MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

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 - Putting a 1500 Wolseley diff into a frogeye

I would like to put a 1500 Wolseley diff into my frogeye. I believe that it is a 3,7:1 ratio? Is it just a bolt in operation or is there some modification that needs to take place? I also heard that the Wolseley diff casings had no filler plugs and that the earlier type casing and later type diff may not be interchangeable?

Can someone who has done the conversion in there car please give me some advice?
MK DUGMORE

It is a straight swap.

Does your frogeye not have a filler/level plug in the back of the axle? If not, and the Wolseley diff doesn't you can fill it via the breather hole. It takes a bit longer, but it is do-able.

What engine do you have?
Dave O'Neill 2

Thanks Dave

The diff is from a 1956 Wolseley. So that will definitely work?

My frogeye has 2 fillers, one in the axle and one on the crown wheel and pinion housing.

I want to put in a 1275 Marina engine with twin 1,25 SU carbs, the orininal 948 box (or do you think the Marina 4 speed box would be better) and the Wolseley diff.
MK DUGMORE

Are you 100% positive it's a Wolseley diff - if it doesn't have a filler plug then it's almost certainly from a late rubber bumper 1500 midget, same ratio but slightly different housing. My understanding is that all complete A series diffs will go into all Spridget axle casings, but early CWPs cannot be fitted into late diff housings.
David Smith

David, IIRC, but could be wrong, the filler plug omitted when housing was changed to accomodate the greater pinion offset needed for 4.22 and higher. This would make the Wolsely one have no filler.
But on the other hand these earlier higher diffs were different in one respect - the OD of the outer pinion bearing was 2.5", the same as B series, whereas later housings had a smaller bearing. So the filler plug could be a difference.
I have a Wolsely housing here somewhere, if I can remember I'll have a look.
Paul Walbran

The original 948 box won't handle the torque of a 1275. Or rather it will - for a while.

Rob
Rob aka MG Moneypit

They didn't start making the Wolseley 1500 till April 1957 so check it's not a 15/50.
Fergus

@ Paul, thank you I would appreciate that.

@ Rob: So should i try to put the Marina box in then, or what would you suggest. I preferrably dont want to do too much cutting or mofifying at too high a cost. That is why I want to go for the easier and cheaper diff option.

@Fergus: haha that is a problem. I will check up on that and enquire if the axle has a filler plug.
MK DUGMORE

IIRC the Marina bellhousing has the starter motor in a different place to the Frog and might clash with the chassis rail. You would be better off with a 1098 or 1275 Midget gearbox. The 1098 (make sure it is a Midget not a Morris Minor) has a lower first gear (3.76?). 1275 is 3.2 first gear and closer ratios and better suited to the 1275 Marina engine.

Rob
Rob aka MG Moneypit

Hi,


The Marina bellhousing is a huge heavy, cast iron thing as well.


Plus it has a very odd clutch cyl arrangement that perches right on the top and may foul the heater shelf.


Is this an A-plus type block you're proposing to use?


Not sure if the Marina flywheel fits inside the 1098/1275 bellhousing, but someone will know.



Good luck with it all.
Steve Smith Midget 1500

Ah, the flywheel. I believe the bolt holes are the same but the end of the crank is a bit bigger. The centre of the flywheel needs machining out a Tad.

Rob
Rob aka MG Moneypit

IIRC the 948/1098/1275 flywheel is a fairly close fit in the A series bellhousing so I doubt the Marina flywheel would fit as it is quite a bit larger.
David Billington

I should have said the bolt holes in the 1275 Midget flywheel and end of the Marina crank are the same. The Marina crank flange is a bit bigger than the 1275 Midget crank flange so it needs machining out a little.

Rob
Rob aka MG Moneypit

Is there a book with this sort of stuff in it???
Daniel Stapleton

This thread was discussed between 01/11/2016 and 02/11/2016

MG Midget and Sprite Technical index

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