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Fitting A 998 Gearbox To A 1275


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#1 mrmerci

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Posted 08 September 2019 - 10:59 AM

Hi guys, I've got a problem with the gearbox on my 1275 and was thinking about swapping it to a 998 gearbox while I rebuild the original box. 

As I understand it, the 998 should fit if both boxes are A+, which they are. I've heard things about needing a different primary gear, is it a difficult job to swap this gear for the one I've got on the 1275 box?

thanks



#2 nicklouse

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Posted 08 September 2019 - 11:04 AM

the primary gear is the one on the crank. but the drop gears must match. the final drive from the 998 box may not be the same. the idler gear may not be correct as the A+ engine had early and later drop gear gearboxes fitted.



#3 mrmerci

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Posted 08 September 2019 - 11:08 AM

so will I need the full set of drop gears? Presumably I've got these in the 1275 gearbox on the car already? I'm not too worried about the final drive, because its only temporary until I get my 1275 box rebuilt. 



#4 Ethel

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Posted 08 September 2019 - 01:23 PM

The gearboxes are essentially the same. Unless one has a more suitable set of ratios go with which is in the best condition.

The primary gear needs to run within tolerances on the crank, so the one that's already been mated with it is likely be best, it's still worth checking.

It's the idler gear bearings that differ, with A+ being bigger than the A type.

So you need a full set of 1275 transfer gears that match the gearbox casing in terms of A or A+. There are bushes to fit an A idler to a A+ casing, but I can't see any reason you'd want to.

I'd be inclined to get the box off the 998 up to scratch so you only have to do the job once



#5 mrmerci

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Posted 09 September 2019 - 11:54 AM

Thanks ethel, both boxes are A+ so i think it should be a straight forward swap. My plan is to swap to the 998 box for a bit while i get my 1275 box reconditioned. The car is my daily so I need it on the road. I'm wanting to use the original box because the car is an '85 Metro 1.3HLE (dont hate me, i know its not a mini) and I think keeping the HLE part of the car is important, even if it is painfully slow...



#6 nicklouse

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Posted 09 September 2019 - 12:52 PM

I love the confidence that both boxes are A+ there is really no such thing. Rod type boxes came in both types.

 

but if case numbers are the same then no issues.



#7 Ethel

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Posted 09 September 2019 - 12:57 PM

Nothing wrong with a Metro. I don't know if the ratios were different to the 998 E Minis, but the final drive was the same.               

 

I'd be pretty sure they'd all be A+ by the mid 80's. There's the triangle of bolt holes for a Metro engine mounting on the rear of the transfer housing. I can't imagine any of those were machined for pre A+ idlers but some might have got earlier gear sets to go in  end of run models. Like the legendary 1098 "A+" Clubby estates.    



#8 MiniMadRacer

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Posted 09 September 2019 - 02:11 PM

Not sure if it helps but my Pickup 998 A+ is 1981 and it seems to be a bitza.... of course.. I have no idea who may have fannyed with it before I bought it, but its a very early A+ 998 lump and it would appear they threw any old "crap" in it that was left on the production line for the 998's. Clearly this may not be true of the 1275's. I think you really need to check what you have as the A to A+ change over on gearboxes / transfer cases at least was not clear cut :-)



#9 MiniMadRacer

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Posted 09 September 2019 - 02:14 PM

by the way I loved mettys I had a 998 a MG metro and a MG Metro turbo... all good motors for the "era"






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