You ask me about updating your 4 speed TR7 gearbox...
Unfortunately I'm not a "wedge-head" so my data may be a little short on
particulars, and the last thing you mentioned ie. " Don't tell me to get
another trans" , or something to that effect, is however, my best thought.
The update that you speak of is indeed for the reverse gear, and uses a gear
with fewer teeth, hence it is a lot stronger as each tooth is stronger. The
cost of the pieces needed will amount to approx. $250. As long as you have
the trans apart (and you will need to strip it down all the way to replace
the reverse gear and the corresponding gear on the layshaft), you might as
well replace the synchros, and the bearings are a must at this point. So,
although the pieces for the update are not outrageous, the total bill will
probably come in around $600 and your labor to do this job "right".
Now here I get a little hazy, but I believe that the early TR7 4 speed is
basically a spitfire box, and even Triumph wasn't sure that it would hold up
for very long when they introduced it as they homologated the TR6
transmission as an option (never put into a car from the factory to my
knowlege, but okay'ed it for racing). The later 5 speed box is a lot better
transmission, and will basically live forever behind a stock TR7 motor. I
believe that the 5 speed is derived, or at least similar to, the Jag XJ6 and
Rover 3500 trannsmissions. I think that due to the availability of TR7's in
wrecking yards, (even in your neck-o-the-woods), the 5 speed is worth looking
into as opposed to putting money into the 4 speed. Other SOL'ers have
probably done this, but I believe that in order to fit the 5 speed you will
need to use the bellhousing, clutch, shifter, and drive shaft to convert your
car to the 5 speed setup.
Hope this hasn't put a damper on your new toy, but I think this is the best
way to "spend your money"
Nick in Nor