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Can a 1500 overdrive unit be fitted to a 1275? I know it won't just bolt up, but is it feasible?
 
Atrus said:
Can a 1500 overdrive unit be fitted to a 1275? I know it won't just bolt up, but is it feasible?
Click to expand...

Anything is feasible with enough money, how much have you got?
 
With the Datsun 5 speed and the Spridget rib case gearbox basically the same size, would it be possible retrofit 5 speed components inside a rib case? I admit I don't have a lot of knowledge regarding transmissions, but I've often wondered if it could be done.
 
If you can find the 5 speed out of a mercury merkur xr4ti, that is the same as the Ford Sierra in Europe and they make some stuff for that one to fit into the Midget. There should be some of those in the boneyard. There was also a Toyota Celica 5 speed that could be fitted.
 
Atrus said:
Can a 1500 overdrive unit be fitted to a 1275? I know it won't just bolt up, but is it feasible?
Click to expand...
The overdrive would be difficult to mount to the ribcase box. Cut and spline the shaft, cast new tailshaft housing, etc. This is prohibitive.

jhorton3 said:
With the Datsun 5 speed and the Spridget rib case gearbox basically the same size, would it be possible retrofit 5 speed components inside a rib case?
Click to expand...
The mainshaft and countershaft spacing would have to be exactly the same. The length of the box must be very nearly the same from the front bearing to the rear bearing. Plus there has to be space for the 5th gear behind the rear bearing. That means casting a new output shaft housing. It's almost certain that bearing bosses would have to be welded and machined. All this is prohibitive.

Personally, I like the idea of using a Spitfire 1500 overdrive box mounted to a 1275 Marina engine. The Marina came with the Spitfire gearbox and flywheel, therefore being a bolt-up system, except for the transmission tunnel, which would need enlarging for the overdrive.

The Marina crankshaft was drilled for 6 bolts at 2.5 inch diameter to fit the spitfire flywheel. I suppose a standard Spitfire flywheel could be drilled for 4 bolts to fit the standard 1275 crankshaft. The Marina oil pan was fitted with a lower mounting flange for the Spitfire gearbox. This doesn't sound too hard to fabricate to a standard A-series oil pan.
 
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