I was paging thru Triumph Spitfire & GT6, A Collector's Guide, Graham Robson,
last night. Yes, I
received my order from VTR books immediately after I posted questioning the
delivery service!,
figures... Anyway, in appendix D, gearbox section, it states:
"Four-speed all-synchromesh type
This design was first developed for use in the Vitesse 2-litre
and GT6 models, but wider-ratio versions were later adopted
for the Spitfire and Toledo/1500TC family saloons."
This got me thinking, soooo...I jotted down the following:
(I think this is correct..if not, my most humble apologies, and please
disregard the rest of this
posting)
Overall gearing using Overall gearing using Overall gearing using
3.27:1 rear w/GT6 3.89:1 rear w/GT6 3.27:1 rear w/Spitfire
gearbox ratios gearbox ratios gearbox ratios
1st - 8.666 10.309 11.458
2nd - 5.814 6.916 7.057
3rd - 4.100 4.878 4.558
3rd/OD - 3.280 3.902 3.647
4th - 3.270 3.890 3.270
4th/OD - 2.616 3.112 2.616
I like the idea of the tall gearing for highway cruising using the 3.27 rear
w/OD (I believe it
works out to something like 25mph/1000rpm) but I also don't want to give up too
much on the low
end. My question is; Are the wide ratio gears from the Spitfire transmission
interchangable with
those in the GT6 gearbox? Is the entire gearbox interchangable? Has anybody
done this? If it can
be done, what would the reasons be for not doing it? On pg 82, G. Robson
states, "In retrospect,
I am sure most people see this as a mistake. A GT6 with a 3.27:1 axle and
overdrive was really
far too high-geared, and it is significant that a high proportion of 'special
order options' were
placed." Special order option meaning the 3.89:1 rear. It seems to me that
the wide ratios would
be better suited to an engine with a broader torque band (like the GT6's) and
the close ratio
gears would be better for a motor with a narrower torque band (like the
Spitfire's). Thanks in
advance for your collective insight and opinions.
bkh
'71 GT6
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