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MG Midget and Sprite Technical - Cures for scroll seal oil leak from transmission?

I'm cross posting this with Triumph Spitfire b/c I realized it's not just Spitfire trannies.

I'm installing a tranny from a 75 SPitfire in my 1976 midget 1500. This has the J-type OD with the scroll seal on the trans front input shaft.
My problem is that, ALTHOUGH NOT INSTALLED IN THE CAR YET, I am getting an occasional oil drip out the front of the bellhousing from the input shaft area of the trans.

Yah yah yah, all the jokes about British cars MUST drip oil, but certainly there are those of you who do not like to leave oil spots on driveways.

Has anyone come up with a practical solution to the scroll seal leak on trannies? I have seen solutions for a scroll seal on rear main engine bearings.

Inputs that I have gotten are the following:
1) Change out the input shaft and install an oil-seal bellhousing from a later trannie -- this is much too much work;

2) Don't park pointing downhill (not acceptable);

3) Someone even stated that he replaced the front gearbox case ball bearing with a shielded bearing (he removed the inner shielding of this new shielded bearing so that oil would still lube the bearing, but kept the outer shielding that separated bellhousing from gearbox in order to keep the oil at bay).
HAS ANYONE TRIED THIS? Can I remove the existing bearing without dismantling the gearbox itself in order to tap out the bearing? Is there a downside to having a one-sided shielded bearing?

4) A local mechanic suggested applying silicone seal to the inside (backside) of the bellhousing, letting it dry, then replacing the bellhousing on the gearbox. Would this really work? Would this cause any damage?

5) Another local mechanic suggested getting a thin 2.5" disc washer with a 1" hole, and positioning this over the input shaft (which is 1" diameter) to form a barrier between the gearbox ball bearing and the back of the bellhousing. WOULD THIS HAVE ANY EFFECT?

Appreciate any and all comments, opinions, and most preferably actual experience in solving the leakiness.

I fixed mine by fitting a ford 5speed gearbox!!!!
Seriously , I think , to a certain extent, it is a 'feature of the model'
Sorry i cant be any more help

rgds tony
tony boyle

Thanks Tony - 5spd gearbox not an option for this low budget car.
Hard to believe that, after decades of ignenious guys working on these cars, inferiority was accepted as standard.
Gotta be SOMEBODY who figured out a low-cost and easy fix for oil leaks, right?

Where is that guy who worked on a solution?!

Hi again
On the late 1500s there is an oils seal on the midget box so they did fix it, but it is not a retro fit.But that is no help to you with a spit box. I dont know about the spitfire box

good luck

tony boyle

For item 3 strictly speaking you don't want a shielded bearing but a sealed bearing and then remove one seal. Shielded bearings have metal shields which keep dirt out but do allow some passage of lubricant.
David Billington

I did not know that there was a difference between shielded and sealed -- my incorrect assumption and thanks for that info!
So, do you think that removing the seal from the gearbox side of a sealed bearing would solve the leaking?
Secondly, do you think a bearing splitter could be used to pull the bearing out (so that I do not have to disassemble the gearbox to tap the bearing out from inside)?
Lastly, have you ever heard of someone replacing this bearing with a sealed bearing as described?



I can't see any reason why fitting a sealed bearing and removing the gearbox side seal wouldn't improve the situation. I think that to remove the bearing with the input shaft in place would require the type of specialist puller with little pins that slot in between the balls and catch the inner and outer races. I've not dealt with the Triumph box but it looks much the same as contemporary Ford boxes I've dismantled and the usual procedure is to drop the laygear to allow the input shaft to be removed, not a difficult job. Not heard of anyone putting a sealed bearing in this situation but then I've no interest in such things as my Sprite started with an A series box which I replaced with a Ford box.
David Billington

Its a long time ago now that I fitted an overdrive gearbox to my 1500 Midget, but as I recall the input shaft simply removes from the front of the gearbox case, complete with the bearing and input drive gear. You remove the bellhousing and as far as I remember there is just a large shim which retains the bearing and shaft.

But it's possible that I am over simplifying things in my memory and you do have to remove the layshaft as well.

I didn't have any gearbox oil leaks into the bellhousing, so maybe mine was the later gearbox.

This might help. Rather out of date now!


The workshop manual for the spridget shows the Triumph box to be like the Ford box and the dog teeth on the input shaft are larger in diameter than the gear so prevent the input shaft being removed without the laygear being dropped down. IIRC the laygear doesn't need to be removed but the laygear shaft removed to allow it to be dropped, it may need a shorter dummy shaft to be placed in the laygear to keep the rollers in place.
David Billington

You dont need to remove one seal from the bearing, just buy one with only one seal. You can tell the difference by the suffix, RS being one rubber seal and 2RS being two.

T Mason

That must be it then David. As l said, it's a long time ago now. I know it was a pretty simple job, didn't need any special tools.


I had wondered about mentioning that but in my experience one seal bearings are far less common than 2 seals and the seals are easily removed, also if this bearing is like those on the Ford boxes it has an external circlip fitted to the outer race to retain it in place so you would have to designate which side the seal was on relative to the circlip. I've not actually tried to find bearings of a suitable size with external circlip and seals as I don't know the size of the bearing. Regarding RS designation, that varies by maker, many do not use the RS suffix to indicate rubber seals fitted but use other designations instead.
David Billington

Inredible inputs, and big thanks to everyone.

Yes, there is a circlip on the flywheel side of the 2.5" bearing.

It's given me new energy to pull that bearing -- since I've already lost a couple weeks pondering whether and how to do it!

Gripping under the inside lip of the outer race sounds like a great idea. I really am uncertain if a bearing splitter would have enough grip on the circlip groove to pull the bearing out -- and I do not have a bearing splitter either.

I do not want to take the guts out of the gearbox to get at the bearing.

THX again.
Welcome more ideas too, if any come to youse.

I know l got it wrong about simply withdrawing the input shaft without tampering with the gearbox innards - a memory failure. But you don't have to fully dismantle the gearbox.

You withdraw the layshaft which allows the laygear to drop a little and this gives the clearance to remove the input shaft with its bearing and gear. I do remember that as l withdrew the layshaft l "chased" it through with a suitable diameter length of wooden dowel which keeps all the needles from dropping out of the bearing. The Dowel is cut in length so it will drop down inside the box with the laygear.

And yes, the input shaft bearing is grooved for its retaining ring.

David, didnt realise the bearing in question had an external groove (K type as we used to designate them) and from memory I think we may have only made them with two seals. RS was the common designator for rubber seals back then but this has probably changed over the years with different manufacturers and we made one and two sealed variants in great numbers but again things are probably different now as manufacturers try to slim their ranges down.

T Mason

I dont recall a thread about the 1500 tranny leaking even the spitfire box which i assumedwas almost dead on replacment

My guess its just regular wear out part that needs replacing....check for burs

Can a redi sleve fix the problem?
1 Paper

1 Paper,
See attached diagram from MossMotors regarding the 2 types bell housing oil seals.
NOTE: The bell housing is THE SAME for both early and late Spitie trannies -- just the shaft insert (items 14 or 16 in the diagram) differs.

I think the "scroll seal" is just a close-fitting sleeve that has a screw-like groove, much like a rifle barrel. I think this restricts oil flow, but ALSO provides oil flow to lube the shaft in the sleeve.
Hence, the occasional oil drip.

AND, I think since this small oil drip is necessary to lubricate the shaft in the sleeve, even replacing the sleeve insert that is pressed in the bellhousing, will not stop oil getting forward into the bellhousing, and hence dripping onto the ground, as the bellhousing is open to the ground.

Later bell housings used a looser fitting input shaft on the tranny, but had a rubber oil seal that prevented oil from getting through into the bell housing.


I see where your at

Being your in kentucky ive got a friend in louiville that is an occasional member here...i can ask him to drop by and say hello if you like, he is fairly fluent on this type of stuff

1 Paper

I re-read your mention of a Redi-Sleeve. I will look that up.
In regards to someone you know in the Louisville area, yes, I'd gladly hear anyone's ideas.

I presume you have checked that the front cover nose pieces are not interchangeable. You can't simply buy the later type with the oil seal? What does note 18 say about it, as both types have that same number in the drawing.


Hey steve...j sent the word out

1 Paper


I think Prop was either talking about me or Trevor. As for myself, I never had a 1500 Midget nor a Spitfire so I'm no help on the transmission issue. The only thing I can add is that what Prop calls a Redi-Sleeve, I know as a Speedi-Sleeve. Probably kind of a "Kleenex / tissue" issue, but if you don't find Redi with a search, try Speedi.

C R Huff

Thanks charlie

I was thinking trevor, simply cuz i knew you were primarly a 1275 guy and trevor has been around a few 1500s and gets creative fairly often

Yes...speedie sleave is correct, not redie sleave, old age sucks, but with the mind going so fast i hardly ever know its almost out to pasture


Agian thanks for helping with the clarity of my fog

1 Paper

Sorry, I've no experience with the 1500 gearbox, but there are a bunch of 1500 spitfire owners in the local club. I can ask around.
Trevor Jessie

I looked at this further.
YES! BOTH bellhousings for both the older and the later trannies are the same. AND, it is only the "seal inserts" that differ -- although either one can be inserted into either bellhousing.
I have 2 bellhousings, one with scroll seal, the other with the rubber oil seal; however, I only have a scroll gearbox.

The rubber oil seal from a later tranny has an ID that is too big for the scroll seal type tranny's input shaft.
So I went to the local bearing shop and had them size me a rubber oil seal that has the same OD as the later-type's oil seal, BUT with a smaller ID (actually is about 15/16") that fits very snugly (?snuggly?) over the scroll-type tranny's input shaft.

I'll take pix and post when I get around to reassembling.

Worst case is if the rubber oil seal fails, I will have the scroll seal insert machined to accept a rubber oil seal, and will try that -- that should give me both scroll seal action, as well as rubber oil seal action.

The effort to pull the gearbox ball bearing and replace it with a sealed bearing proved too great ... at least for the moment.

I may regret not having done the right thing while I have the whole assembly out of the car, but...

TREVOR -- I posted this same question on 2 Triumph forums, and I have to say I got the most and best responses right here on this one.

That sounds like a better solution with the oil seal as you are not modifying any part of the original gearbox components so it's not irreversible. Where the lip of the new oil seal runs on the shaft, is there a smooth section or does it have the spiral groove? If that is where the groove is you may be able to sleeve over it with one of the Speedi-Sleeves that Prop was thinking of, which could probably be fitted with the input shaft in position.

Update ... although it seels like I'm beating this to death:
1) I was about to install the newly resized lip seal in my later lip-seal insert (in preparation to mount it on my early scroll-seal transmission. BUT, I saw that the 1" extension that sticks forward through the bell housing, and over which the throw-out bearing and carrier center, WAS BROKEN! Yes, somewhere/somehow that extension was fractured off (see attached image of broken insert).
2) So, my fall back is to take my intact scroll-seal bellhousing insert and have the backside machined to fit my new resized lip seal. The scroll insert is virtually identical in many important aspects compared with the later trans' lip seal.
See my attachments showing the comparisons and the measurements.
- The machining should actually be minimal, involving only flattening the radius of the recess in the scroll insert (again, expressed in attached pix).


I guess I can only attach one image per message, so the following pix will be in separate messages.


Image showing comparison of stock and resized lip seals.


Comparison of bell housing inserts: scroll vs lip seal inserts.


Final image showing scroll vs lip seal inserts and explanation of proposed machine work on scroll insert to accommodate an addition seal (a lip seal).


Looks like a good modification that you have finally come up with. Well done!
Remember to centre the new seal before final tightening of the housing piece.

This thread was discussed between 23/07/2017 and 27/07/2017

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