Zero-Five-Two Posted April 23, 2011 Share Posted April 23, 2011 Can anybody out there help me with some advice about the Hub Seals on my Mk1 Militant? Having stripped out the rear brakes I have found that all 4 hubs have been leaking to a greater or lessor degree. The off side rear most one is the worst and has been pouring out, so this will be the first one for the clean up treatment. Not a major problem, I thought, there is a shop on Fleebay advertising new seals at £20 each, so £80 would cover a full set. Now I have got the muck off the hub, and can see what I am doing, I find that the items advertised are not seals as such but sprung glands with little or no oil sealing properties at all. and the ones I have got seem to be OK. The actual sealing of the hub seems to be done by the felt strip inside the surrounding alluminium casting. This felt appears to have shrunk over the years leaving a quarter inch gap which allows the oil to leak out. All I need is a new bit of felt rather than £80 worth of metal gland Can anyone confirm I am thinking along the right lines here? and the important question, where can I get a new felt seal? Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted April 23, 2011 Share Posted April 23, 2011 Can anybody out there help me with some advice about the Hub Seals on my Mk1 Militant? Having stripped out the rear brakes I have found that all 4 hubs have been leaking to a greater or lessor degree. The off side rear most one is the worst and has been pouring out, so this will be the first one for the clean up treatment. Not a major problem, I thought, there is a shop on Fleebay advertising new seals at £20 each, so £80 would cover a full set. Now I have got the muck off the hub, and can see what I am doing, I find that the items advertised are not seals as such but sprung glands with little or no oil sealing properties at all. and the ones I have got seem to be OK. The actual sealing of the hub seems to be done by the felt strip inside the surrounding alluminium casting. This felt appears to have shrunk over the years leaving a quarter inch gap which allows the oil to leak out. All I need is a new bit of felt rather than £80 worth of metal gland Can anyone confirm I am thinking along the right lines here? and the important question, where can I get a new felt seal? Rob, You need good quality oil seal felt, which is usally a dense white material. There is a company in Whitstable ( or nearby), who supply this material. I wanted some felt rings cut out for a similar application, or though, I was able to source the correct part elsewhere, so did not pursue it further with the company. Looks like is a parallel strip with a scarf joint, and has shrunk. As for the bellows gland, these are oil seals in themselves, this type of seal is fitted in final drives on dozers (CAT, etc) and the like and are more reliable than lip seals when working in a harsh enviroment...........so long as the faces are not damaged. Quote Link to comment Share on other sites More sharing options...
Zero-Five-Two Posted April 24, 2011 Author Share Posted April 24, 2011 Thanks for the confirmation of my thinking Richard, I have found a couple of companies whose websites claim to make any size and density of felt seals to order, so they will be getting a call on tuesday morning, and I'll go from there Quote Link to comment Share on other sites More sharing options...
antarmike Posted April 24, 2011 Share Posted April 24, 2011 (edited) Sorry, Rob, but I disagree with your analysis of the situation..... The bellows type seal is called a "Packless gland" and is the principle (well actually the only) oilseal for the rear hub. If is an effective oilseal as previously stated but must be handled with care so as not to damage the bellows or the sealing face. It is my understanding of how the back hub set up works, that the felt stops abrasive dust from the brake linings getting near to the sealing faces of the "packless gland" which would wear excessively should the highly abrasive asbestos dust get out drum the shoes/ drum area, and get into conflict with the packless gland. There should be no oil coming past the packless gland to reach the felt in the first place. and the felt is not designed to stop oil getting onto the brakes. If you look at the front differential. the seal on the input shaft is below oil level in the diff and is sealed only by a packless gland. There is no secondary seal, felt or otherwise, to keep oil in the front diff. If the Packless gland keeps oil in the front diff, the same type of gland in the back hub should contain the oil there also. Is the distance piece in place between the packless gland and the brake shoe carrier. This distance piece preloads the bellows to keep pressure on the gland faces? What is the condition of the distance piece in the hub, next to the bearing? I can't see this in your photograhs, or it it still in place in the top photograph. I can't tell if I am looking at the outer race of the bearing or the distance piece. Have you checked that the Packless gland bellows is the right length and hasn't lost its natural springiness. I.e. if you work out the distance from the Packing piece butting against the brake shoe carrier, to the Packing piece by the hub bearing, when the hub is in place, is the packless gland noticeably longer than this dimension that so that it will be compressed as reasonable distance, to provide definite spring pressure? In the Matador rear hub, with which I am more familiar there is actually a spring wound round the outside of the bellows.. Does your manual/ parts book give any indication whether the Militant Packless gland should have a spring around the bellows, I can't see one in your photographs. It sounds to me as if you do need to change the packless gland and the associated distance piece onto which the sealing face rubs in order to achieve a good oil seal.... Edited April 25, 2011 by antarmike Removing ambiguity Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted April 24, 2011 Share Posted April 24, 2011 Sorry but I disagree with the above analysis of the situation..... The bellows type seal is called a "Packless gland" and is the primary oilseal for the rear hub. If is an effective oilseal as previously stated but must be handled with care so as not to damage the bellows or the sealing face. Mike, I did not suggest the felt was an "oil seal", but did suggest using "oil seal quality felt" to make a new dust excluder ring. You are correct in saying how these bellows seals ( or glands) should be carefully handled, I have had wide experience of them, not only on AEC, but CAT and other vehicles. The Militants in army service had often been axle deep in mud and this would find its way straight in to the brake area, so not only asbestos dust to contend with. Quote Link to comment Share on other sites More sharing options...
antarmike Posted April 24, 2011 Share Posted April 24, 2011 (edited) Mike, I did not suggest the felt was an "oil seal", but did suggest using "oil seal quality felt" to make a new dust excluder ring. You are correct in saying how these bellows seals ( or glands) should be carefully handled, I have had wide experience of them, not only on AEC, but CAT and other vehicles. The Militants in army service had often been axle deep in mud and this would find its way straight in to the brake area, so not only asbestos dust to contend with. Richard, I Know that you understand what is happening in the hub and what the seals do, my comments were in answer to the original post and Rob's analysis of how the seals work contained in that post, which ended "Can anyone confirm I am thinking along the right lines here? " as reproduced below... .... I find that the items advertised are not seals as such but sprung glands with little or no oil sealing properties at all. and the ones I have got seem to be OK. The actual sealing of the hub seems to be done by the felt strip inside the surrounding alluminium casting. This felt appears to have shrunk over the years leaving a quarter inch gap which allows the oil to leak out. All I need is a new bit of felt rather than £80 worth of metal gland Can anyone confirm I am thinking along the right lines here? and the important question, where can I get a new felt seal? I was pointing out that in order to cure the oil leaks I felt he needed to be looking at the packless glands, rather than the felt packing , finding out why the packless glands are not working and replacing them if the defect can be identified....The felt may well need sourcing but it will not stop any oil leak.... Edited April 24, 2011 by antarmike Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted April 24, 2011 Share Posted April 24, 2011 Richard, I Know that you understand what is happening in the hub and what the seals do, my comments were in answer to the original post and Rob's analysis of how the seals work contained in that post, which ended "Can anyone confirm I am thinking along the right lines here? " as reproduced below... OK Mike, thanks. The seal / gland may well be worn, because the felt is not fitting properly. Rob, what is the condition of the mating surface to the bellows gland? If at all scored then this would be cause of leakage. I cannot remember if the bellows gland is supplied with its mating surface as a set, this is how they are supplied for crawler final drives, and sealed together as surfaces are mirror finish. Quote Link to comment Share on other sites More sharing options...
julezee001 Posted April 24, 2011 Share Posted April 24, 2011 The gland seals I've fitted on my Militant didn't have the mating surface supplied with them. I think the two I have changed so far had just lost some of their "spring" allowing oil to seep past. They have remained dry since fitting about 6 years ago. As long as the leak is relatively slow, the oil tends to sit in the wells on the lower brake shoe keeping the friction material dry until the next M.O.T. test in my experience. Jules Quote Link to comment Share on other sites More sharing options...
Zero-Five-Two Posted April 25, 2011 Author Share Posted April 25, 2011 Well! I never intended to start an argument between you two guys ( Mike and Richard) or should I call it a constructive discussion. Either way I appreciate your imput. Felt seal keeping the dirt out rather than keeping the oil in seems obvious now you've mentioned it. To clarify some of the points mentioned, Militant gland does not have a surrounding spring, it is sprung within itself. There is a carrier that fits inside the gland to keep it central on the axle. There is a rubbing plate/distance piece fixed behind the rear bearing. I have just been out to the shed and re checked it all. The brass top of the gland (which you can see in my earlier photo) appears smooth and polished where it has been running against the distance piece. This has a wear mark in it, but looks smooth, and does not appear damaged. The bottom edge of the gland has some sort of number hand engraved into it, and the surface has a machined finish which is quite rough compared to the brass top side. This edge runs against a backing ring which is also a machined finish and again quite rough When fitted together the gland only stands about 2mm proud of the centre carrier which does not give it much to compress, and only provides a ligtht tension on the gland. I think the only sensible answer is to bite the bullet and get both new felt and gland, fit carefully and go from there. At the very worst, as Julezee points out, if a small amount of oil is lost it only runs into the web on the inside of the brake shoe and this can be cleaned out quite easily. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted April 25, 2011 Share Posted April 25, 2011 Well! I never intended to start an argument between you two guys ( Mike and Richard) or should I call it a constructive discussion. Either way I appreciate your imput. When fitted together the gland only stands about 2mm proud of the centre carrier which does not give it much to compress, and only provides a ligtht tension on the gland. No worries, that was constructive discussions As it was around 25 to 30 years ago when I was working on these wagons regularly, the mind dims a bit, but something you have just mentioned has made me think. The bellows spring on the seal may well have settled, because I recall having to change these seals, but not because there was visible damage. You could ask the person who has stock of these seals, to measure them, on the pretext that you want to check they are the correct ones, and if there is significant difference between yours and the new ones, then there is the answer, the spring has settled. Quote Link to comment Share on other sites More sharing options...
Zero-Five-Two Posted April 26, 2011 Author Share Posted April 26, 2011 Thanks Richard. Tried that this afternoon, Ray Trigg is the dealer selling them, he does parts for alsorts of classic/vintage trucks, quite a helpful bloke. New ones maybe a shade bigger, so that could be the problem. Another thing I have checked today, the amount of oil in the hub. The handbook states 1 pint per hub, when filled to the correct level. Mine was well over full. So it may have been the leak was caused by some of the excess oil being forced out. Quote Link to comment Share on other sites More sharing options...
Simon Daymond Posted April 27, 2011 Share Posted April 27, 2011 Hope you get this sorted Rob, mine has a leaking gland as well, so perhaps you could do that that the same time you come to do my brakes ? Quote Link to comment Share on other sites More sharing options...
Zero-Five-Two Posted April 27, 2011 Author Share Posted April 27, 2011 Unfortunately, getting it sorted is taking konger than I wanted. Wage paying work keeps getting in the way. Still, with all the advice etc from the likes of Richard and Antarmike, at least I know I stand a good chance of doing it right. Quote Link to comment Share on other sites More sharing options...
Zero-Five-Two Posted May 10, 2011 Author Share Posted May 10, 2011 New felt dust seals arrived today. Perfect fit as well. Being new they sit a fair bit proud of the housing, so I will need to invent some kind of shoe horn/fitting device to get them over the hub. Shouldn't be too much of a problem. :idea: Quick question for the educated ones amonst us. Should the seal be impregnated with oil or grease prior to fitting, or should I fit it dry? Quote Link to comment Share on other sites More sharing options...
rbrtcrowther Posted May 10, 2011 Share Posted May 10, 2011 Normally soaked in oil before fitting this type of seal i think Quote Link to comment Share on other sites More sharing options...
Zero-Five-Two Posted May 11, 2011 Author Share Posted May 11, 2011 Cheers for that, Rob. Will post more pictures on my resto blog when I start fitting them back together Quote Link to comment Share on other sites More sharing options...
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