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MG Midget and Sprite Technical - Removing bearings from front hubs

Does anyone know a way to remove the wheel bearings from front hubs without damaging the bearings so that they can be re-used ?

I have some good face adusted ones in the wrong hubs, and at about £100 a side I would like to remove them for fitting into some alloy hubs that I have had for a while.

Any ideas ? ......Turbo Bob will be along soon.

Ian
Ian Webb '73 GAN5

Ian,

An interesting question. In order to remove the bearings without damage you have to be able to press or knock out the outer races from the hub and that requires being able to get at the drift grooves. I'm not sure that the spacer can be moved to one side enough to allow a punch in to do that and the hub I have on the bench I'm not going to visit at this time of the evening to find out. If it can be moved enough then there is an opportunity.

Another thought is differential expansion or contraction in this case. I assume the hub is some form of iron possibly cast or malleable and so its expansion coefficient is lower than steel so if you can cool the assembly enough the bearings may shrink enough more than the hub to allow the bearings to drop out or be pushed out with a load low enough not to damage them. Got any liquid nitrogen or other cold stuff handy?
David Billington

as long as they are off the spindles and stayed in the hubs then yes you can drift them out using the grooves provided; remove oil seal, clean away as much grease as possible, do the inner one, remove spacer, then do the outer.
David Smith

Bit of a naive question this, but what damage is actually done to the bearing if the inner and outer races do separate? I have simply cleaned the balls and cage up and reassembled with fresh grease. It was some while ago but I don't recall there being any obvious damage and the wheel hasn't fallen off yet! Are the newer replacement bearings different?
Guy

Gents
Its as DB says the spacer cannot be moved to one side enough to give acess to the pockets that are provided for normal method drifting out purposes. IIRC one normally knocks out the rear/inner centre race first and that allows the spacer to be removed easily.

From what DB says about the the steel bearings shrinking more than the cast iron hub I will try the chilling method,as I do have access to liguid nitrogen. Its worth a try as I have nothing to loose.

Guy, whilst I agree with what your saying up to a point, as I have done it myself in the past, when the bearing races separate either the balls or the races will be damaged its just usually not visible to the naked eye. When the manufacturer assembles the bearings I assume he heats the outer race and chills the balls to permit assembly without damage, unless somebody can tell me differently .....which makes me think that I might know some guys who used to work for Timken when they still assembled bearings in the UK .....I will have to make some enguires.

The hubs/stub axle & kingpin are all clean and on the bench, they arn't part of a running car, just another little upgrade project I'm working on.

Ian
Ian Webb '73 GAN5

My view (FWIW) on alloy hubs is that they are grief... I have yet to know a race car that has run them that hasn't broken one at some point...

I know that suspension loadings etc are less on road cars, but then the service interval is much greater...

I'd be inclined to stick with your original steel hubs...
James Bilsland

HI Ian don't have an immediate answer as I have never tried to do this but understand everything that has been said so far. Will get back to you later if I may when I have checked up on something.
For info
Bearing that will not simply fall apart such as normal ball races are put together by puting all the balls to one side then preading them around the bearing and keeping them position when the cage is installed.
Bob Turbo Midget England

James
I have heard before about the failures some have had, but nobody has told me exactly where they fail, do you know where they fail and maybe put me on to someone who has an example ? The rumour I heard was of a very sharp radius in one area, but I dont know where, if I can find out I can keep an eye on it.

There is no good reason for alloy hubs to fail per-se, its just that they need to have the design detail correct. I havn't used them on a midget before, but I have been involved with them on some Ford rally cars where its quite common, and they have been around for years......and can be bought for a reasonable price !!

Ian

Ian Webb '73 GAN5

Hi Ian

Truthfully I don't know exactly where they fail as I've always steered well clear - I know of at least 4 occasions when one has failed on a race car - the last I can recall was Mark Turner at Brands some years back causing a relatively big 'off'. The ones that have failed always seem to do so catastrophically so I'm not sure that an inspection regime will help.

I know they run alloy hubs on Escorts but the hub and bearing shapes and sizes are different - It may be that your hubs are fine and will cause you no problems - personally I would not bother because they don't give that much unsprung weight advantage for the potential unreliability and safety implications involved...

Cheers

JB
James Bilsland

OK Ian I have some information for you (and anyone else interested )

I have told it wrong about how these bearings are assembled, they are assembled as follows.

The outer races are placed on a hot plate that is set at 120 degrees.

The inner race complete with balls and cage are at ambient temperature (20) and are simply dropped into the hot outer race.

This ofcourse means that the 100 degree temp difference is enough to split the bearing.

My friend from NSK also suggested that the cast iron hub ought to expand faster/more than the bearing outer race and if the whole unit were placed into an oven set to 120 degrees then there is a good chance the whole bearing would almost fall out. The bearing will not be damaged in temperatures upto 135 degrees.

Alternatively if you heat up the hub assembly and cooled the inner race with Nitrogen the it ought to fall out.

What bearings are they Ian ? are they the NSK 40degree angular contact or the NOS from other sources?

Hope this helps.
Robert (Bob) Midget Turbo

Robert (Bob)

Interesting what your mate has to say about the heating of the hubs causing the bearings to drop out. I was aware of the different materials but am not sure about what the hub material actually is. The bearing material should be a carbon chromium steel as has been used for bearings for ages but the hub material is more uncertain, I assumed a malleable iron but can be corrected. One would have to research or test the expansion of the hub material to be more sure. Late last night I did a quick search and turned up the likes of

http://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html

and
http://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html

which seemed to point at the bearing COE being greater than the hub so cooling the assembly should release the bearing but we won't know for sure until it has been tried.

IIRC malleable iron is white cast iron that has been annealed to allow the graphite in the iron to form into spheroids and transforms the materials from being brittle to malleable.
David Billington

Not sure if this thought is of any help, but the plumbing trade sell cannisters of freezing agent for temporarily isolating pipework. Would this provide sufficient cooling?

http://tinyurl.com/75z33ma
Guy

Robert, I don't understand what you are saying about the bearing assembly. For 100 C difference in temperature of the outer race vs the ball assembly, means only about a few thousandths of an inch. What stops the balls falling out is the depth of the grooves in the races, which must surely be >>> a few thou. If the grooves are that shallow the bearing would not take any side load.
Art Pearse

Art,

We are talking about angular contact bearings and so in one direction they can take substantial thrust load as seen in the wheel bearing assembly but in the opposing direction they can be sprung apart very easily as they're not intended to take load in that direction.
David Billington

OK, I thought they were ordinary BB, like on the MGA.
Art Pearse

Gents
Thanks for the helpfull comments, although not conclusive... so it looks like I will have to try both methods, which I should be able to do, maybe next week.

Bob; the two standard hubs I am working with have R&M 3MJT17 & 34LJT25 bearings, which are the original face adjusted type I think ? They seem to be in useable condition, but i dont remember where they cam fromm ! For me the point is that if I can extract them from the old hub and re use them ok,it will save almost enough beer tokens from my limited budget to buy some alloy brake calipers ....which are also part of the experiment, they would be metro type calipers.

James; it was Mark Turner who mentioned to me about the sharp radius on some hubs, but I failed to get details from him at the time.

Ian
Ian Webb '73 GAN5

Yes Art as David explained these are angular contact and not Ball races.

In fact the first explanation I gave on assembly was indeed for a normal ball bearing and not the Angular contact that I was thankfully able to correct.

In fairness to NSK I suppose I prompted the idea of heating the full assembly in the hope that the hub would expand more than the outer race, My mate thought it could well do but in fairness he was not positive about that but could be worth a try. I suspect heating the unit in an oven and cooling the inner race would allow one of the bearings to be split allowing I hope easy access to the other.

Guy taking your point about hitting it and catching everything and reassembling, whilst this is possible damage could very easily occur so is not to be advised for bearings hat are to be reused.

Hope Ian lets us know the results.
Robert (Bob) Midget Turbo

Bob
I had a go at removing the R&M bearings from two hubs last night; I think I can say chilling the hubs was a success.

I would not say the bearings fell out of the hubs but I was able to drift the 3 of the 4 four bearings out fairly easily and the fourth I had to be a little firmer with but it drifted out with out damage. One of the front bearing split itself with just a light tap and the other front bearing drifted out complete, (bearing in mind that the first operation is to hit the centre race as you cannot get to the small pockets until the spacer is removed, after that it is all normal method)

In conclusion I am happy that I have ended with 2 pairs of reuseable face adjusted bearings ....one of each type of the original R&M bearings.

Also I was then able to directly compare the weight of a bare cast iron hub against my bare alloy hub which I couldnt do before; the CI hub is 1.9 kg and the alloy hub is 840grm

Ian
Ian Webb '73 GAN5

The only time I have had the bearings come apart, is when drawing the hub off the stub axle. I have never had any difficulties at all with removing the bearings from the hub. Perhaps I am misunderstanding the whole issue?

When drawing the hub off, sometimes the inner race of the inner bearing remains fast on the stub axle so that the bearing then comes apart. That then leaves the problem of getting the inner race off (without a professional knife-edged puller). If the bearing is a reject anyway the quick solution is to cut part way through with an angle grinder and split it with a cold chisel. Care needed not to mark the axle! I have also got the inner race off by starting with a knife blade, then levering with chisel and screwdriver until I could get a puller on. I have then reassembled the bearing with fresh grease and re-used without any problems. It is fiddly holding all the parts together and getting the balls in place again, but there seems to be a combination of parts and angles that allows the thing to go back together with a bit of thumb pressure and a "click".
Guy

Guy
You have got hold of the wrong end of the stick......I am trying to remove some servicable bearings from one pair of hubs that are not fitted to a car.....for refitting into a different type of hub. I am trying to avoid using any force so that the servicable bearings are not damaged. The correct type of bearings cost something like £100 per side .....I dont have that money lying around for this little experiment, hence the need to reuse.
Ian
Ian Webb '73 GAN5

Ah, right. Sorry!
I had seen discussion before about having to replace these expensive bearings because of damage when removing. But I have never had any difficulty once the hub was off the car - so long as the inner race draws off intact with the outer.
Guy

Guy
IMO the outer race of bearing really shouldnt pull out that easily, because when assembled at the factory they would have heated the cast iron hub and pressed in cooler and therefore smaller bearing, so ensuring a very tight fit....at least I assume they would assemble it that way as its the commmon engineering method, but I am to be told otherwise.
Ian
Ian Webb '73 GAN5

Ian
<<because when assembled at the factory they would have heated the cast iron hub and pressed in cooler and therefore smaller bearing, so ensuring a very tight fit....at least I assume they would assemble it that way>>
can't believe you said that, you know what's said about 'assume' !
it sounds highly unlikely to me, we don't fit replacements that way, garages don't fit replacements that way, so why should the factory?
David Smith

Ian,

Did you chill the hubs in liquid nitrogen in the end and do you know how cold the hubs actually got. A good result anyway.
David Billington

Ian

I'm still not convinced its worth the risk for 1000g approx per side - you'd probably win close to that unsprung weight saving by changing to alloy calipers...

Let us know how you get on with the alloy hubs

JB
James B

Gents

David S:-are you saying that because most people would fit hub bearings with a hammer and a socket the factory must have done that too !!!! ....... I would hope they might have used the best method. ie heating the hub and fitting the bearing without undue force.......but then maybe not as it might have cost a farthing more !!

David B:- Yes I chilled with liquid nitrogen but I didnt measure the temp as a thermometer wasnt handy. They were well chilled having stood in LN for 15 minutes and covered in thick frost.

James:- I am going for alloy calipers (Metro type) as well, as part of the same exercise, I dont have the numbers handy on those, but IIRC its about another 1.5kgs saving per side. I am also removing vented discs from the car and reverting to thin disc to save even more weight. The exercise is to build the lightest front suspension possible.

Ian
Ian Webb '73 GAN5

Ian
<I would hope they might have used the best method. ie heating the hub >
now I'm confused, is it heating the hub or chilling the hub?
Certainly on my occasional visits to Abingdon in the late 70s I don't remember seeing any liquid nitrogen tanks around the place.
As far back as the early 60s the official workshop manual refers to 'drifting the bearings in with tool 18G134 and adaptors' and this would have sufficed in the factory too, although they may have used a special press to do several at once to cope with the volumes. I'll also suggest they would have been done individually by hand in the ST shop for the comps builds.
David Smith

David Smith,

Heating the hub is to aid putting the bearings into place as the hub will expand allowing easier fitting of the cooler bearing. Chilling the hub was suggested for removing installed bearings as it seemed that the hub material has a lower coefficient of expansion (COE) than the bearings and so when sufficiently cooled the bearing would contract more than the hub allowing the bearing to be removed more easily and hopefully without damage. Ian has tried the chilling, as he has access to liquid nitrogen, and has reported success. See http://en.wikipedia.org/wiki/Liquid_nitrogen , -210C I expect Ian has good gloves and it's no wonder the hubs were frosty.
David Billington

David S,
I always thought the Official workshop manual to which you refer was published by the factory not for their own assembly lines but for for MG/Leyland Dealerships .....not the FACTORY. I have never said that the method to which you refer is wrong, what I meant on both ocassions was the FACTORY, where they would be assembling hundreds of hubs; heating the hubs for easy assembly there would be quicker IMO. Bob mentioned that was the exactly the way the bearings themselves were assembled at the R&M bearing FACTORY, so I am not suggesting they might have used that method without an example being available.

I cannot see where I said the factory were chilling the hubs ...why are you confused ?

David B explains it far more eloquently than I, so I wont repeat the explanation.

Ian

Ian Webb '73 GAN5

Never mind all that at least you have got your expensive bearings out mate so that can only be a good thing.

I was hoping to gain a second or 2 on you this year Ian but your like the Red Bull team and are moving ahead again. :)

Mind I can argue I have got too old!! LOL.
Robert (Bob) Midget Turbo

Ian

Do you have any alloy Metro calipers yet? We have a spare pair here, bought for the turbo car project but won't fit the 240mm discs we are using that well so are moving on to something else. They were GBP205, we have some returns going back this week we could slip them in with if you are interested. Email at paulatmgpartsdotcodotnz.
Paul Walbran

Paul
No I dont have the alloy calipers yet, I was looking to buy some just this week,I was plannng to buy from Minisport but I want non vented Metro type and they are not very common, plenty of the vented disc alloy calipers available and at sensible prices, so at the moment i am scratching my head a bit !

HiSpec do have a suitable caliper but it doesnt take Metro type pads which I would prefer to stick with.

What type are yours ? I might well be interested, as an option is to buy a vented caliper and mill it down to narrow it for non vented....the tricky part will be o ring groove but I can probably get that done ok.

Ian

Ian Webb '73 GAN5

Ian

These were the other way round - non vented and I needed them for vented and had to get a spacer kit in addition. To clarify, they were for a Mini and the 202GBP was for the pair, current retail incl VAT 300.
Paul Walbran

Just went to check the pads - they are Metro.
The calipers were from Minispares.
Paul Walbran

Paul
Yes I would be interested in those, I assume they could be changed back to non vented by removing the spacer ?

Are they the red Paddy Hopkirk type ? ......that Miniport also offered me.

Please email me the price you want at : ian dot webb57@hotmail dot com

Ian
Ian Webb '73 GAN5

Ian , I cant wait to see what the rest of your work leads to. Have you weighed your car in full trim? Mine is qutie heavy 770kg. this was with 3/4 tank of fuel and spare etc, everything that is in it, when we go to a start line for a Lanes Rally. The dream goal would be 700kg but I am not sure if its possible for what i use the car for. I made note of your email so will send you a few pictures in regards to the exhaust.

Will
WDT Corry

Paul
You have email.

Will
I'm just tinkering really trying to minimise understeer and improve low speed turn in, by all means that dont cost to much !

Also working on a slipper joint mount for the rear spring, so that I can go to a 5 link rear end, I have 3 links already so its fairly easy.

When I get the chassis working better I will bolt on some better rubber...but not until then, as I feel thats ultimately the better way.
Ian
Ian Webb '73 GAN5

This thread was discussed between 10/01/2012 and 22/01/2012

MG Midget and Sprite Technical index

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