Loose hub nut

[CJH]

Shortly after I bought my van we took it on holiday, and after a few days travelling I noticed what I thought was the drumming noise from a worn rear wheel bearing. Over the course of the next few days it rapidly got worse, to the point where the wheel was actually wobbling. I took it to a garage, and we discovered that the NSR hub nut was loose - still had the split pin through the castellated nut, but once that was removed the nut could be turned by hand.

OK, I thought, maybe the previous owner didn't have access to the required socket (44mm?) or a long enough torque wrench to do it up properly. But I know for a fact that the garage I took it to tightened it up to the correct torque - he used the biggest torque wrench I've ever seen, with a bit of scaffold pipe over the end, and was virtually hanging off the end to make the torque wrench click.

But now, maybe 1000 miles later, it's worked loose again. Still held in place with the split pin, so I know the nut hasn't turned, but again it was loose enough to turn by hand.

So how can this happen? If everything is done up tight, and the nut is pinned in place, what is it that's wearing to make it work loose?

[Aidan]

probably the outer bearing breaking up, can happen if the nut is excessively tightened to stop a worn bearing feeling loose, if the inner bearing is already worn then the gap for the spacer is increased so tightening it up at that point drags the hub into the outer bearing, had this happen to me when a helpful garage which shall reamain nameless tightened one up instead of replacing the bearings - damaged the bearing carrier too so be aware when you do the bearings

[infidel]

probably the outer bearing breaking up, can happen if the nut is excessively tightened to stop a worn bearing feeling loose, if the inner bearing is already worn then the gap for the spacer is increased so tightening it up at that point drags the hub into the outer bearing, had this happen to me when a helpful garage which shall reamain nameless tightened one up instead of replacing the bearings - damaged the bearing carrier too so be aware when you do the bearings

what he said.
also, nobody should be putting that kind of torque on a nut.

[CJH]

Right, I'd better take a look at that then. Thanks gents.

[Oldiebut goodie]

probably the outer bearing breaking up, can happen if the nut is excessively tightened to stop a worn bearing feeling loose, if the inner bearing is already worn then the gap for the spacer is increased so tightening it up at that point drags the hub into the outer bearing, had this happen to me when a helpful garage which shall reamain nameless tightened one up instead of replacing the bearings - damaged the bearing carrier too so be aware when you do the bearings

what he said.
also, nobody should be putting that kind of torque on a nut.

Oh yes they should!

Rear hub nut on all T25's - 500 N-m (360 lb-ft) then next split-pin hole - how else are you going to get that force?

[Aidan]

could also be damaged threads on nut or half shaft

[dave friday]

or wear on the hub splines,this happened on my daughters 924 brake drum splines!

[CJH]

Thread revival. I had the hub nut tightened a second time, as a stop-gap because I was about to go away in the van. I promised myself I'd sort this out before going any great distances, but have been sidetracked by an interior refit. Since then it's been fine though, but I feel I'm on borrowed time.

If a bearing has been collapsing as Aidan suggested above, which bits will it have damaged, and will it be easy to tell once I start disassembling? Could the hub need replacing? Can the bearing carrier be reused if the surface has been damaged, or will it need replacing (and where from? Couldn't see one on Brickwerks).

I'm toying with attempting this myself on my drive, but the hub nut torque worries me (I'm not a fat man and I haven't got a scaffold pole!), so I'll probably fail at the first hurdle. So I'm probably going to take it to my local garage, and I'd like to have a good idea which bits I might need to order in a hurry once they start work.

[CovKid]

I'm not trying to put a dampener on things but its not unusual for the hub carrier to wear slightly oval too, causing play in one plain and not the other. As a minimum I'd definately change the wheel bearings and start afresh. The fact the nut appears loose yet the split pin remain in place could mean wear on the nut, bearing, and faces of the drum so think along those lines.

Its not one of my favourite jobs either and invariably a problem here is quickly transferred to nearby surfaces requiring a proper rebuild. There are enormous loads excerted on hubs, not just in terms of torque settings but on the road too. If you rebuild with knowns rather than unknowns, you should see an end to the problem and peace of mind restored.

Over the years on various T25s I've had occasion to replace the stub axle, more than one hub carrier, several bearings and in once case virtually everything. On hubs I've found the motto "If in doubt, throw it out" not too far off the mark. That also applies to brakes. If I ever have to remove my rear hub, the brake slave cylinder always get replaced if I can't remember when it was last looked at. It comes back to haunt you otherwise. In fact I have a new pair in my cupboard at all times.

Borrow or hire something to handle hub nut and have a go yourself - you'll save a fortune. Its not hard, but check everything carefully as it comes off and replace anything suspect. And by the way, you'll nearly always find a camper owner in your area that has the bar socket and pole needed - just ask around. I loan mine out locally (within 10 mile radius) for a beer or two if one is needed.

[CJH]

Thanks CovKid

Yes, I'm definitely expecting to have to replace various bits. I'd prefer to avoid changing the bearings and then having to do them again because they've been damaged by other worn parts. But I'm new to this job and I don't really know my way around. I found this picture in Bentley:



When the hub nut has been loose there have been definite signs of wear on the rear face of the nut and the surface it tightens against (is that the hub?), so I'd like to replace both the nut and the hub. But which is the part you're referring to as the hub carrier - is it the part labelled 'wheel bearing housing' in the picture above? Any idea where I can get one of those?

I see that I can get a wheel bearing kit with both bearings, both seals and a new split pin. Is it likely that the spacer sleeve(s) should be replaced too? I think I see two of them in the picture above - one near the outer bearing and the 46mm one near the inner bearing.

Good tip regarding the brakes - that's probably the excuse I need to get on top of brake maintenance.

Thanks for the encouragement to have a go myself. When it's being loaded onto a low loader to have the job finished by my local garage I'll send you a photo

[CovKid]

The wheel bearing housing is the hub carrier. You could just try a new hub nut but hard to say without seeing whats gone on. Just bear in mind that a loosened hub nut impacts on everything along that shaft.

[CJH]

Thread revival again. Still haven't done anything about this, apart from assembling some parts and tools (scaffold pole, breaker bar, socket, hub nuts and split pins), but I took the van for an MOT today, and that corner's fine. So I'm wondering, is it possible that the previous owner had recently replaced the bearings but hadn't pressed them into the housing sufficiently? Is that what you have to do in that job? Is it possible that driving on it has pushed the bearing home, causing the hub nut to become loose those two times, and that I don't have anything else to worry about now? Certainly the hub nut hasn't worked loose again since, there doesn't appear to be any bearing noise when driving, and any play in the bearing was acceptable as far as the MOT was concerned.

[kevtherev]

I would continue to "monitor" the situation.

[Jim San]

I'm new to it all to. If you are going to 'continue to monitor the situation' which is what i'd do Get to the nut and mark its location with something like tippex. then just check it periodically for a while to see if there is ANY slight movement - ie try to see if its coming lose before it becomes lose - if thaat makes sense.

or not - just an idea, or just a waste of time

[CJH]

I'm new to it all to. If you are going to 'continue to monitor the situation' which is what i'd do Get to the nut and mark its location with something like tippex. then just check it periodically for a while to see if there is ANY slight movement - ie try to see if its coming lose before it becomes lose - if thaat makes sense.

or not - just an idea, or just a waste of time

Jim - it's a castellated nut with a split pin through it, so I know the nut's not moving.

I would continue to "monitor" the situation.

The advisories on my MOT included 'fluctuating' rear brakes, so I've definitely got some disassembly in that area to come, and I will (eventually) have to check what's really going on. But I was curious whether 'pressing' one of the bearings in was part of the job, and whether it could behave this way if it wasn't pressed fully home.