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MG Midget and Sprite Technical - F/Wheel bearing RENOVATION. Update

Here it is folks, just what you've all been waiting for. ;-).

Now you'll all remember, that a little while ago, I renovated an old set of my front wheel bearings. re-face adjusted them, you might say, if you like. Or you might not of course. Anyway, after the said deed, whereas prior to grinding them a little, I had wheel bearing play with these bearings, post this engineering marvel, I didn't. So having the now 'renovated' outer front wheel bearing back in pride of place, I went for a drive, and have been driving on the same renovated bearing ever since.

Now I was going to wait for 6 months to pass --- it's only been a little over 4, (06 July 2012)--- , however, knowing that you were all eagerly anticipating some news, and that several shops are selling xmas cards and decorations, I decided to update you all now. :).

And the news is, I still have no wheel bearing play, the wheel still spins freely and quietly, and all in all, I reckon it's worked. Yes yes I hear you ask, how many miles is that? Well in truth, not too many, but enough. Quite how many I can't say, because I forgot to note the milage. However, I did the deed, only a week after getting an MOT, but until I look up the information on the MOT website, I can't find the mileage. Bloody new test cert, doesn't have it.

What follows is the original post where I describe how I renovated the bearing. --- For those of you who might have forgotten. lol.

Posted 06 July 2012 at 20:35:20 UK time
Keep your old original RHP bearings and recondition them.

Working out how much play there is in the bearing, for a given amount of play at the rim at the tyre, was discussed a few posts back. So I've been experimenting.

I knew (because I keep so much "junk") I must have an old set of "worn out", RHP front wheel bearings somewhere that I changed years ago, and never threw out. So I went through all the stuff in old boxes in my loft and garage, and found 1 old set of RHP inner and outer front wheel bearings. I can't remember when I changed them, but it must have been at least 12 or 13 years ago. There should be another old set somewhere. The joys of being a hoarder.

Anyway, I installed the old set of supposedly worn out RHPs I found into a spare hub. I took off one of the hubs currently on the Sprite, and bolted the spare hub with the old worn RHPs onto to the spindle. I measured the movement at the tyre rim where I could best see it (approximately 279mm out from the centre of the spindle), and it was about 2mm. I was surprised it was so little, because it feels like much more when you rock the wheel. And yes I did ensure it was the hub rocking, and NOT play in other parts such fulcrums and king pin/bushes.

A bit of basic trig on right angled triangles, and the movement at the ball centres of the outer bearing, calculates at 0.119856631mm. Or about 4thou". So I divided that in half as the bearing is pivoting, thus 2thou" wear play in the bearings. I don't know how much that's divided between the outer and the inner bearings, but I do know from long past experience, that it's the outer bearing that wears more than the inner bearing.

FORGET LOOKING FOR NOS RHP'S or worrying about buying modern cheaper alternatives, that may or may not fit properly. Look out your OOS. Old, old stock. Aka, worn bearings. Because you can re-face them. I just did, and there is no longer any play in the old RHP bearings that I put in the spare hub. The 2mm movement I described earlier is completely gone, and the hub spins freely and smoothly.

I re-faced the inner (thrust side) face, of the inner race of the outer bearing. I did it by grinding it along some 280 grit wet/dry paper on the flat surface of an unused India oil stone. I did it over about 30 minutes in 3 intervals, trial fitting the bearing back into the hub and the hub on the spindle each time. Using a vernier calliper and feeler gauge, if feels like I ground off a little over 1thou", but it could be a little more or less.

Either way, I've transferred my disc to the hub and I'm going to keep these bearings on the car for the next six months and see how it goes. But I reckon they are fine- revived. All I've done is compensate for the internal wear in the raceway, by bringing the faces back closer to the original tolerance.

You could achieve the same thing by adding a shim behind the outer race, or reducing the length of the spindle spacer just as some people have done with the cheaper "non-face adjusted" moderns to make them fit. Personally I don't want to alter the spacer, and it was easier to grind the inner race than keep removing the outer race and trialling shims.

Of course you could buy a set of Moss or sussex or any of the other 7000 series and shim those, but the advantage of this is that 1) you already own a set of RHPs, 2) they have the correct 2mm radius, 3) they won't be too tight, as you already know how much play there is in them.

Why hasn't anybody done this before? Has anybody? I'd be surprised if I'm the first.

Anyway, it works. Objections please, keeping in mind that it works. :)

Here's a picture of the inner race, sitting on the wet/dry paper on the India oil stone.







Lawrence Slater

This is a ball bearing? You are taking up wear by displacing the race sideways?
Art Pearse

Congratz... Job well done, sometimes you just have to muscel down and make something like this work in your favor regardless what others say

But no, I wont be following your lead on this, im going with the 40 degree angular contact bearings... As i already own them.

But im glad you found a way to make the orginals work, thats a true accomishment

Prop
Prop and the Blackhole Midget

How do you get the bearing out in one piece????
Onno K

From the photo above (or below, if you're Lawrence) you can see that the bearing separated.
Dave O'Neill2

Onno,
I had removed these old RHP bearings ages ago, because they were worn (wheel play/wobble). I then decided as described below, to see if it was possible to remove the internal play.

BTW, I only 'adjusted' the outer bearing, because my past experience has led me to believe that the outer wears more than the inner.

So I drifted them both (inner and outer) into a spare hub, and deliberately pushed on the inner race of the outer bearing (the smaller of the two) to pop the bearing apart. I did this when the bearing was in the hub, because I feared possibily cracking the outer race if it wasn't contained in the hub.

Once apart, I ground the face in stages as described below.

After that I popped it back in and fitted to the car.

Art,
if I understand you correctly, yes I suppose I am. Imagine you buy the new cheap moderns, that some people have had to shim, or grind metal off the spacer to make fit properly. Well instead of grinding metal off the spacer, I ground it off the inner face of the inner race of the outer bearing. Thus reducing the internal clearance in the outer bearing, back to nearer or the same as it would have been when new.

The plain fact is, that it has worked. How long for, I won't know until they fail. Frankly even I expected they would fail after a few hundred miles. However, they haven't after at least 2000 miles. So instead of leaving them in for just 6 months, I'm going to leave them in indefinitely.

My argument is this.

If you have original RHP bearings in your hubs, and you start to get wheel play due to the bearings, then if you don't mind a bit of your own time and effort, you might just as well spend it renovating your original RHPs, as shimming or spacing new moderns, if they don't fit properly.

The obvious benefits are: They are free since you already own them, and they are the correct spec, becaue they're RHP originals.

Now if you can get NOS RHP very cheaply, or the suppliers start providing CHEAP moderns that fit properly, or cheap bearings to the same spec as RHP (and it seems that at least one is, "Bull Motive"), or you don't mind spending circa 100 quid per side for SKF or equivalent, then this is a complete waste of time.

Me? I just like to fix things, and if I can extend the life of something with very little effort, I enjoy doing it.
Lawrence Slater

Sorry, just to clarify that Onno.

Originally, when I took these old RHP bearings out of the hub, I almost certainly popped the inner race of the outer bearing. My hubs have always slid off the axle complete without the inner separating, and it's much easier to pop the outer than the inner. Then after removing the spacer, I used the drift pockets to remove the rest of the outer, and removed the inner bearing as a complete bearing. It's a long time ago, but once out the hubs, I probably just popped the outer bearing back together again.

It didn't crack the outer race, but I have cracked the outer race in the past. So when decided to try this renovation, I installed the bearings into a hub again to counter the stress of popping the inner race. Pushing the inner race out of the outer leaves small indents in the extreme rim of the outer race, but hasn't damaged the balls or the raceway.

This is evidenced by the fact, that the bearings on the car, and after at least 2000 miles, still spin freely and quietly and have no detectable play.

Lawrence Slater

Onno: The front bearings are angular contact bearings and if they come apart, as they will do when the hub is stripped down, the recommendation is that they should be replaced. This style of bearing is different to conventional deep groove ball bearings as you have in the back axle. They are designed to run under preload and the alignment of the vertical faces is carefuly preset on manufacture to be a certain figure under that preload. The previous thread on this topic had better explanations than mine!

Ok, that's in the perfect world and what Lawrence is doing is ignoring the "prefect world" and applying practicality and may (or may not) get away with it. Points for recycling! Just remember to stop and pick up the wheel out of the hedge.

But there is one issue that does worry me and Lawrence has avoided. What torque are you using on the clamping nut :-)) ?
Graeme W

Hi Graeme,
They only come apart IF the inner race of the inner bearing, is a very tight fit on the spindle. It's not supposed to be, and on mine and many others it isn't, and the hub comes off cleanly with the bearings complete.

As you know, because the internal spacer obscures the drift poskets, the only way to remove the bearings from the hub, is to 'pop' one of the inner raceways. This is VERY easy, and requires less pressure if doing it to the outer bearing. Once one is out the spacer can be removed and the other complete bearing drifted out.

It's recommended that if separated they should be replaced. However, in practice, many people have found that you can pop them back together again and the bearing hasn't suffered at all. Pushing the inner out of the outer results in very small dents in the extreme lip of the outer race, but only in a couple of places, as the bearings 'pops' at an angle. Not visible to the naked eye, or under a 6 times magnifer . Under a microscope, I've no doubt the balls might show some marks too). In practice though, I've done this countless times and used the bearings for 10's of thousands of miles afterwards.

So the perfect and practical world aren't actually so far apart it seems. I and others have been getting away with this for years. Until now though, I've never tried to renovate them once there was play.

I wasn't avoiding the queation of torque. In the other long thread, where I first mentioned that I had done this, I'm sure I said I torqued up as normal.

For clarity, I applied the same torque as given in the book. 46lbs, but actually 50, as my wrench isn't that well marked.

Lawrence Slater

Lawrence - the torque question was tongue in cheek! The manual I think is quite clear on this one.

The main element of my post was to clarify that these are not "normal" bearings in s&M terms as they are angualar contact ball bearings. That's what the complex earlier post was about because of the way these bearings should ideally be specified.

The difficulty with our cars is that they will never be perfect unless you are prepared to dig very deeply into pockets. Even then, I'm not convinced that replacing every dubious parts with new doesn't bring its own problems as a considerable percentage of new parts fail prematurely because of dubious quality or specs. There has to be a element that accepts some wear and free play as long as it's not dangerous or going to lead to breakdown on the road. It's called "keeping them going" in my book. Adapting bearings which are not to spec because the correct ones are unavailable, or refurbishing old to recyle is part of the game. The value of this BBS is to help decide what can or can't be done.

Off to start the reart axle. I dread to think what posts that is going to generate.
Graeme W

I completely agree with you Graeme. I've been keeping mine going for years, by some very dubious means.

But I don't agree that it costs that much, although my perception of perfect with respect to a Spridget, might not be the same as other peoples, and very probably isn't. That said though, these cars were pretty far from perfect when they fell of the production line, and that's half the fun of them. :)

I wouldn't have even considered re-using these bearings in the past, because the original RHPs were not only freely available, but were extremely cheap, especially when you think how long they last. But with all the talk of poor fitting cheap moderns, I got to wondering, so I had a go.

It's a bit of fun, that as it happens, seems to be working rather well, so that can't be at all bad. :)
Lawrence Slater

Error posting.
Lawrence Slater

"IF the inner race of the inner bearing, is a very tight fit on the spindle. It's not supposed to be..."

Why is the inner race here deemed to be a "loose fit" and yet needs to be a drive fit for the rear axle? Ok, dfferent style of bearing but the load dynamics are the same for both. Both are clamped between a nut and a shoulder!
Graeme W

Has anyone ever had to press/drift a front hub onto the stub-axle?

I certainly haven't.

I've never had the inner bearing stick onto a stub-axle either.
Dave O'Neill2

Lawrence, I see its an angular contact bearing, so your adjustment is kosher. On my MGA, the standard issue BB was too loose a clearance, so I had to order a tighter clearance, I think C1 to make it acceptable.
Art Pearse

If you can remove the hub while the inner bearing stays on the stub axle your hub it worn!
This increases the wear rate of frontwheelbearings a lot.

It is IMHO the most un diagnosed problems leading to short wheelbearing life.
And one of the reasons new bearings have a sh*tty reputation.

The bearings should slide on and off the stubaxle without trouble.
A lot of recon stubs have been sandblasted making it harder to slide the bearings on and off.

And IMO if you want a bearing you can adjust and split without problems go for tapers.

I am in the proces of comparing ball vs taper bearings.
The left front is on new ballbearings and the right is on tapers.
Let's see what the MOT guy has to say in a month
Onno K

I agree with you Onno. But I think most people --- who have the problem that is -- experience the inner bearing separating from the outer, not coming out of the hub complete, and that might also be because the moderns they've fitted have an inner radius that's too small, causing the inner race to jam on the stub axle fillet when torqued up.

Also, you slightly missed my point about doing this renovation on my old bearings. My experiment was as a result of the loooooonnnnnng thread about replacement moderns. All that discussion about angular contact bearings, made me realise that you could take up play in your old 'worn out' original RHP bearings, instead of having to buy and shim ill fiting new cheap moderns, or pay a small fortune for moderns that fit correctly. So I'll say it again, you already own the bearings -- so they're free, you know in advance how much play is in them, and you know the inner radius is correct for the stub axle. All it then takes is a little time. Now suppose these last another 40/50 thousand miles. I personally reckon that's better than adapting to tapers.

Of course, if Bull Motive fit correctly, and it's now been confirmed they do, and if Moss et al continue/start to stock new bearings that fit correctly, at a cheap price, then my solution is a complete waste of time, however interesting or satisfying it was to do it. But then, so too would be converting to tapers, and tapers are more expensive to convert to, than it would be to buy cheap angular contacts that fit correctly.

Art, thanks for confirming my view that this works because they are angular.

Yup Graeme, exactly. Torqued to only 46lbs, both bearings are a slide fit on the front stub axle, and nobody has ever been concerned about inner bearing race rotation.

Lawrence Slater

This thread was discussed between 12/10/2012 and 15/10/2012

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