Morris Minor Owners Club

Sometime in the distant future (summer) I intend to fit a 1275. I do no motorway driving, the nearest one being 80 miles away, and dont really fancy the idea of a 5 speed Ford box. Has anyone fitted an overdrive?

Lots, but probably not a very popular mod nowadays. I am still in the process of sorting mine out. Alec and Charliemorrisminor have experience of this, and I believe "callyspoy" is being tempted at the moment! Basically you make a hybrid box from the Marina box and a Dolomite overdive box. The input shaft length is the thing which you need to swap from one to the other. Various clearance problems with the transmission tunnel, and the rear gearbox mount needs to move back. Also a custom prop needs making(no real problem). Someone has done an ongoing blog about it which I found on the web, will try to find a link as it addresses all the relevant points. Speedo drive also needs altering. All in all not a job for the faint-hearted, but a very satisfying period mod! I believe you may need to cut sizeable chunks out of the Marina bellhousing to clear the steering rack- perhaps someone could confirm? I am endeavouring to avoid this by using the Dolomite bellhousing and a custom backplate, as the Marina bellhousing is a HUGE beast!

I am happy to pass on any advise.. but if you can not justify a 5 speed I do not know why you would justify an O/D box..

as linear said you do need to cut the bellhousing but i would have thought you would have to do that with any marina gearbox fitting, i do not believe it is a problem with the o/d box.. Calspoy is not looking at the o/d box any more as he has the fiat twin cam fitted.

Yes, I meant the bellhousing bit generally, in case the OP thought a complete Marina lump would just drop in. Problem with starter fouling somewhere as well isn't there? Likewise, not likely to be any justification for the overdrive job other than the sake of being different, but thats what its all about!

Just dont fancy a Ford 5 speed box but am very interested in the possibility of making an overdrive work in the same way that I know that I can get more power and economy from a single carb but will be fitting twins. If it was all about logic I would buy a new Ford. Minors are meant to be fun.

Well said, that man

The MGB gearbox is not very big - and comes with O/D. Has anyone fitted that - to an A series engine. May make more sense of course to just use the engine AND gearbox from an MGB!! But for relaxed running - it's SO much easier to just fit a 3.7 final drive. Only takes an hour or so - absolutely no hassles!
My working life having been filled with engineering hassles - I like to keep it simple now!

Roy how would that perform given where I live and the fact that I drive up Cairngorm on an almost daily basis in winter

You may have to do so in third gear - which is then almost equivalent to normal 4th gear. No great hassle in that! Mine will do genuine 80 in third, and 50 in second!

in which case go for the O/D box there is nothing like flicking a switch on the gear knob and "changing gear" never failed to rise a smile on my face even after 4 years!

as i said before.. any question please ask.. first thing is to get the O/D box just do not get a dolly sprint box the box is not the same and the parts can not be intercahnged.

BMC (the company) built some fancy 5-speed boxes for the later racing Midgets using the 4-speed MGB box as a starting point. Must therefore be possible to get the MGB box hanging on.

Never heard that before - do you have a source Rob? There are 5 speed gear sets for Minis - have been for many many years - sure it wasn't just a Mini set adapted into the A series box ?