! to
achieve the 0.000 to 0.002 axial clearance. I machined and lapped in
a spacer of this thickness.
I reassembled the box in the same configuration as was disassembled
with the washer between the thrust washer and the rear bearing. When
the box was assembled, it was virtually impossible to shift the trans
and there was no functional neutral since the there was no free play
between the synchros and the mating tapers.
So I disassembled the box, placed the washer behind the bearing as per
the shop manual. Now there is EXCESSIVE clearance between the input
shaft and the main shaft where they join at the 3/4 synchro hub. When
the trans is shifted into either 3rd or 4th and the gap is measured
between the opposite syncho and gear the gap is 0.163 (no joke!). As
a sanity check, the same gap as measured between the 1/2 synchro & hub
is only 0.094. If this is not quite clear, I have digital pics for
anyone to review but again no web site to post to. It appears that
there must be mixed parts (different vintages) in this box. It
appears that I need some thickness of spacer between the thrust washer
and the bearing with an additional shim between the bearing and the
circlip to provide the specified 0.000 to 0.002 end float. Big
question is how thick a spacer between the thrust washer and the
bearing. I have run this trans for over the last decade so I know
that the parts have meshed and mated with each other. About 6 years
ago I had the trans rebuilt using a full TRF rebuild kit. Afterwards
the trans was harder to shift into 2nd gear unless the clutch petal
was fully depressed and the shift was slower than in the other gears.
I attributed this, at the time, to a crappy Borg & Beck pressure plate
(PP was changed when the trans was rebuilt). Now I'm thinking that
maybe the 0.080 spacer is not the right thickness (bit too thick
between the thrust washer and bearing and an additional washer needed
rearward of the bearing to take up the remaining play) and
consequently there is a bit of extra drag on the synchos (due to
inadequate end float) making it a bit more difficult to shift into
If you are only familiar with the TR6 gearbox, chime in anyway since the
component layout between the first gear and the snap ring (circlip)
including the sizing of the washer appears to be the same.
I'm off in digest land awaiting your responses. THanks in advance.