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MG Midget and Sprite Technical - Maestro Engine in a Midget

As old subjects are resurrected I thought I would resurrect one of my own.

I'm still tinkering with this and my current thinking is Mazda MX5 5 speed gearbox on an A series engine using a self made alloy adaptor. The adaptor would be an amalgum of a simple alloy plate and the Maestro end plate cut and welded where necessary to retain the Maestro conventional crank seal and rear breather.

To that end I sourced a Mazda MX5 MK1 flywheel and had it machined to fit the crank. The MX5 has 6 equally spaced holes on a 65mm PCD so 5 of them line up with the Maestro crank. The 6th could be offset to coincide with the offset hole in the crank.

The centre hole needs to be enlarged to get the flywheel to sit flat on the crank flange.

A simple modification that any machine shop could handle, except the ****** machine shop I used who did it all from the wrong side of the ********* flywheel.

Anyway, I didn't pay them.

What they did do right has enabled me to mount the flywheel to the crank with 5 bolts as seen in the attached image.

Rob


Rob aka MG Moneypit

Forgot to say it's a 1600 Mk1 flywheel. The 1800 is different.

Rob
Rob aka MG Moneypit

Hmmm... very intesting.

To make sure I understand


A mazda mx5 gearbox, a 1275 engine and a mestro engine back plate

Sounds like a commercial kit for sale in the making

What clutch will you go with

Prop
Prop and the Blackhole Midget

I thought the MX5 gearbox was rather bulky
How does it fit?
Need cut the cross member?
Onno K

Onno, the MX5 box is quite bulky but there is a bit that can be cut off that carries the longitudinal brace the goes between gearbox and back axle in an MX5. It will still need the cross member cutting out and the tunnel spreading somewhat. Not really sized it all yet but expecting the worst.

Prop, can't see any reason to not use the MX5 1600 mk1 clutch.

Just something to keep the grey matter ticking over.

Rob
Rob aka MG Moneypit

Rob if you can pull that off and make.it a commercial kit, id vote for you to be king of new free.scotland

That would be a huge game change esp considering.how many of those gear boxes are laying around....the mx5 orginated in what 1992, 1993 ???? Did mx5 ever come with a 6 speed box, now that would be crazy fun

Prop
Prop and the Blackhole Midget

I think the latest MX5 gearbox is 6 speed but only 6th is OD. 1 to 5 are closer ratios which may be better for a high reving A series rather than standard A series.

I did look at Honda S2000 6 speed gearbox, even got as far as obtaining one as all the figures I have seen give 5 and 6 as both OD gears BUT they forget to include the 1.16 reduction gearing at the back of the gearbox which when included makes only 6th an OD ratio but only about 0.91 to 1.
Honda did this because the S2000 engine revs to 8500+ but the torque output is not that impressive hence the reduction ratio at the back of the box to improve acceleration figures.
The S2000 may be better with the K series Rover engine in a big wheeled midget.

The MX5, on paper looks a better successor to the Ford type 9. I only paid 30 for my MX5 GB as against 150+ for a Type 9 needing a rebuild.

Just ordered another MX5 1600 Mk1 flywheel off ebay, 19 including delivery so the story continues.

Rob


Rob aka MG Moneypit

Rob,
I had a S2000 and my friend still has one, limiter is at 9,000 revs, power band - max torque 7,500 revs, max power 8,300 revs and they don't really pick up until 6,500 rev so their whole set up is about higher revs

I couldn't hear much difference in engine and exhaust notes from 6,500 to 9,000 revs

I do know when I recommended a MX-5 to a mate (can't remember the year but the 6 speed boxes were well established by then) he bought a brand new one and had trouble with the (6-speed) g/box among other things - never recommend anything to people you know as Sod's Law things will go wrong with it, I just said I never recommended a 6 speed which was true

I think the 6-speed box first came out when we had our Mk2 MX-5 (1999-2000) as we travelled to low down in France with the local MX-5 club and one couple used the trip to run in the brand new 6-speed 10th Anniversary special they'd collected the day before
Nigel Atkins

Hi,
This got me thinking...
How about a S2000 engine and gearbox in a Midget...
I am sure it could be made to fit and performance would be fantastic. Performance is great in my Civic Type R which has a detuned version of the engine with only 200bhp redlining at around 8,000. With 240bhp and the extra 1,000+ rpm and the lower weight of a Midget would make it a real beast.
Anyone done it?
Dave
Dave Brown

Dave,

I have certainly see it done, there was an S2000/Midget hybrid for sale at some point. I wonder if I can find the pictures...

Malc.
M Le Chevalier

In fact just google "Midget S2000" its white. Registration JPK 332K

The question I always find myself asking is why? If you want S2000 performance, buy an S2000 not a Midget. But each to their own I suppose.

Malc.
M Le Chevalier

Some interesting engine transplants here http://www.arkleyss.dk/motorconv.htm

Rob
Rob aka MG Moneypit

This thread was discussed between 15/09/2014 and 17/09/2014

MG Midget and Sprite Technical index

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