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MG Midget and Sprite Technical - 1098 - 10CC gearbox/flywheel/clutch options

Hi All, I've started work putting together a 1098 10CC engine to use with my Alexander 7 port head, hopefully to have it ready for the MASC track day next year.

I would like to remove the current 948 engine from my Frogeye and try and keep it as complete as possible. At the moment all I have is the 1098 short motor, I have a Morris Minor gearbox spare but the condition is unknown. What parts from the 948/1098/1275 engines can I use on this engine? Are all front plates the same, will the 1275 flywheel fit the 10CC crank.

Does any one have any of these parts, or even a scrap engine I can scavenge for parts.
Andy Barrass

Minor box has plain bearings and is to be avoided; use a 1275 midget one, plenty around, ask me if you can't find one close to home. Why do you want a 1275 flywheel, are you thinking bigger clutch to handle the power increase?
And how 'short' is the 10CC unit, would normally expect it to come with backplate ...
David Smith

10cc flywheel sits flat on the rear face of the flywheel whilst 1275 flywheel slips over the end of the flange. IIRC, PCD of the 10cc flywheel bolts won't fit ANY other model. Stick with it and adapt it to use the Sierra clutch and cover along with a T9 box. Not sure if you are 'allowed' to do this but it is the easiest clutch option on the 1098. You'd need an extra locating dowel pin on the flywheel (3 on Sierra clutch but same PCD)
Backplate from Moggy/10CG won't fit straight away but 10CC/1275 will fit straight away. Frontplate is the same but MAY foul a later A+ cover plate. Use Metro tappet covers with their stronger shapes.
rob multi-sheds thomas

Thanks very much for the info guys, I only have the block and crank at the moment plus a few other bits from my box of Mini stuff.

So if I go for the 10CC flywheel and clutch, the 1275 Midget box will fit, do I need a 1275 back plate, or is the 1098 one the same?

David, I might take you up on the offer of the gearbox.
Andy Barrass

LATE 1098 (ie 10cc) backplate will fit but early 1098 (10cg) crank has narrower flange, so, the 10cc crank flange won't fit through the hole in the early backplate plus the pump cover will not fit since the 10cc and 1275 have larger, repositioned covers. If you can't get a 10cc/1275 backplate then I'd get an alloy one cut from sheet. Might cost £30 for the alloy plus a few hacksaw blades and files.

Hope this makes sense.
rob multi-sheds thomas

Andy,

I've got a 10cc crank in my 1420 fitted with a lightened 948 flywheel and HD 6.25" diaphragm clutch. I've not had any issues with clutch slip so wouldn't see the need for the larger 7.5" diaphragm clutch. Either way a 1098 or 948 flywheel will need some small machining to fit the later diaphragm clutches.
David Billington

Andy, give me a shout sometime, I should be able to fit you up with most of what you need.
Give David a shout on the Box though...

Mark.
Mark T. Boldry

Hi Mark, picked up a 1275 gearbox and backplate, but from searching in the archive I need a 1275 gear lever and the clutch arm as they aren't interchangable with the ones on the smooth gearbox I've got. Can you help out with the bits.

Also will I be able to use the clutch master/slave cylinder from the 948 with the 1100 100CC flywheel?
Andy Barrass

As far as I'm aware, the 948 and 1098 use the same clutch hydraulics. The 1275 slave was different.

If you are using duplex timing gear, you will need to use 2x countersunk screws at the bottom of the frontplate and countersink the holes to suit, unless you have the 1275 version.

As an aside, is you crank cross-drilled? I have a 1098 crank which is, but I'm not sure if they were as standard.
Dave O'Neill 2

Thanks Dave, yes I have two 10CC cranks and both are cross-drilled.
Andy Barrass

This thread was discussed between 21/11/2008 and 28/11/2009

MG Midget and Sprite Technical index

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