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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Alternative Gearbox

I fitted a Ford Type 9 five speed gear box to my 1954 MG TF some time ago. These gearboxes were available at the time in scrap yards for 20 but are now 500. Whilst I found the fifth gear to be usefull the major advantages were lack of noise and a syncronised first gear. I do find my Sprite's 'box howls in first gear and is a nuisance when approaching a T junction or traffic lights. I note 1500 midgets have a fully synconised Triumph box and wonder if this is fitted Morris Maina 1275 cars. If this is so could a 1275 Sprite be fitted with one of theses? So no fifth gear but hopefully less noise and a syncronised first.

Jan T
J Targosz

IIRC there is or was a direct bellhousing conversion to do this made by a racing company, last time I tried to find it I couldn't, but it allowed the stronger Triumph box to be easily fitted. I don't think you can use the Marina bellhousing as it's an enormous lump and won't fit. The other option some have used is the A series to type 9 bellhousing and a type9 to Triumph adapter, IIRC someone who posts here has a web page detailing it.
David Billington

There is a detailed article here about putting a Mazda MX5 gearbox in a Midget. It sounds like it might be easier to find a way to fit the Triumph box...

https://www.wheels-alive.co.uk/classic-austin-healey-mg-upgrade-installing-a-mazda-mx-5-gearbox-in-a-sprite-or-midget/
Jonathan Severn

There a thread in the Technical section where an MX-5 box was fitted by a poster, at the time, on here.

If fitting a Triumph box could you also add an overdrive?
Nigel Atkins

I know someone that fitted a BMW gearbox but, apparently, it took a lot of machining.
Several Midget 1500 owners have fitted overdrive.
BGH Geartech were considering having T9 casings re-cast due to the popularity of the T9 gearbox. Both my 948 Frogeye and 1275 Sebring rep have T9 gearboxes the 948 with my homemade bellhousing. Of course both have my clutch release bearings.
I recently made a custom clutch release bearing for someone who frequents this site and was doing a T9 conversion.
There was a Co fitting the MX5 to the MGB with the idea of fitting the same to a Midget but I have not heard if the concept progressed.






Alan Anstead

My Type 9 cost £50 and later I bought a spare for the same amount. A few years later I sold it for £160 and thought I’d done well, should have kept it! Why have the parts of these cars quadrupled in price but the cars themselves haven’t even doubled!!

I’ve now got one car with a Type 9 and one with the original rib case. I like both of them but I suppose I have to admit the Type 9 is a superb box and I miss the extra gear in the rib case car. Strangely I like the lack of synchro on first, something really nice about having to double de clutch!!

The MX5 option could be worth looking into but I still wouldn’t discount the Type 9 even at today’s prices.
John Payne

Be quick ot it'll go.

"Good working order".

275 quid. Collection suffolk. Send a courier if not close enough, but probably worth the petrol money to collect.

https://www.ebay.co.uk/itm/284255252853?hash=item422eeef175%3Ag%3A~8wAAOSwrhpgdLmN&LH_ItemCondition=3000
anamnesis

There is a Kent Masc member with a Mk2 Sprite who has fitted a 6-Speed Quaife sequential gearbox however it is mated to a Ford Zetec enginge.

After converting a Tifosi Rana (Midget 1500 looking like a Frogeye) for someone with a T9 in 'good working order' the gearbox was found to sound like a 'bag-o-nails'. The gearbox was replaced by one from BGH Geartech. Unfortunately a selector was then rubbing but that led to a plan to have the gearbox rectified so that I, with assistance from John Clark, could then fit it at the Practical Classics show NEC.
The situation and timing explained ( the original plan was for me to fit a gearbox to a Frogeye but two weeks before the show the owner withdrew his car ) BGH were brilliant not just rectifying the box but at short notice giving a five hour masterclass in rebuilding the whole box when a new selector would have sufficed - and as warranty.

I fitted the T9 at NEC.

Then on the way home the HG blew! Another job!



Alan Anstead

If my rib case howls in first and roars on the over run, even in top, what's likely to be wrong? If it is just worn bearings it will not be too expensive but if gears are worn, a new lay shaft and first gear will push the cost up significantly. The howling in first could be bearings and lay shaft spindle but the noise on the over run worries me. Since this is a direct drive I fear the centre roller bearing is at fault allowing the main shaft to 'bend' slightly and thus causing misalignment of the two large bearings. A relatively inexpensive fix providing the nose of the first shaft isn't scored! I am not going to take the box out until the Autumn but may try to pick up a spare one at the MG and Triumph Spares Day.

Jan T
J Targosz

Jan,
before buying another box you want to thoroughly check out the rest of the car by regular use and full check over, servicing and maintenance.

And I think you had the right idea to get a knowledgeable Spridget person to say just how much louder your box might be than others and a quick drive and look over the car for they're all like that and any "they all do that".

I know there's (was?) a very active MG lot in Edinburgh but don't know about Glasgow, someone that actually drove/drives a Spridget regularly probably better than someone was a show car (but not always).

Sorry I've not a clue about mechanics, particularly of a gearbox and I know others will know more about sorting gearboxes and the quality of used/recon boxes.

Nigel Atkins

David Billington. I think you mean Antec Motorsport Engineers. I bought a bell housing (maybe from yourself?) years ago. I used it in an A series to type 9 conversion by using an adaptor from Midget 1500 to type 9 from Canley Classics.
Rob





MG Moneypit

Rob,

That's the direct A series to Triumph gearbox bellhousing I was thinking of but a quick search for them turned up nothing so it looks like they're no longer around. You didn't get it from me. I did find them on the internet some years ago when they were previously mentioned here IIRC, possibly by yourself.
David Billington

Jan, unfortunately once you start trying to sort gearboxes out it usually gets expensive.

I had my rib case rebuilt a couple of years ago and that cost £800. It’s still pretty noisy!
John Payne

I got a MM ribcase rebuilt by a specialist and made the mistake of not fitting it for 6 years. When I did it had a noisy first and second gear which has got progressively worse over the last 2 years to the point it's embarrassing to set off in public.
8 years ago there were a lot of unhardened layshafts being sold so maybe this was the problem introduced by the builder.
Rob
MG Moneypit

Jan

I believe the layshaft is a prime candidate for wear - it does take some hammer. But on the over-run, in top, there is no stress on it although it still revolves. Maybe its needle rollers are pretty worn or even breaking up so are contributing to the noise. Trouble is, if there's lateral play in the layshaft and its bearings then that will tend to cause more wear in the gears. It really needs stripping to find out as you probably realise.
Bill Bretherton

Hi Bill,

I have a receipt from 2013 for work carried out on the car. This includes Gear Box Parts - 1 x gasket set £5.35, 2 x Bearings £7.90, 1 x Bearing £4.11 and 1 x Oil Seal £4.75. I am uncertain which bearings were replaced. I suspect the single bearing was the roller between the 1st and 3rd motion shafts but the pair could be either the main shaft or lay gear ones. Looking at the price I suspect the latter. In any event some bearings look to be the originals as with the lay shaft and thrust washers. Looks like a rebuild is needed and I am looking forward to doing this in late Autumn when the weather turns.

Jan T
J Targosz

Jan

Yes, sounds like it's had a cheap, quick job done. From what I've read, you should always change the layshaft, its bearings, 1st and 3rd motion main bearings plus the needle roller between 1st and 3rd motion, sync rings and rear oil seal AT LEAST. The journal at the front end of the 3rd motion shaft tends to wear also - mine was so we used a PB bearing rather than a needle roller one as we thought it would be "gentler" on the journal (new 3rd motion shafts are rare and expensive). I'll soon know how quiet (or noisy) the gearbox is.......
Bill Bretherton

Bill's right. The gearbox was originally designed for the 803cc engine putting out a modest 30 or so BHP. Its been uprated over the years with a stronger case and better synchromesh etc but the size of the laygear bearings and assembly has remained unchanged. Put 65 BHP from a 1275 engine and its operating at its limit.

The key bearings are the needle rollers on the layshaft and spigot bearing on the mainshaft.They always should be changed when doing any work on the gearbox. Peter May sells the correctly hardened layshaft which also wears. The 'roar' on overrun suggests the layshaft has too much end float. The layshaft has two steel thrust washers at either end, the smaller one at the rear is (was?) available in a range of thickness to bring the end float into tolerance.
Rebuilding the box is quite straightforward and a set of all the bearings new layshaft correctly set up plus gaskets etc usually does the trick. Gear wear on 1st/reverse/Laygear due to no synchro also needs checking out but the parts are available. The other wear point are the 'teeth' on the gears which can become rounded off leading to jumping out of gear. The synchro rings also wear which can make selection of 2nd/3rd/top a challenge. Replacements are available but quality can be a problem. The synchro rings are the same as a Mini, indeed the gears excluding 1st motion shaft and reverse are the same as the Mk1 Cooper S.

The other item to replace is the nylon cup at the bottom of the gearstick as it can 'zizz' Moss do an anti zizz kit with all the parts.
Bob Beaumont

One of the biggest problems with the gearbox is lack of regular oil changes, which is what contributes to layshaft and bearing failure.
Dave O'Neill 2

Can someone confirm that it is not possible to fit a 1500 gearbox into a 1275 using a Marina bellhousing. I find lack of synchro on first a real nuisance and the Ford gearboxes are just too expensive. Also my car has a Heritage shell and I spoke with a guy who sells on eBay Type 9 Kits for a Midget and he explains I would have to cut part of the under tray away. Something I don't want to do.

Jan T
J Targosz

The Marina bell housing is MASSIVE and I believe the starter motor is in a different position when compared to a 1275 Midget.
MG Moneypit

Problem solved! Spoke to Hardy Engineering who have been advertising gear box repairs for as long as I can remember. They have extensive experience of Spridgets and did confirm that the Marina/1500 box is very heavy and is not one of the best. They also said the type 9 is weighty and it is impossible to find one at a reasonable price anymore. They recommend the standard 1275 gearbox with a 3.9 diff but the gearbox needs to be a good one. Many restorers only change bearings but the gears do wear and these cause noise. At one time I was going to rebuild the Sprite's box myself but am now going to get a specialist to do the job. I am not experienced enough to check out gears by simply looking at them and if I did note a problem the cost of replacing gears and possibly the centre shaft would escalate quickly. Best to use someone who has good condition parts on the shelf.

Jan T
J Targosz

Have you seen Daniel Stapleton's book - MG Midget, A-H Sprite high performance Manual - he has a chapter on gearbox options.

A good read, covers most mods to Spridgets - now 3rd edition.

R.
richard b

A good (later perhaps) Spridget gearbox is a joy for feel of the gear shifts IF, IF, it's in good condition. No synchro and bit noisy 1st, no 5th/od, but a joy to shift with 2nd, 3rd and 4th.

Same as the lovely steering feel with the original 3.5" steel hubcap road wheels with 145/80r13 tyres and full sized 15.5" steering wheel, especially the original twin wire spoke, thin rim, steering wheels.
Nigel Atkins

Hello Jan,
It was me that fitted a an MX5 gearbox to a 1971 1275 midget. Whilst it was a bit of a task it was actually a series of smaller jobs with a great many decisions being taken along the way. It is a terrific success and transforms the car. The overdrive top gives great cruising speed but 1/2/3/4 being so close to original gears and super slick synchro makes it a dream to drive. My daughter loves driving it and not being crash first makes it so much easier for her. Needs to teach her double declutching.
Here is the link to go directly to the thread. You can spin a long way down before you see the real work beginning:

http://www.mg-cars.net/mg-midget-sprite-technical-bbs/midget-mx5-5-speed-conversion-2018111206424624933.htm.

The car is currently off the road because I began a small restoration at the beginning of lockdown thinking I would have time on my hands but being a self employed control engineer my work went mental!
And there being no such a thing as a small restoration on a 1971 British car in my experience I ended up taking the floors out and am now really just getting going again.
The MX5 gearbox is cheap and excellent.(MK1 type with sperate remote, later ones are cast in I understand) The total cost of my conversion was less than £300 but that is with me doing the work. I do have an old lathe which proved invaluable in this prototype situation but in truth there is not very much machining required so a machine shop costs would not be great.
If you are coming to Cornwall any time you would be welcome to have a look at mine but unfortunately it will not driving for a while as I have a daughter getting married later this year which is taking up some of my attention.(to keep marital harmony).
I would be happy to provide templates for the adaptor plate and any advice/assistance I can. I contemplated making a CAD file so it can be laser/waterjet cut which would be the way to go if others are interested. I have contacts where I could could get them made but would need to investigate cost but should not be exorbitant.
I made my own hybrid clutch from the MG and Mazda plates so that I did not need to modify the flywheel in case I needed to revert but for a another time I would happily simply machine the flywheel flat and drill to take the MX5 cover-plate which would make things very easy. I made mods to the bellhousing to use the midget clutch release system but would probably go to a concentric release cylinder next time, I was afraid of problems requiring the box to come out to cure.
Apologies for the long-winded post, delighted to be able to assist if required.
I have attached a couple current pics(!!!) but there are many more in the original post.

regards, John






j c macleod

This thread was discussed between 04/06/2021 and 27/06/2021

MG Midget and Sprite Technical index

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