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MG Midget and Sprite Technical - Suzuki Jimney Gearbox

Before I decided to rebuild the Sprites original gear box I looked at 5 Speed options. I have fitted a Ford Type 9 to my MG TF and it is excellent. I did this a few years ago and all thet was required was a new bell housing and propshaft. The Ford gear box cost me £85 and £100 for reconditioning. A Ford box can now cost well over £500 plus a rebuild and there are problems with the gear stick position and cross member on a Spridget.

I then checked out the kit that uses a Suzuki Jimney box. It looks as though no body cuts are needed and the gear shift is well engineered. However a new engine back plate, flywheel, clutch and starter are needed and critically an electronic speedo system. The kit is also very expensive and I am uncertain about the availability of Jimney Gearboxes.

Anyone got views on the subject?

Jan T
J Targosz

I found Facebook Marketplace better for getting these gearboxes. I bought one last year quite cheaply (can't remember exactly but probably £60).
I was going to do the A series + jimny gearbox mod from Barrett before they had finalised the selling price. But when it came out at £2200 I got cold feet. I'm keeping it in case I win the lottery.

Barrett themselves supply gearboxes which would tend to take them of the market so may be one cause for lack of availability.
Rob
MG Moneypit

There's an article in this months midget & Sprite Club Mascot explaining the above Suzuki 5 Speed Conversion, shame its just for the 1275 thou.
Tim Lynam

Maybe if someone contacted him and see if he would be able to offer flywheels to suit the 948 and 1098 engines if provided with the pertinent dimensions to make the new flywheel designs he'd be willing. Is it just 2 flywheels one for the 948 and 1098 small mains, I thought they had the same crank fitting details, and another for the big mains 1098. Would certainly widen the base of potential buyers.
David Billington

Dave
To fit a ribcase to a Frogeye you fit the later thick endplate. Then use an early 1098 flywheel which has the same bolt pcd. Then use a 1098 7.5” spring clutch. It would seem that a custom flywheel would be all that is required for this conversion to suit a 948. I believe James works for Crosswaithe & Gardner so probably simple for him to produce if asked.
Alan
Alan Anstead

Alan,

What's the issue with a ribcase in a 948? I ask as I gave a friend a ribcase out of an Austin A40 Farina I was breaking and we fitted it to her 948 mk2 Sprite to replace the knackered smoothcase and there was never an issue in all the years she owned it. I only subsequently heard you shouldn't do it many years later.
David Billington

Dave
There is no issue. The way I have explained fitting it is how BMC said it should be done.
A friend likes to change engines occasionally between a period Alexander Engineering 948 and a 1098 so following the BMC Special Tuning handbook he is able to swop easily. I also have a 70’s letter from BLMC to me confirming the process to follow for the conversion.
I am part way through assisting another friend fitting a T9, which used a ribcase based bellhousing, to a 948. Just pointing out that Mr Barret’s conversion will probably fit a 948 if the Special Tuning brief is followed but using a custom flywheel.
Alan Anstead

Hi chaps,

I have drawings for a 948 flywheel and producing a 1098 is not an issue either. I also have drawings to produce a Marina / Ital single dowel flywheel. The current backplate will fit small bore engines if a 1275 oil pump cover is used. Small bore covers are smaller.

A revised adaptor is currently in development to suit the 1995 to 2005 G13B gearbox as well which will improve availability of donors.

Cheers

James

J Barratt

James,
Any plans to adapt a 5 speed gearbox for the 1500 Midgets?

Tim
Tim Lynam

I have now bought a Suzuki gearbox, dismantled it, cleaned it, inspected it and rebuilt it. The quality of the Japanese box is superb. All I had to replace were the input/output oil seals and a couple of bearings in the case extention. The only reason for the latter was they were so easy to get to. The case splits horizontally and the main shaft can be simply lifted out. All the gears, including reverse are helical and the synchro rings are large diameter. Unlike the rib case the layshaft is carried in substantial ball races and the main shaft has three bearings. The selectors all engage with a wonderful click. The only downside was a tube of correct sealant for the casing flanges was £30. It is the same stuff Ant Anstead used when he rebuilt the MX5 box on Wheeler Dealers.

I have spoken to James Barratt and hope to try out a converted car in the new year when I visit my daughter in the south of England.

Jan T
J Targosz

This thread was discussed between 03/10/2022 and 02/01/2023

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.