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Dedicated to the memory of the late Brian Archer who fulfilled his dream to re-create John Sprinzel's Sebring Sprite Coupé

 

Toyota T50 Gearbox Conversion

Derek Stewart, who has a later T50 in his Sebring, has done some research into the conversion's history and tells me it was first available around 1985/6 and retailed in the UK by the Morris Minor Centre Ltd (originally Bath, now Bristol) and by Minor Mania of London NW7. Dellow Conversions, in Australia, was the manufacturer and their retail outlet appears to have been via Rooster Racing. Both Minor Mania's and Morris Minor Centre's fitting instructions are shown opposite. Derek discovered that the supply of bell-housings stopped for two reasons: gearboxes started to become thin on the ground and, the minimum bell-housing order was 50. Morris Minor Ctre used to supply Frontline (just down the road at the time) with their components for the conversion applicable to Spridgets and when the source of bell-housings dried up, Frontline made an adapter to mate the Toyota bellhousing to the 'A' series engine. Donor 'boxes are no longer easy to find (although there have been a couple on ebay recently) - the T50 was fitted, in various forms, to Corolla, Carina, Corona and Celica models between 1975 and 1987. It normally had the following gear ratios (compared with those of a 1275 Sprite/Midget):

GEAR
TOYOTA
BMC
First
3.587 : 1
3.2 : 1
Second
2.022 : 1
1.916 : 1
Third
1.384 : 1
1.357 : 1
Fourth
1.00 : 1
1.00 : 1
Fifth
0.861 : 1
-


So, really very similar ratios - in fact those of the Toyota box are slightly closer and the 5th gear acts as an overdrive for cruising. Quaife did offer a closer ratio set which may still be available (?). All the T50 boxes have a 21 (?) spline input shaft but early versions had 20 splines on the output while later ones had 22. Hence it is important when buying a gearbox to obtain the yoke from the original prop shaft to enable you to get the right hybrid prop made up. Another variation is the position of the gear lever relative to the front of the gearbox - later ones are 10 cms further back and better suited to the Sprite being about 3.5 cms back from the original location, earlier (Celica) boxes having the gear stick about 6.5 cms forward of the normal Sprite position.

The first thing I noticed about the Toyota box was that the input shaft was quite short and, on checking, discovered that the spigot would not reach the phosphor-bronze bush in the end of the Sprite crankshaft. I soon learned that the kit should have included a machined boss to fit in, or on, the flywheel which would house a 12mm internal diameter roller bearing. On subsequent enquiry I discovered that the missing item had remained with the engine of the Morris Minor to which it had once been fitted. Fortunately my friend Paul Smith of Paul Smith Precision Engineering soon made one up for me, and supplied longer bolts for the boss and flywheel - problem solved.

I acquired a new gearbox mounting from Australia - £86 in total - from www.onautos.com.au see photo opposite, and an angle-drive for the speedo cable (£95) from Speedy Cables.

A very useful link below gives all the information required to dismantle and re-build a T50 gearbox including details such as replacement of the reverse light switch, or removal of the speedo drive:
http://forums.club4ag.com/zerothread?id=9626

Hello Martin,
I was interested that you are fitting a Toyota Gearbox to JJO. I fitted that same conversion to my Frogeye some years ago and it has been successful. I did find that the engine had to be tilted over slightly and a steady bar fitted to ensure that touching and vibration was not an issue. Apparently there are some different versions of the gearbox and the one I have did not entail altering the gearstick opening at all with the gearstick in the original position.
Regards, Pete (Taylor) 22 Apr, 2014.

Sorry this page is not yet complete - more to come shortly

Toyota BoxToyota Parts Overstock.comMinor ManiaMinor Mania Fitting Instructions, etc.T50 instructions
Morris Minor Centre
Fitting InstructionsToyota T50
My early T50 gearbox with BMC adaptor bell-housing.
Flywheel boss
Flywheel centre boss with spigot bearing.T50 rear mounting
Rear mounting