Bob,
> There is the problem with the starter location and tranny input
> shaft. Is it possible to swap the engine backplates and tranny
> bellhousings to overcome the starter problem? Can the fly-wheels
> be changed to accomodate the input shaft?
I presume you are talking about using the flywheel, clutch, backplate and
bellhousing from the Spitfire. While I've never measured them it appears at
first glance to be possible to bolt them up, however you would soon find
that you wouldn't be able to bolt the starter on because of the oil
filter/block casting interference (probably the reason for the starter
placement in the first place). Even if you could use the above mentioned
parts the clutch would be much too small, it may be possible to
re-drill/reface the flywheel for a larger clutch but really never looked
into it for the above mentioned reasons. However the real problem with the
Spitfire tranny is that the materials used in the manufacture of the
layshaft and some of the gears of the GT6 are of much stronger material to
handle the additional torque. Also the ratios in the GT6 box are much more
suited (closer ratios even though were ignoring them) for the six than the
Spitfire box. I don't believe that the single rail box is necessarily
'stronger', but it was definitely an improvement. The main areas addressed
in the single rail verses the three rail box were in the input to output
shaft needle bearing. It was made larger than the old unit to prevent
premature wear in this area. Also to eliminate the rail system to improve
'shifter feel' over the old three rail unit and to reduce parts inventory
(it was common to the Austin Marina).
And again one can't simply use the input shaft (1'st motion shaft for some
of you) because of the difference in ratios (layshafts, gears etc.). You
might be able to use a layshaft, first motion shaft (by regrinding to match
the new needle bearing size) and selected gears from the GT6 into the marina
box, but even if you could you would still be faced with modifying the GT6
bellhousing for clearance for the shifter rail which extends into the
bellhousing on the single rail unit, which may or may not interfere with the
clutch actuation. Did I mention clutch actuation is different than that of
the Spitfire? Anyway, you can see that it's not all that simple. The GT6
unit is strong enough for normal use, just don't expect to drag race and
power shift if you want it to hold together! And if you going to do that it
would probably be eiaser/better to use a TR6 box.
Barry Schwartz
Bschwartz@encad.com (work)
Bschwart@pacbell.net (home)
(San Diego)
70' Spitfire (major surgery almost done) , 72'-V6 Spitfire (daily driver)
70'GT6+
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