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MG Midget and Sprite Technical - 1275 type 9 propshaft length

Can anyone tell me the overall length of the propshaft needed when fitting a type 9 gearbox to a 1275 engine?

The reason I ask is because I'm fitting a recon type 9 with short input shaft in place of a type 9 with modified long input shaft. When I originally did this conversion I found the long input shaft had not been shortened enough which necessitated an 8mm spacer between bellhousing and back plate. With the long input shaft gearbox I had a persistent oil leak from the rear housing oil seal and when I took the gearbox off it had graunched the rear tailhousing, shredding the oil seal on the way. I would not have thought that the 8mm spacer would make that much difference. I'm wondering if I have a propshaft that has been made too long.

Rob
MG Moneypit

Rob,

I can't help with the length but can see that if the long shaft wasn't shortened enough it could hammer the gearbox rear end if the prop shaft was made to a length intended for a short input shaft gearbox. Some info found online https://www.bearingkits.co.uk/Ford-Type-9-Gearbox-Input-Shaft-Lengths/B12.htm . Maybe you can use that info to work out what shaft length you may need.
David Billington

David, if the prop shaft was 8mm shorter (to accommodate the 8mm spacer I had to use) I suspect it would still be too long. I'm wondering if I was sent a prop shaft for a Morris Minor converted to Type9.

The worn away part of the tail shaft certainly looks more than 8mm deep.

Also, its in a Frogeye so maybe the change in distance as the suspension height changes is different than the later midget.

I found this

https://www.the-wizardsden.com/html/propshaft.html

which has a diagram with dimensions but mine is certainly longer (0.75 inch) if I measure to the approximate same position on mine.

Rob
MG Moneypit

Hi Rob

Just measured my prop shaft and it�s approx 645mm.

Les
Les Robinson

Les, is that the total length from end to end?
Mine is 740mm, if I measure 645mm it takes it 5mm past the fillet radius on the bit that goes into the gearbox.

Rob
MG Moneypit

Rob

It�s as per the diagram showing 650mm ie from joint face on the diff to the gearbox oil seal.
Dimension is approx as bit tricky to measure but in region of 645 - 650�ish mm

Les
Les Robinson

Les, so you measured the gap not the propshaft?
Rob
MG Moneypit

Rob
The propshaft is fitted to the car so all I was able to measure was from the rear flange mounting face where it mates to the diff, up to the seal on the gearbox.
Might be more use if I measured from the flange to the front UJ. Can have a do at this tomorrow if you want, not to sure can see the UJ though.
Les
Les Robinson

Can you see a gap between gearbox and UJ? How much silver coloured finish of the slider part can you see?
Rob
MG Moneypit

Rob. Just measured mine. Car is up on stands. From mating face of rear flange to back of gearbox is 640mm. There is a 5mm length of shiny tube showing between front UJ yoke and oil seal.

Bernie.
b higginson

Rob

My dimensions are:-

Rear mounting flange face to back of gearbox = 645mm
Rear mounting flange face to ctr of UJ = 590mm
Rear mounting flange face to start of shiny tube = 632mm

There will be some discrepancy between mine and Bernie�s dimension as my engine is a 948 and Bernie�s is a 1098 and they have different thickness back plates.

Les
Les Robinson

What effect does the adjustment provided by the engine mount positions have on this? I don't mean on the prop shaft dimensions, but whether there is a problem?
GuyW

Thanks chaps.
I can use 5mm of shinny bit to check mine when I reassemble everything.
With the original setup I didn't have any space in fact as I found out I must have had a negative space which manifested itself in a chewed up rear housing.

Guy. I think there may be an element of this which could be part of the problem. I expect that if I made sure the engine mounts were as far forward as possible (given the limitation that the securing screw for the mount is a loose fit in the hole that secures it) I could get 1mm of extra space. Also, if the gearbox mount was too far back when I originally drilled everything it may be pulling the engine back on its mountings so reducing the available space.

I'll know tomorrow when I put the new clutch plate in and assemble everything.

Rob

MG Moneypit

Rob, I would check also that the front engine brackets aren't bent or distorted, possibly bent backwards a little?
GuyW

Just to close this thread.

Rear mounting flange face to ctr of UJ = 600mm
Rear mounting flange face to start of shiny tube = 640mm

So it looks like mine is 10mm longer in most dimensions.

I hope I don't have to reduce its length!! I'll know when I put eng/box in Frog which should happen today (it's a long frustrating story).

Rob
MG Moneypit

Just out of interest, I measured my MK 1 Sprite one at 700mm centre of yolk to the rear flange.
100mm longer than an adapted T9 one.
GuyW

This thread was discussed between 19/08/2019 and 23/08/2019

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