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MG Midget and Sprite Technical - Gearbox types / options

My Midget is a 66 but a PO has fitted a 1275 engine . I am looking at getting a gearbox rebuilt over the winter and I have two options. I have one out of a 1971 1275 and the one in the car which I assume is from the 1098 . Are there material differences I know the gear levers are different are they interchangeable? Is there any benefit of getting one done over the other ? Thanks
Mike Fairclough

Mike

Late 1098 and 1275 gearboxes were identical. Earlier 1098 gearboxes had 'A'-type gears, which are not interchangeable with the later 'B'-type.

I believe that parts are more available for the later gearboxes.

AFAIK the gearlevers should be interchangeable, although it's easy enough to swap the remote housing if they are different.

Given the age of your car, there's probably a good chance that it doesn't have the original 'box anyway.

I can have a look at your spare 'box if you like and see what state it's in.
Dave O'Neill 2

Cheers Dave , don’t know much about gearboxes so frightened to look inside , but you’re welcome! I know the shaft is a bit wobbly. Is there a serial number visible on the outside of the box I could check the one that’s in the car ?
Mike Fairclough

There should be a number stamped on the left hand side of the 'box, although I don't know if there is any information available that would identify what it is.
Dave O'Neill 2

The spare box I have on the bench has 22g1117 stamped on the shaft behind the release bearing , quick google seems to suggest that could be correct but there is play in that shaft and the output shaft too so I assume it will at least need bearings
Mike Fairclough

Mike,

There will be some play in the input and output shaft as there is only one deep groove ball bearing on each shaft for support when out of the vehicle, and the small bearing between the 2 shafts.
David Billington

I make a roller clutch release bearing for 1275’s when using a stock clutch. I have been busy in the garage today making another batch to keep up with demand.
No modifications reqd just fit & forget.
alan dot anstead at btopenworld dot com.




Alan Anstead

Mike, if you're looking for a 'local' gearbox renovator l had mine rebuilt by Klassik Transmissions in Wolverhampton. Excellent service and prices. That was in 2009; no problems since just regular oil changes. No connection with them, just a shout out for a job well done. Dave
David Cox

Thanks for the replies , the three Dave/David’s ! Good to know that the shaft wobble might not be too bad. I will have a look at Klassic transmissions if I decide to go for a rebuild . Alan I’ll drop you a message .
Mike Fairclough

Mike
The usual input shaft (1st motion) on a 1275 box is stamped 22g229 but it seems the 22g1117 was also used but I don't know when (might be a replacement part number). Others may know. You don't want anything else with a 1275 imv. The oil needs to be 30 weight or 20/50 engine oil, not the thicker stuff.
Bill B

All the B-type 'boxes I've ever had have had the 22G229 shaft. A-type have 22G172, as opposed to Minor's 22G171.

I've never seen a 22G1117, although it would seem to go well with 22G1100 laygear, 22G1118/9 1st gear, etc.
Dave O'Neill 2

David Cox,

Same here for Klassik Transmissions in Wolverhampton http://www.klassiktrans.co.uk/

They rebuilt my gearbox, tbh they lost money on it cos is was so bad
Malc Gilliver

This thread was discussed between 29/07/2025 and 31/07/2025

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