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Peter Scott
United Kingdom
1240 Posts |
 Posted - 16/04/2005 : 18:41:48
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I understand that oil in the rear brake drums is a common feature of MMM cars. However the amount of oil getting into my drums is more than acceptable. There are two seals in the PA rear axle hubs. The hub seal (metal and neoprene lip seal) The other the axle shaft seal which I understand may be Cork PTFE lined / Nylatron or Brass.
I assume that the hub seal is designed to prevent bearing grease from leaking into the drums and the axle shaft seal is designed to prevent diff oil from entering the brake drum. Is this correct? Would replacement of the axle shaft seals address the problem or are there other issue I need to consider. Which type ie material is the best for this component.
Peter |
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Bob Clare
United Kingdom
278 Posts |
Posted - 16/04/2005 : 21:42:42
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Peter,
No doubt others will comment, but on PA 1048 I tried the cork neoprene scrolls on the half shafts but they proved useless. The other option is to use brass scrolls as fitted to the TA.
However, there are two solutions which I have found useful. The first is to counterbore the ends of the axle casing and fit lip seals to go around the half shafts. The second is to AVOID OVER-FILLING the diff. I run mine with the oil about an eighth to a quarter of an inch above the lower mark on the dip-stick.
Finally - just check the little hole drilled on the top of the right side axle casing about half way out and make sure it's not blocked. It is there to allow for expansion when the axle gets warm. Mine was blocked with paint when I was advised to check it.
Hope that helps.
Bob Clare |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 17/04/2005 : 09:43:16
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Bob
Thanks for our response. After posting my query, I found the previous forum discussion (2003/2004). I have printed it out and studied all the views expressed. I have also made a sketch of an assembled hub as it is not easy to visualise the paths which the oil may take from an exploded diagram.
Where I am now is:
Understanding û The axle seal prevents axle oil getting INTO the inner part of the hub. The bearing seal prevents oil getting OUT of the hub and into the brake drum. The napkin soaks up any oil which escapes from inner part of the hub into the outer part.
I like your napkin solution for oil passing along the splines as it retains any leakage out of harms way.
Shaft seal - Most people seem to use a scroll. Vintage and Classic sell either nylatron or brass. Is the nylatron one the one which you found to be unsuccessful?
Sometimes the splines extend inside the scroll and hence need to be filled. What compound would be suitable for filling them? Some form of epoxy I would suspect.
There are additional solutions to the shaft seal problem ie your lip seal inside the axle casing and Roger FurneauxÆs hub nut with integral lip seal and speedi-sleeve.
Bearing seal û In your 2003 response you say that you use the modern lip seal. Is this a direct replacement for the original seal or is machining required to either the axle casing or the bearing carrier?
Does Vintage and Classic supply the bearing lip seal?
Last question relates to sealing the hub flange. Do you use a sealer rather than a gasket? If so what sealer do you use?
Peter |
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Bob Clare
United Kingdom
278 Posts |
Posted - 17/04/2005 : 11:11:25
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Peter,
I'll try to answer your questions in the order you asked:
The axle seal is intended to prevent oil which creeps along the half-shaft from the diff, getting out into the hub-brakedrum assembly. This requires the end of the axle casing to be counter-bored. I get the lip seals from Mike Allison but any supplier will probably do.
Yes, it was the plastic/cork compound type of scroll which I had trouble with if that's what the nylatron ones are though I don't recall having bought scrolls by that name. It was some years ago. If you use the lip seals above and provided your bearings are OK and the shafts don't run excentrically in the casing, you shouldn't need scrolls - they're just belt & braces.
I've not come across the splines up the scroll problem and I haven't the faintest idea what filler to use - sounds dodgy to me but others may know better (hopefully).
The bearing lip seals are the ame diameter as the original felt ones on my cars and again I get those via Mike Allison. I expect Mike Dowley stocks these as well.
I use paper gaskets on the hub to bearing carrier joints. That's only becasue that's what the clearances were designed for. I don't suppose it's that critical and if i were going to use something else it would be standard B&Q silicone sealent.
Hope others respond also since I'm strictly an amateur!
Bob |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 18/04/2005 : 18:29:35
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Roger FurneauxÆs solution for the TA rear axle oil leak ie modified hub nut with integral seal which runs on a stainless steel sleeve.
I noted from the discussion in 2003/04, on the subject of rear axle oil leaks, that Bill Abbott found the Roger Furneaux solution for the TA to work well on his N type. But would it fit a PA? I see that the bearing retaining nut is the same for all MMM cars. However, is the TA half shaft of similar diameter to the PA half shaft ie would the TA stainless steel sleeve fit a PA? If it does, this solution seems to have several advantages: there is no machining required, it utilises a modern lip seal and the lip seal has a good surface on which to run.
Bob û Thanks very much for the answers to my previous questions.
Peter |
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DickMorbey
United Kingdom
3678 Posts |
Posted - 19/04/2005 : 06:51:13
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I have used nylotron bushes in the axle ends and have found them generally fairly effective - the more so when you fit them to the correct side of the axle, as I discovered to my cost when, at first, oil was being scrolled out of the axle shaft rather than back into it!
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Peter Green
United Kingdom
1682 Posts |
Posted - 19/04/2005 : 09:11:24
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Peter,
The TA half shaft is the same diameter as all Triple-M half shafts except K type, so you should be able to use the nut and sleeve on your car.
I also agree with Bob do not fill the axle to the top mark on the dipstick, I fill to midway between the top and bottom mark on the dip stick.
Peter. |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 19/04/2005 : 09:28:15
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Dick, Peter
Thanks for your input.
So assuming that I do not want to go to the trouble of machining the axle casing, should I try the Nylotron scrolls or the modified hub nut with integral seal? In theory the modified hub nut would appear to be the better solution, but is it so in practice? Or is it just a case of 'suck it and see' what works for you?
Peter |
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Peter Green
United Kingdom
1682 Posts |
Posted - 19/04/2005 : 12:27:10
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Peter,
I have not used the modified nut solution. I use the Nylatron (if that is what they are made from) scrolls they are much better than the cork/PTFE ones. The only problem I have found is that the internal diameter of the axle varies from axle to axle so the OD of the scroll might have to be altered to fit the ID of the axle casing.
Peter. |
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FrankAshleymgm
United Kingdom
115 Posts |
Posted - 19/04/2005 : 18:50:17
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Peter,
Many years ago I suffered with oil in the rear brakedrums on my Morris 8. Fitting new cork scrolls provided an initial cure, but after a few months the problem had returned. Then I read in 'Car Mechanics' that they must be glued into the axle casing to prevent them rotating with the shaft, and thus allowing oil past on the OD. Another set of seals glued with black Bostik and no more leaks. This has worked on various cars, and the last time that I replaced seals (cork/PTFE)on the M-type, I used Evo-stik and have not had a problem since.
Frank |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 19/04/2005 : 19:30:24
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Thank you all for your contribution to this thread. It has proved to be very informative, although I now have votes for:
1. Lip seal in counter-bored axle casing (Bob)
2. Nylatron scrolls û Dick and Peter
3. Cork / PTFE scrolls - Frank
No ones seems to favour the Roger Furneaux solution. This surprises me as it seems like a good engineering solution and requires no machining. Perhaps it is considered to be too complex.
My next step is to pull the half shafts to see what I find and then to pick a solution and try it.
Once again, thanks to you all for your contribution. I am slowly learning what MMM cars are all about. Great fun.
Peter |
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Rodney Collins
United Kingdom
424 Posts |
Posted - 20/04/2005 : 09:37:24
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Peter, Having just been through the same delemer as you I made all the same noises. I took axel to a precision engineering company (they do work for F1) and they felt it would not be adviseable to mill out the axel to fit lip seals as it might make it too weak. So I spoke to Mike at sports an vintage he uses the nylon type seals and also recommended not filling the axel above half. He also told me that the cork type seal are no longer avaliable. Peter Green is right you will have to put them in a lathe as the os diameter will need to be reduced to the size of your axel. I wish I had read the posting about glueing them in! Mine is now all back together so I just hope it all works when I get the car back on the road.
Good luck Rodney
PS I have found T MMM ownership is about lots of fun and a good helping of frustration!! With a lot for help from friends. |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 20/04/2005 : 11:32:34
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Rodney
I not sure that F1 suppliers understand cars with less than 500bhp, so I am not surprised at their comments.
I am leaning towards using the nylatron scrolls as they seem to be the most popular choice and if they are good enough for Mike Dowlan then I guess they are good enougn for me. I do not have a lathe so have to decide how I am going to get them turned down to size. Is it possible to measure that axle and determine the correct size in one go? Or do you need to turn off a bit and try it until it is the right size? I presume that you make it a tight interference fit to prevent it turning.
Like you I am learning rapidily about MMM ownership. My car is on the road but does need several jobs doing to it. Having just bought it I am discovering many things which I want to improve. Now I would like to nail one or two of them so that I can see progress.
You are right it is great fun owning an MMM car even though it can can be a little frustrating at times. However, what strikes me most of all is how many friendly helpful people there are, who are seemingly just waiting to help you.
Good luck with your renovation.
Peter |
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DickMorbey
United Kingdom
3678 Posts |
Posted - 20/04/2005 : 11:54:34
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| Regarding turning the nylotron bushes down to size - I don't have a lathe, but I do have a fine file, and with care I was able to shave material off the outside of the bush until it was a snug interference fit in the axle casing. So far so good! |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 20/04/2005 : 12:26:31
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Dick
I have not yet pulled the half shaft nor seen a scroll so it is difficult for me, as yet to asses the job. However when I do, I suspect that I will arrive at the same conclusion as you. Perhaps mounting it on an arbor and spinning it in the vertical drill might make the job easier. But thanks for your reassurance that the job can be done mannually.
Peter |
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John Reid
United Kingdom
704 Posts |
Posted - 21/04/2005 : 20:35:53
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Peter,
I could help with lathe work, but as has been suggested, if there is not much to remove then it is possible to achieve an acceptable result by hand methods. I guess it is a fitting job rather than machine to a tolerance, so best done with the axle close by.
If you are making your own bushes, there are a wide range of Nylatrons (It's a bit like saying Hoover!), including graphite filled polymers, so you need to make sure you choose the right version. Quite a lot of helpful info available on the internet if you are into technical research.
John |
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