1275cc engine with the Minor 4 Speed gearbox

[jaguar68]

Hi guys,

What's the opinion on a 1275cc A+ engine with a 1098cc gearbox through a 3.9 diff?

Cheers John

[bmcecosse]

Should be fine - but would pull a 3.7 final drive if you can find one.

[jaguar68]

Just found a 3.9 diff on ebay. I've got a 12G940 head and a 276(?) cam to fit. Hope this will be ok

Cheers

John

[bmcecosse]

All (v few exceptions) 1275 engines have the 940 head. 276 cam - should be ok - be sure to get a matching oil pump and a new set of cam followers.

[jaguar68]

What's the super duper 1275 head? The engine was from an Ital.

[bmcecosse]

Well - some models (eg MG Metro) had larger inlet valves - but were still 940 heads!!! The really good head to have is the genuine Cooper S head AEG 163 with larger inlet and exhaust valves. Not inexpensive though.........and prone to cracking between the valves if allowed to overheat.

[IslipMinor]

John,

Although the 1098 box will fit, using the standard 1275 flywheel and clutch, it's a weaker box than the one fitted to the Sprite/Midget. I would be a bit doubtful about its life behind a modified 1275. The 1098 and 1275 boxes look identical, apart from the reverse light switch fitted to the later 1275's, but internally they are quite different. As a bonus the Spridget boxes are also closer ratio than the Minor 1098 - as are the Spridget 1098, which have very similar, stronger, internals. Either of these boxes would be fine with a 1275.

[jaguar68]

Hi Guys,

Thanks for all the advice. The only trouble with going for the Spridget 'box is both the additional cost and also where would you get one from.

The car in question is not intended to be a "racer" or a high speed motorway cruiser. I already have the cam and the other head (as yet unknown, I'll have to get down the garage to identify it) and it would be a pity not to use them. I also have a Ford 5 speed box and the fitting kit, but the varied opinions I got when I aired the possibility of modifying a '56 Splitscreen to fit the Ford box has made me reconsider my options.

Regards

John

[IslipMinor]

John,

Just noticed the litle '+' after the 'A' for the engine - that makes a difference!! You can't fit any of the A-series boxes directly behind it as the clutch cover is too big - don't know about the Type 9, that would be worth looking at.

Would seem that the pairing of the A+ engine and the Type 9 5-spd gearbox would make sense, and then all that remains is which car to put them in!

[bmcecosse]

The method is to use the 1098 flywheel and clutch - drilling the necessary extra holes in the flywheel mounting flange to match the 1275 crankshaft tail. Only the Spridget 1275 flywheel can be used with a 1098/1275 box - all the other 1275 flywheels are too large diameter.

[MarkyB]

The main weaknesses of the Minor box are first (and reverse) gears and the synchromesh into second.
If you don't hammer these the box should work as well as the MG one.

[jaguar68]

Hi Guys,

My '69 four door has the standard 1098cc 'box, will reach 70 mph comfortably, touch an indicated 80-90 before my courage goes and has covered approximately 8000 miles in the last 18 months. I'm aware of the non syncro 1st and reverse gears, and have the correct gearbox mounting plate to mate the 1275 A+ engine to the Minor 'box, as well as the modified, drilled flywheel.

I was almost "blackballed" by some when I dared to suggest fitting the Ford box to the splitscreen!!

Cheers

John

[rayofleamington]

Hi John

I was almost "blackballed" by some when I dared to suggest fitting the Ford box to the splitscreen!!

This seems a bit daft! You've changed the engine and gearbox anyway, so it's a bit mad for people to worry about you having a 5 speed box.
On the flip side, the Type 9 isn't the best 5 speed conversion - I recently had a splitty with a Toyota 5 speed and the box was 10 times nicer. One of the better features was the lever location in the right place instead of half way down where the original handbrake goes, which is a problem with the Ford box.

[jaguar68]

Some people thought that even thinking about modifying a splitscreen was sacriligious!! The splitscreen was bought as a shell, with a knacked 948 engine and gearbox. When I bought the type 9 box, I didn't realise it needed the 2" cut from the rear of the floor, or the handbrake modifying. The 5 speed will probably be fitted to my '69 4 door, which is my daily driver (hence the 8k in 18 months). The splitscreen is going to be a tastefully modified "old school" style heritage hot rod.

Pity I didn't know about the Toyota gearbox mod earlier

Regards

John

[IslipMinor]

The main weaknesses of the Minor box are first (and reverse) gears and the synchromesh into second.

That is true, but the non-synchro 1st and reverse are common with the 948/1098/1275 Spridget boxes as well, as is the improved baulk ring synchro in the ribcase boxes.

The difference in strength in the Spridget boxes comes from using needle roller bearings for the mainshaft gears, instead of the plain bushes used in all the other versions. They will take the higher power from the Spridget engines more reliably, especially the 1275.

The Toyota 5-spd is superb, but they are now pretty rare, and the conversion kits even more so.