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MG MGB Technical - Rear hub - wire wheel

Hi again, a new problem!
Decided to get on with fixing the rear brake problem. Have discovered that the hub sounds odd (grinding sound) when I rotate by hand and the hub seems to moves approx half a centimeter if not more before the axle shaft rotates. At first I thought it could be the usual worn diff but the loosness seems to come from the hub end and not the diff end. And the grinding sound comes from the hub end as well - I had removed the drum and brake parts etc. before.
Could it be a very worn bearing?
/Moss
Moss

Remote diagnosis is fraught by definition and your question begs more questions. I suspect you have highlighted two issues; concern over how much 'play' in the drive train is acceptable and perhaps totally disconnected; an audible warning of a problem with the hub.

I suspect your drivetrain has the normal play from the the differential but if you tell us how you measure the free play, someone here will tell you whether you should be worried. 5mm on the outer circumference of the hub is appreciable but probably not serious but is there any other movement ? Laterally for example ?

Turning to the grinding - is it more of a rumble ? - can you by supporting the wheel as you turn it, stop or reduce it ?

I suspect you may have an a wheel bearing prob -

Roger
R Walker

R, you are quite correct - assumptions are always a problem until a solution is found...

The sound is grinding not rumble. And it is coming from the hub end - this I am certain. I can feel it in my hand as I rotate the hub and hear it. With regard to hub movement - holding at 12 and 6 'o' clock there is no vertical movement. Holding at 3 and 9 'o' clock I can feel a slight but definite horisontal movement of the hub.

My method of measurement of the free play when rotating is by looking at one of the bolt holes on the hub and judging how far this moves when the hub rotates before I can feel the free play become a solid movement of the hub and axleshaft together.

It would be nice if it is 'just' the castel nut that needs tightning. Going to clean out all the lithium grease in the hub later today - I have never seen so much very new grease in one place - the other side is different. That is looks like it has just been done concerns me as perhaps the PO has been trying to solve the probpem with grease(No issue from me there -the PO has done alot of other good work. Motor and bodywork - the MOT inspector was surprised how good the underside of the car was (sills etc - very solid) l have owned the car for 18 months and it is the first time I've looked at the rear hubs. The front wheel bearings I changed last summer.
/Moss
Moss

Moss, if it has a lot of grease in there (places other than the wire wheel splines) it sounds like someone has been trying to cover a major problem. There should be no grease at all!
If the hub is moving on the axle you need to get it off to check the inner splines as there should be no movement relative to the axle shaft. 5mm of movement suggests there is very little spline left!
Once the hub is off you can assess the bearing which is held in the axle casing. This is the most likely source of grinding at the outer end.
M McAndrew

I thought along those lines - worn splines and hub bearing - this is the dreaded (for me) bearing which has to be pressed onto the axle shaft by machine, if I have understood correctly. I upload a pic later.
Moss

Is this possible problem with hub/axle shaft splines and bearing the cause of the braking problem on this rear brake or are they independant of each other?

The sypmtom of the brake failure is both when handbrake and/or footbrake applied there is very little response - on the machine at the MOT test the needle on the dial responding to this wheel moved very little, just moving a fraction up the scale whilst on the other side it was good (cannot remember the values).
/Moss
Moss

"the hub seems to moves approx half a centimeter if not more before the axle shaft rotates"

Before the shaft that the hub is connected to i.e. the half-shaft? Or the drive shaft i.e. the prop-shaft from the gearbox? Something very wrong with the former, par for the course with the latter.

The hub should be a tight fit on the half-shaft as there is a tapered seat between the two, this usually has to be knocked or pulled apart when the hub nut has been removed. When that taper is broken there will be a little play in the splines between hub and shaft. It's the 150ft lb on the hub nut that should be stopping movement between hub and shaft when everything in that area is as it should be.

If there is any lateral or vertical movement of the half-shaft relative to the axle casing then the bearing is knackered, and if you can feel/hear crunching or grinding at the hub then it sounds like it has broken up. Even a worn and hence noisy (when running) bearing should not allow the half-shaft to move relative to the half-shaft or axle casing.

Movement, of either hub on half-shaft or half-shaft laterally or vertically to the axle casing should have been very obvious at the wheel, which probably wouldn't have even been upright.
PaulH Solihull

The lack of braking will be down to ... the brakes. Either fluid is not flowing into the slave cylinders because the metal pipe is crushed, or the slave pistons are rusted in the cylinder, or there is oil/grease(!) contamination of the linings and drums, or the hand-brake mechanism is seized. If there is an equal lack of braking for both foot and handbrake then it is likely to be the linings/drums, but could well be one fault with the hydraulics and another with the handbrake mechanism if they haven't been regularly maintained.
PaulH Solihull

I think Paul is right - non working brake = brake problem. Either wear, wrong assembly/adjustment or worn or seized components.

I would open the brakes for inspection on that side, also the other side for a comparative view of things on the 'working' side. I would also be turning the noisy side to see if the sound bothering you was in some way related to the braking 'problem'.
Roger T

Thanks for comments Paul.

The inside of the brake drum and shoes are dry as a bone and not very warn - no sign of brake fluid leaking from the cylinder - although when I moved one of the shoes a small drip of fluid came out of the the side of cylinder where the edge of the shoe sits but this stopped after a few seconds and has not dripped since.
On any account I am going to overhall the hand brake mechanism and by new wheel cylinder. Have looked at your site on rear brakes and mine has been assempled correctly. So it is more than likely the wheel cylinder is siezed and needs replacing and bleeding - cannot seen any crushed pipes.

When I take the wheel sitting on the hub cannot feel any movement either way - but with wheel off and just hub then the vertical movement can be felt at the vertical axis (took hold at 9 and 3 o clock).And the grinding sound and vibration is coming from the hub end.

I have been refering to the half axle end at the hub, not the propshaft into the diff.

But all academic at the moment - have to get the hub off first before going any further. Have to get hold of the 1 5/16 or 33 mm tool to take the castel nut off...

/Moss...on with the weber carb service kit on the kitchen table....'yes dear it won't take too long'....some time in March (I didn't say that out loud!)
Moss

I mean horisontal not vertical...at 9 and 3 o clock when holding.
/Moss
Moss

"When I take the wheel sitting on the hub cannot feel any movement either way - but with wheel off and just hub then the vertical movement can be felt at the vertical axis (took hold at 9 and 3 o clock)."

I really don't see how that can be. Is this play with brake drum off or on? With the wheel on the hub a) you have much more leverage and b) any movement of the hub will be amplified. The only way that can't happen is if somehow tightening the wheel onto the hub is pressing the brake drum onto the backplate. But that would make the wheel very difficult to turn, with a pronounced rubbing noise, which *wouldn't* happen (or not to the same extent) with the wheel off and the hub loosened.

BTW, a tip to undo the hub nut is to put the wheel back on minus its finisher (stud wheels) or spinner (centre-lock) and partially lower the tyre onto the ground. Make sure the car is adequately chocked. But if the hub is loose on the half shaft with the nut tight then there is something very wrong between those two as well, like a missing oil seal cone or the spacer behind it.
PaulH Solihull

I think you are getting much the same advice from all quarters. In your shoes, I would order two new rear brake cylinders, two sheets of fine emery paper, a rear wheel bearing and seal, a cotter pin and rubber boot for the handbrake attachment, and two litres of brake fluid. Then take the hub and brake mechanism to bits - remove the half shaft and inspect.

I don't know how others have got on but I have found it quite easy to slip the new bearing into position so long as the halfshaft is very clean. Just cook the bearing in boiling water but don't burn your fingers!

Held og lykke med det.

Roger

The brake fluid is to re-instate the rear brake and flush the whole system which we all should do every two years. Yes, yes, standfast silicon ..... let's not go down that blind alley
R Walker

Yep, I have come to the same conclusions you all suggest. Have to dismantle it all. Removing the half shaft sounds very daunting... the joys of MG ownership!
R. a fine sentence in Danish...mange tak!!
/Moss
Moss

"Removing the half shaft sounds very daunting"

Not difficult. With the hub removed and the backplate either removed or bent back out of the way on the brake pipe, loosely refit the hub then tap round the back of it with a mallet and it should pull the half-shaft and bearing out of the casing together with the bearing cap which carries the oil seal.

However changing the bearing can be a very different matter, it is a tight interference fit on the half-shaft. Usually a press is required, but some say they have don it by freezing the shaft and heating the bearing in an oven. If Roger got his on just by heating the bearing in water that was very much easier than mine.

Make sure the bearing spacer is fitted between the bearing and the shoulder on the half-shaft, with the flat side facing the bearing.

The tapered oil seal collar goes on last.

It's normal to grease the lip of the oil seal even though it will be running in oil.

There is no gasket between the bearing cap and the axle casing.
PaulH Solihull

Thanks again Paul...my first problem come across is getting the castelled nut off so I can take the hub off.
The spilt pin is in the way - and I cannot fathom how it was got in as the hole in/on the hub does not line up with the the split spin - The top loop which I am supposed to grab and pull is not existent and the ends of mashed and twisted to almost non recognition!
Could the half shaft have moved round? If so this would indicate very very worn internal splines in the hub or end of the axle shaft or both!!

I have tried brute force to rotate the nut and brake the remains of the split pin but the nut will not budge - is it anti-clock wise to tighten on this side and thereby clock wise to loosen (right rear - drivers side if UK side)? This would explain why I cannot budge it - made a 'tool' to stop the hub rotating and am using a long bar so plenty of force being transfered to the nut - the car was starting the lift up - it is secure on axle stands both sides. The wire wheel hubs I have are this way when putting on the spinners.

The axle half shaft removemal sounds easy....it will show!!

/Moss
Moss

this is not going well.... won't be able to answer questions until its off I'm afraid :o(
With a split pin to hold it there in no need for opposite thread, therefore standard anti clockwise to remove and you should be able to snap a pin easily! Sounds like an impact wrench or bigger bar is needed, fingers crossed and hope for the best!

MGmike
M McAndrew

Nope M this is not going well. Have to try again after eating a double perhaps triple portion of weetabix.

At best the problem with grinding is due to the wheel bearing. At second best the halfshaft or hub internal splines are very warn and worst-and really hope it is not this-it's a problem at the diff end.

The other side is fine with no grinding,no undue noise and a smooth rotation of the hub/axle shaft either way when rotating. Something to cheer me up!

..the joys and now woes of MGB ownership

onwards and upwards to the challenge ahead...

/Moss
Moss

Those weetabix really work!!
Got the hub off - used Paul's idea - use the wheel as a counter force - lower the car enough so wheel and thereby hub cannot spin. Hardly any effort to get the nut off. Then took the back plate off...
Now the bearing is exposed. The grinding sound is now a grating, metal on metal, sound coming from the bearng which I can see in front of me when I gently rotate the axle shaft. No sound coming from the diff end - phew!
Oddly diff oil dripped out when I took the bearing cover off - this side of the car is higher than the diff - but this must mean that the oil seal behind the bearing is caput. Not a pleasant smell either - must change it.
Now to remove the axle half shaft.

/Moss
Moss

Moss, good stuff those weetabix. LOL
There's no seal behind the bearing only the one in the bearing cover. The bearing is lubricated by the gear oil and you will get some dripping out of the bearing case.
How were the hub splines?
Now time to assess the damage...

MGmike
M McAndrew

Splines on half-shaft have a mid-grey powder coated look about them - the tops of the splines look flat - when wiped with a rag they look more pointed again but not 'sharp' at the top. Is this how very worn splines look?
Regards the internal splines of the hub hard to tell but with the condition of the half-shaft splines I assume these are also worn....am I looking at half-shaft and wire wheel hub replacement?

What would cause this? I was surprised how easily the hub nut came off with the split pin still in place (despite the weetabix). Could the nut have worked its way loose - the split-pin looked disintergrated before I took the nut off. And the fact the hole for putting in the split-pin did not match up with the pin itself- Very strange...
/Moss
Moss

Please post a picture of the splines before we can comment on the condition?
However, if there is movement between the shaft and hub now it's in bits, a new pair will be required.
It sounds like the nut may have moved slightly and this would cause rapid wear. However, I think the culprit might be the bearing generating heat and causing differential thermal expansion between the shaft and hub.

MGmike
M McAndrew

Splines should be flat-topped. It's wheel/hub splines that wear to a sharp point, hub/half-shaft splines should never wear like that if the nut was tightened to 150 ft lb and all the parts are present and correct. Hardly any effort to get the nut undone is definitely not right. It doesn't take much effort to shear a split-pin with a socket and breaker-bar, however that is very much more force than is on the split-pin in normal use so it should never shear that way, there is nothing (normally) that can turn the nut relative to hub or half-shaft anyway. I also doubt the split-pin had been sheared before, and the nut removed and refitted loosely by a PO, as the ends (loop and legs) would almost certainly have fallen out of the nut. I take it this is wire wheels? It's only those where you have to line up the holes in the hub with the hole in the shaft. Aren't there two holes though? The other one blocked up?

Is the half shaft in or out of the axle casing?

How much slop, both rotational and angular, is there between half-shaft and hub with the hub just slid onto the splines? There will always be some with no nut, but with the oil seal collar and thick outer washer and nut in place the two should be locked together.

If the hub really was loose on the half-shaft, and it had been driven like that, then replacement of both will almost certainly be required. But if you say there was no rocking of the wheel when the wheel was on the hub I can't see that it was loose anyway.

If you do have to replace them remember centre-lock hub half-shafts are shorter than stud hub half-shafts, but centre-lock hubs can be fitted to stud-hub axles, done where someone want to do a cheap conversion to wire wheels.
PaulH Solihull

Pics - says a thousand words - nut and bits of the split pin that were left - the loop was sitting between the castels on the nut.


Moss

Axle half-shaft hub end top view


Moss

Castel nut - the loop was in between the 'castels'. The other bit is the remainder of the split part.


Moss

Inside splines of wire wheel hub end


Moss

Splines on hub


Moss

Usually, a badly worn set of splines will all be leaning in one direction at the top. All of yours seem to be in fairly good condition. RAY
rjm RAY

As Ray says, looks fine. At least the shaft does. Not sure about the hub from the pic. Give everything a good clean and degrease, check the amount of play and there should be little to no movement either laterally or radially between the hub and shaft. If there is movement I would try a different hub first.

best of luck

MGmike
M McAndrew

After looking at my own pics (away form the workshop at a distance)I would have to agree. I think they do not look too worn actually. On the physical evidence so to speak.
Here's aanother from
a different angle where the hub can be seen more clearly.

All this seems to point to a bearing problem. Of course I have not taken out the axle half-shaft yet. But then when the noise and feeling in my hand of grating and grinding is coming from the hub end and when gently rotating no noise comes from the diff end it would seem to confirm my calculated guess. And despite all the comments the split pin did not look or feel right when I took the nut off. Very little is left of it and it was just too easy to get the hub nut off - my intial problem was getting the hub to stop rotating. When that was done no effort at all.

The final test is going to be looking at the splines on the axle half-shaft at the diff end.
/Moss


Moss

The hole didn't line up because it was put together wrong, and the nut was loose because it was not tightened correctly - both are very common. The grey colour is because the DPO did lubricate the splines with antiseize or graphite grease, which is good because it prevented fretting corrosion/wear. Fretting produces red oxide debris together with highly polished contact areas, since iron oxide is in fact jeweler's rouge, a fine abrasive. Wear can be severe if run dry with a loose nut.
Everything looks good; replace the bearing, clean it up, lube all contact areas of tapers, splines, and threads with antiseize, line up the holes, and tighten the nut to 150.

FRM
FR Millmore

I don't like the look of that bearing (sidste billede).
Reckon you are right !
R
R Walker

I think my half-axle arrangemnet is missing something. Have now removed the half-axle. On the drawings for the salisbury tube half-axle there is shown a collar split which seems to be placed behind the castel nut. On mine there is the flat spacer like the one used on the front hubs. This collar split is rounded in height - ie not a flat surface.
The question is should there be this rounded in height collar split or the flat spacer. And is this lack of collar split due steel wheels or wire wheels?
Pic below...
/Moss


Moss

Moss, that's the tapered washer that goes between the castellated nut and hub. The split spacer is behind the hub and provides a running surface for the oil seal (commonly know as collar inner or collar oil seal).
MGmike

M McAndrew

The oil seal collar is shown in your image of 24th Jan. That slides over the half-shaft splines and butts up against the bearing inner race. The parallel face is what the oil seal runs on and is not split, the tapered face is what the hub locates and locks onto and has two splits.

The drive shaft collar that goes under the castellated nut has a single split all the way through. The tapered face again is what the hub locates and locks on to. It's on both stud and centre-lock hubs.

It's a bit difficult to see from your tiny picture just what condition this washer is in, it should look like the attached.

If you are saying your axle didn't have this, then that would explain why the hub was both loose and wobbling!


PaulH Solihull

Paul and M, a silly error on my part, sorry - I have the part. It was covered in grease and dirt and when cleaned up I realised it was the same as in your pic Paul(the small picture uploaded was from a parts shop and I could not recognise it).

Just to clarify things - the tapered end of this split washer faces outwards away from the vehicle or inwards towards the hub? The castelled nut then tightens onto this. On mine the tapered side was inwards towards the hub.

/Moss
Moss

Moss, taper inwards towards the hub with the castellated nut up against the wide side of the washer.

MGmike
M McAndrew

I thought as much. Thanks M.
/Moss
Moss

Update - the half-axle with new bearing and hub now back on, new wheel cylinder, backplate cleaned, rust removed and painted. Now no grating or grinding - smooth rotation.

Now I have to bleed the brakes. I have the late model USA bedix servo - question is can I get away with just bleeding the new wheel cylinder at the rear or do I have to unscrew the piston on the master cylinder to maintain fluid balance in the system the 3,5 turns recommended in the manual?

/Moss
Moss

If you simply gravity bleed the system, you won't have to back off the switch. However, if you use the master cylinder's pressure to bleed the system, you'll have to back off the switch to allow the master cylinder to function properly during the bleeding process. RAY
rjm RAY

Ok,thanks Ray - I'll go for the gravity bleed. Actually I think I have already done it as I screwed the bleed nipple out then in again when I was putting the new wheel cylinder on the backplate - there came a trickle of fliud out for a short time until I had tightened the nipple again...
/Moss
Moss

Air may have got above fluid, so you may still have a bubble. Soon know when you operate the pedal (assuming the brake balance circuit is working).

With the unboosted master the shuttle has to be reset after bleeding, when the rear is bled the warning light would normally be on, so you then have to bleed the front circuit very slowly and carefully, with the ignition on, until the light just goes out. If you go too far and it comes back on again you have to do the same to the rear circuit, and so on.

If you have the boosted master you simply unscrew the switch a few turns, bleed, then screw back.
PaulH Solihull

I have the boosted master. Pedal feels hard but have not turned the ignition yet - minus 9 in my workshop -we had minus 23 three nights ago - and have to adjust my 'serviced' weber carb !! My goodness I'm slow and very cold...!
Moss

Boosted master does give a heavy pedal without the engine running, you may find it sinks a bit with the engine running.
PaulH Solihull

Trying to warm up the workshop so I can test the system later on this evening....have bought a one man bleed kit now, so going to bleed the system - might as well while I'm at it. I've never done it before and do not know about the PO so now a good time as any. Bit apprehensive about the 3.5 turns to sink the piston in the master cylinder - what happens if it comes out-brake fluid everywhere...

One thing I did notice when I was screwing the bleed nipple back in was that fluid came out from around the nipple (until it was tight, of course) and not through the hole for bleeding - is this normal?

/Moss

Moss

It's more common when the bleed nipple has foreign matter in it, but if fluid stops coming out when the bleed nipple is fully tightened, then everything is normal. RAY
rjm RAY

Bleed nipples are generally not tight in their threads, so some fluid may leak past them. When tightened the solid tip of the nipple seals the cylinder so no more fluid can reach the threads anyway.
PaulH Solihull

This thread was discussed between 20/01/2012 and 08/02/2012

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