> The GT6 differential is *virtually* part for part identical to a Spitfire
> diff of the same year. So, the GT6 diff is no stronger or weaker in that
> respect, then that of the Spitfires, again of the same year
Barry et al, (I know that you didn't start this Barry, however am uncertain
who was!)
I agree, the GT6 diff is basically the same as the LARGER internalled
spitfire diffs. Getting a 4.11:1 'big' diff is almost impossible over here
however! (most are 3.69:1)
I must say however, that I don't understand why you would want to use a
4.11:1 diff, acceleration will be rapid, but you'll be turning an additional
1000rpm at 100km/h! Are you intending to win every stop light grand prix
(rapid gearchanging will be required) These cars aren't all that slow off
the mark anyway. At present I run a 3.27:1 and a 2500 sedan overdrive
gearbox (admittedly this gives me a much lower 1st than an original GT6
box), and really aren't looking forward to the gearing change (down, see
below) as I will go from 2500 to closer to 3000 rpm again at 100km/h!
The vast majority of 4.11:1 diffs we see are from early cars, and so also
have different size flanges (for tailshaft and axles). However we have
encountered the occasional 'oddity' such as 'big' diffs with little flanges,
and the occasional 'little' diff with big flanges!.
The test is easy, pull an output shaft, if it's about 1/2 inch in diameter
don't use it, if it's about 3/4 inch in diameter that's about as good as it
will get!
A note on the 'little' diff, my 1147/1295 (ie early motor taken out to later
capacity) spifire can (and regularly does) twist/snap off the splines from
these output shafts. I got so used to this that I could 'hear' when the
cracks had started and so would whip the inner halfshaft out before I had to
pul the diff (you can actually do that by only undering 8 bolts, the four on
the flange and the four holding the halfshaft into the diff! ... that
procedure is not described in the manual!) This car has nowhere near the
torque of even a standard GT6.
As a result of that this car will (if I ever finish the restoration) have a
Datsun diff (won't break that sucker! Subaru still use this diff in the back
of their 4wd's). The GT6 is currenty getting a subaru 3.7:1 diff and CV
jointed driveshfts! (A little machining required there!)
I would strongly recommend this for those who want to feed serious power out
of the GT6 rotoflex rear end. No more disintegrating rotoflexes. 2 inner
subaru CV's on a custom shaft on each side, and the current outer part of
the rotoflex axle machined to take the CV. Diff bolts into a 3 piece cradle,
straight into car, new tailshaft required.
Bill
Spitfire MkII
GT6+
2500 PI
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