Output shaft seal for unknown BMC gearbox

[jnrhacksaw]

I've got a BMC 2.2 fitted with a Morris or Newage mechanical gearbox. There's no name on the castings and I've been unable to find anything similar on the net, see photos below.

 

The output bearing was wrecked and this has worn the seal. The seal appears to be felt or badly decomposed rubber and sits in a deep grove in the seal plate.

 

Where can I get this seal, can it be replaced or do I need to modify the plate to take a modern lipped seal?

 

 

 

[RLWP]

The first step with finding a seal is: Outside diameter, Inside diameter, thickness

 

Richard

[jnrhacksaw]

Ok thats easy enough, is this a felt seal I need?

[RLWP]

Ok thats easy enough, is this a felt seal I need?

 

Not necessarily. If the shaft is in good order, you may be able to fit a modern lip seal.

 

Are you sure the original wasn't a leather seal?

 

Richard

[jnrhacksaw]

Yeah it could be leather,

 

If i use a lip seal do I cut away the face of the seal plate in order to push in the seal?

[RLWP]

Damn - I missed that! No, it was a felt ring that pushed into the groove in the housing.

 

You may be able to adapt the seal carrier to take a modern seal

 

Apologies - I didn't look at your pictures properly

 

Do the measuring at let us know

 

Richard

[jnrhacksaw]

The seal dimensions are:

 

10mm thick

44mm inner

54mm outer

 

I found the mark MM on the castings, does this mean Morris motors?

 

If so is this a vedette gearbox?

[RLWP]

So, 3/8" thick, 1 3/4" bore, 2" OD?

 

it's one of the BMC gearboxes, I'm not sure which one

 

I'll ask our peculiar oil seal man to see what he has

 

Peculiar oil seals, not the man

 

Richard

[Flyboy]

The seal dimensions are:

 

10mm thick

44mm inner

54mm outer

 

I found the mark MM on the castings, does this mean Morris motors?

 

If so is this a vedette gearbox?

I'm pretty certain it's a Vedette gearbox. I believe they were made by Newage.

[bizzard]

If you get stuck for the seal it might be possible to make one which I've done before but not for that gearbox.

Take a length of 'say' Jute washing line and cut a circle from it slightly oversize for the recess in the box. Heat up some thick grease, I recommend Castrol Water pump grease, 'the thick yellow stuff, heat it up in a tin until it runs like oil, dunk the circle of Jute into it and leave to soak until the grease is cold and has solidified again. Dig out your beautiful home made seal and fit it.

Jute washing line might not be the correct size, I only mentioned it for an example and anyhow ''er in doors might complain if she suddenly finds her clothes line too short. Fire proof rope of slightly oversize section might work though treated in the same way.

Edited February 24, 2016 by bizzard

[Bearsteen]

If you get stuck for the seal it might be possible to make one which I've done before but not for that gearbox.

Take a length of 'say' Jute washing line and cut a circle from it slightly oversize for the recess in the box. Heat up some thick grease, I recommend Castrol Water pump grease, 'the thick yellow stuff, heat it up in a tin until it runs like oil, dunk the circle of Jute into it and leave to soak until the grease is cold and has solidified again. Dig out your beautiful home made seal and fit it.

Jute washing line might not be the correct size, I only mentioned it for an example and anyhow ''er in doors might complain if she suddenly finds her clothes line too short. Fire proof rope of slightly oversize section might work though treated in the same way.

 

If I don't have any Castrol Water pump grease available will earwax work?

[bizzard]

 

If I don't have any Castrol Water pump grease available will earwax work?

Yes, if you go and get your ears syringed so that you have enough, or candle grease. Seriously this does work, often better than the makers seal.

[jnrhacksaw]

I've found a felt dust seal for a tractor that looks like it will fit,

 

its dry felt, does it need to be boiled in grease?

[Tony Brooks]

I await other answers but I have always only soaked them in oil.

[RLWP]

I've found a felt dust seal for a tractor that looks like it will fit,

 

its dry felt, does it need to be boiled in grease?

 

No, soak it in oil

 

Well done on finding a felt. Some of the current seals available are of a spongy felt, the original material is quite stiff. You'll know it is OK as you need to push the seal and housing onto the shaft, not just slide it on loosely. I've just been through an episode with an inadequate seal on a Lister

 

Richard

[jnrhacksaw]

That sounds ok as the seal will be a tight fit, its 36mm internal not 44mm

[RLWP]

That sounds ok as the seal will be a tight fit, its 36mm internal not 44mm

 

It won't fit

 

Richard

[bizzard]

A fine squashy seal can be made from wool. A knitted sausage made with a cotton reel, four nails and knitting wool (Corkwork). If you haven't a wooden cotton real a block of wood with a 1/4'' hole drilled through it will do fine.

[jnrhacksaw]

I'll trim the seal down till it fits. If that doesn't work i'll chew a bit of bark or animal hide till it fits.

 

Or knitt a seal maybe.

[bizzard]

Or an Aldi pork and apple chipolata

[BEngo]

It won't fit

 

Richard

Serious suggestion here. Would not a suitable length of gland packing do? A piece of 12mm x 10 would be ideal but if that were not available I would try a bit of 12 x 12 beaten thinner.

Join at the top? It would need to be suitable for oil, but that's not hard. You would probably have to buy a 10m box length though.

 

N

[bizzard]

I'd thought of that but dismissed the idea because it would be too firm and needs to be compacted to seal like with the gland pusher.

Having said that, tough graphite seals were often used on certain engine components like main bearing blocks and sump end seals, but it was always slightly oversize and squeezed when tightening the bearing or sump bolts.

Edited February 26, 2016 by bizzard

[BEngo]

Not all packings are designed to be squeezed by a pusher; though many are, there are some quite 'springy' packings available.

 

Even with a not very squashy packing (and there is only limited 'squash' in felt seals), it should (might?) be possible to pack the housing so that the natural rest position of the packing is with a diameter a little smaller than the shaft nominal, so that the hoop stress in the packing keeps it against the shaft

 

Can't cost a fortune to try!

 

N

[bizzard]

Not all packings are designed to be squeezed by a pusher; though many are, there are some quite 'springy' packings available.

 

Even with a not very squashy packing (and there is only limited 'squash' in felt seals), it should (might?) be possible to pack the housing so that the natural rest position of the packing is with a diameter a little smaller than the shaft nominal, so that the hoop stress in the packing keeps it against the shaft

 

Can't cost a fortune to try!

 

N

Yes quite, only a lot of labour.

[bizzard]

How about making a miniature silicon rubber innertube with a tiny valve sticking out. It could be then easily inserted into the recess in the flaccid state, the casing replace over the shaft and then the innertube inflated at the little valve to a nice sealing pressure, I'd reckon to about 5 psi.