This is the first time I've ever heard of anybody breaking the big internal
shafts, I would like to guess they were the early ones with the cut splines,
the later rolled splines (changed around 1968?) are possibly indestructable.
There are three different sets of 4.55 gears that will fit a Spitfire -
Standard 10 and herald 948 TC units use a strange carrier with smaller
crownwheel bolts and the small internal shafts. There is a normal Herald set
(13/60 - Hong Kong and Madeira markets) that can be run with big internal
shafts but still uses the smaller pinion tail bearing. The best set is the
early Marina Van one which goes straight into the late Spitfire/GT6 unit, I
aquired around 200 of these (I would think there are still some left at
Canley Classics) which came out of complete rear axle assemblies which
Caterham Cars had bought from Rover (they changed them for 3.63s) to fit the
Seven. When they are gone that will be it, as I doubt they will be remade.
----- Original Message -----
From: "Rocky Entriken" <firstname.lastname@example.org>
> Oh, and since I've been running the bigger diff with the bigger GT6 inner
> axles, I've only broken a couple of those over several years' time.
> Kipping mentioned shearing off diff teeth. I've done it at least twice,
> times on 4:55 gears, which I attribute to two things -- one, thinner
> and two, bad driving technique. Both times I did it, It was a rather
> downshift situation where I threw extreme reverse load on the drive train.
> In fact, it was on the same corner of the same autocross course a few
> apart. Downshifted too late, actually. And both of those were stock
> units. I went back to my old friend Ted Schumacher for another, and he
> out. About six months later he called me and asked if I was still looking
> for 4:55 gears and he had some new ones. Not quite sure what they were,
> they looked beefier than the original TR units, and they fit. It lasted a
> much longer time (years!) before I finally broke that one. Didn't shear
> teeth, actually, but when I disassembled it to repair the No-Spin I
> a couple of teeth were half-gone so a fellow Spitfire racer had a spare
> I talked him into selling it to me. Since then, last year I bought a
> more spares from Mr. Kipping. (The No-Spin, BTW, was unrepairable, so now
> I'm running a welded rear).