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Triumph Spitfire - Will a 2.5PI Overdrive gearbox drop sraight into my 1975 spit 1500?

I have located a overdrive gearbox for my spitfire, thing is its out off a 2500 pi i do not know if it will drop into my spit without any major problems. Surely this has been done before. If it will then i will need to locate the shorter prop and brackets as current my gearbox is not overdrive.

Hi Ashley

The 2.5PI gearbox is of a different type to that found on a '75 Spitfire (a single rail Marina type if I recall correctly).

Therefore to get the thing to fit, you'll need a new bell housing, possibly the input flange maybe incompatible- so more research will be reqired here, new gearbox mounts, and most definately a new prop shaft. I am not sure whether a GT6 O/D shaft would be of the correct length- maybe a custom shaft would have to be commisioned? Then there is the speedo drive and calibration which would have to be modified to suit the new installation.

All this is possible, and I don't want to pour cold water on the project, but you may find it easier to find an O/D gearbox from one of the four cylinder Triumphs- preferably a J-type. Higher initial outlay would be compensated by less complication at the installation stage.

Alternatively, fit the 2.5L six cylinder engine as well... all you need to do is add a couple of extra engine mounts, reprofile a section of the sump to clear the cross member, and the lump just drops right in!

Rob Bell

This thread was discussed between 25/12/1999 and 02/01/2000

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