REAR AXLE HUB OIL SEAL

[i lovemylcv]

Hi I need to replace the oil seal inside the rear hub on the back axle as it, I suspect, causing oil to leak onto the rear brake shoes. I have got as far as removing the half shaft then to that big nut. The question is that big nut needs to be undone but which way does it undo, does it undo clockwise or anti clockwise. I am sure someone in the club will know, Thanks for your help and look forward to a reply. PS That is all it needs to obtain its new MOT

[philthehill]

Which rear hub is leaking Near Side (passenger) or Off Side (driver)?

[bmcecosse]

The natural rotation of the hub tends to tighten the nut...so as Phil asks - it depends which side! But - why is the seal leaking - is the bearing 'wobbly' . is the axle breather clean, is the axle overfilled.

[aupickup]

so passenger side undoes to the right hand and drivers undoes to the left, am sure thats right

[i lovemylcv]

Thanks all so far. the faulty oil seal is on the rear nearside, so from your replies so far I need to undo the big nut clockwise but before that I will check the breather outlet on the axle case that is something I have overlooked so thanks for that advice. So fare , I have checked the oil level and that seems ok, I have no wobble on the wheel and the wheel bearing seems ok, but you can not see what it is like until you remove that big nut. At the moment oil is getting into the brake drum so I think it must be the oil seal. any other advice or comments welcome.

[alexandermclaren]

Thanks all so far. the faulty oil seal is on the rear nearside, so from your replies so far I need to undo the big nut clockwise but before that I will check the breather outlet on the axle case that is something I have overlooked so thanks for that advice. So fare , I have checked the oil level and that seems ok, I have no wobble on the wheel and the wheel bearing seems ok, but you can not see what it is like until you remove that big nut. At the moment oil is getting into the brake drum so I think it must be the oil seal. any other advice or comments welcome.

I had a similar problem with oil leaking into the drum, and this was with all new seals recently fitted,it turnsout I had inadvertently fitted the new seal back to front,so watch out how you fit the replacement seal . I am sure Phill will be able to tell you the correct way round it goes , as I am still unsure,think the spring side faces the source of the oil containment,I . E towards the diff

[alexandermclaren]

Thanks all so far. the faulty oil seal is on the rear nearside, so from your replies so far I need to undo the big nut clockwise but before that I will check the breather outlet on the axle case that is something I have overlooked so thanks for that advice. So fare , I have checked the oil level and that seems ok, I have no wobble on the wheel and the wheel bearing seems ok, but you can not see what it is like until you remove that big nut. At the moment oil is getting into the brake drum so I think it must be the oil seal. any other advice or comments welcome.

I had a similar problem with oil leaking into the drum, and this was with all new seals recently fitted,it turnsout I had inadvertently fitted the new seal back to front,so watch out how you fit the replacement seal . I am sure Phill will be able to tell you the correct way round it goes , as I am still unsure,think the spring side faces the source of the oil containment,I . E towards the diff

[i lovemylcv]

Thanks, that's a good point should the new seal be placed with the spring side facing the diff or to the outer?

[philthehill]

As it is the near side the large nut should be undone clockwise.
As regards the seal the spring side of the seal should be towards the bearing and oil source. Pack the spring side of the seal with grease after fitting and lightly smear some oil on the seal lip. Make sure that the seal lip rubbing surface on the axle tube is clean.
Make sure that the half-shaft is allowed to go fully home against the hub and the mating faces are clean. If you have washed out the bearing - flood the bearing with EP90 or smoother in GP grease before fitting. The bearing should stand proud of the hub face approx. 0.004" so as to allow the bearing to be gripped. Replace and grease the large 'O' ring (Pt No: ATA7225) if fitted (hub should have a machined groove/recess for it if fitted) and grease the gasket (Pt No: GFG110) before fitting. Replace the lock washer/tab (Pt No: 2A7250) and refit and tighten the hub nut (no torque figure quoted in the BMC manual) up very tight taking care not to get it crossed threaded. Make sure that the half-shaft locating screw (MOSS Pt No: SF604051) is fully home & not proud of the half-shaft.

[i lovemylcv]

Thanks all for your advice, Job Done, I now have a new MOT! Its great having a Minor, Interesting, great fun, and very positive and friendly advice from other owners who care and know what they are talking about.

[Ufudu]

I have just replaced the rear seal (it was hard & brittle) & bearing.

What torque do you suggest for the big nut? Philthehill suggests very tight but can anyone suggest a number?

40 lb/ft ? 60? or is that too much?

I would not want to strip the nut.

thanks

Erwin

[philthehill]

There is no torque figure given in the BMC wksp manual section HH2 it just says 'tighten the nut' so just do up very tight and lock with the tab washer.
I use the correct socket (which has been ground down on the nut face to ensure that the narrow hub nut gets all the contact/pressure required) and a 1/2" x 14" breaker bar. The load I can impose is more than adequate and I never feel that I am going to strip the thread but of course care is required as irreparable damage can be caused to the end of the axle tube.

[Ufudu]

Thanks, interestingly I tightened the nut using the same tool I used to loosen it, trying to get the same "feel" as when loosening ... then used a torque wrench to try "measure" the equivalent torque... I got to 110Nm and gave up, the nut was not moving further.

Seems tight enough but I guess there is no "give" in the bearing so there will be no further movement of the nut anyway?

Erwin

[philthehill]

Whilst the nut is thin the thread has a lot of load bearing surface between it and the threads on the axle tube so will with normal tools and no gorilla tactics be difficult to strip. More chance of getting it crossed threaded

[M25VAN]

Don't forget to check that the little drain hole in the brake backplate is clear. This could ave your shoes if you get a leak in the future..

[John159]

Having the same problem now . All the posts have been very useful re how to tackle the problem. Long may the enthuasist of all the MM posters continue. Just three comments / suggestions and would appreciate any views on them:-

(1) it might be useful if someone could put up an explosion diagram of the sequence of the various parts While clearly showing what is the seal and what is the gasket - as they are ' both round and have a hole in the middle for the axle'. My C skills do not go that far.

(2) when I removed the brake drum , oil and that single screw that is exposed when the drum is removed oil started to drip from underneath . I always assumed that this single screw was to assist in prising off the brake drum when it is screwed anti clockwise near side and clockwise on offside. Now I think it's purpose is to secure the outer extremely of the axle to the flange and when it is unscrewed oil can leak out - hence the oil drops Which I experienced. But why only one screw if that is its purpose?
(3) re filling the back axle. Should it be filled up to the level of the opening or , for EG , an inch below it. I filled mine up to the top recently and I have noticed a renewed fresh spattering of oil on the undercarriage. I suspect The driveshaft - where it connects to the back axle might need a new seal

[philthehill]

Diagram attached:-

The single screw (item No: 37) holding the half-shaft (item No: 36) to the hub (item No: 38) is only to hold the half- shaft to the hub prior to the drum (item No: 46) and wheel being fitted. The four wheel nuts hold it all together. Later hubs were fitted with a 'O' ring between the hub and the gasket (item No: 45) (Diagrams attached).
It is normal for a small amount of oil to escape between hub and half-shaft when the screw (item No: 37) is undone.
The axle should be filled to the bottom of the filler hole (i.e. fill till the oil runs out and then let it run till the oil runs no more).
It sounds like the pinion seal needs to be replaced if you have oil at the front/nose of the diff.[frame][/frame]

[philthehill]

[frame][/frame]

[John159]

Response much appreciated-Philthehill

[John Naylor]

Don't forget to check that the little drain hole in the brake backplate is clear. This could Save your shoes if you get a leak in the future..

I agree and I think this should be emphasised! If the hole is kept clear you will see oil stains appearing on the inside of the rear wheels long before your linings are ruined.
John