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MG Midget and Sprite Technical - Front discs and bearings

Chaps

At the very great risk of igniting fearsome debate, and never having changed the discs/bearings on a midget, I would care to confirm a few things.

Nearside pads rattle about on corners and the wiggle test on the wheel seems to indicate bearings may be on their way out. I have also had a pair of new standard discs lying about for some time, so a good opportunity to fit them at last perhaps.

Therefore

Am I correct in thinking that once the castellated nut is removed, then hub, disc and bearings can be removedving l from the stub axle as a single entity? I take the point that that the inner bearing may pop....

Incidentally, I have no puller - having loaned it to a mate years ago and it not returning. Alternative methods of removing the assembly welcome....if it is stubborn of course.

Does the disc just slip over the hub held to it with the 4 bolts, and with the bearings in turn sitting inside the hub?

Best method of removing the inner bearing - without destroying it.

Best place to buy the correctly machined bearings...MGOC appears to have something for a reasonable price.

My thanks as always

Mark




Mark O

Hi

Yes the hub disc and bearings all come off when you remove the castellated nut. (you have to remove the caliper too of course). Usually(!)the hub comes off the stub axle with a good yank on the disc. If not I have found putting the wheel back on and pulling on that can help.

If your going to renew the bearings then it doesn't matter if the inner bearing is damaged or have I missed something? I just knock it out of the hub with a brass drift. The tricky problem is if the inner track is left on the stub axle as it can be difficult to shift. There was a proper BMC tool for removing it but I resorted to gentle persuasion with a small sharp cold chisel tapping gently on the inner race until it moved enough so I could lever it off.

The disc as you say is held by the 4 set bolts to the hub.

The bearings are now being remanufactured to the correct tolerances and are about £40 per corner I believe. Don't be tempted by cheap ones as the tolerances can be wrong!!

Bob
Bob Beaumont

same here mark. think i need to change one for the first time as well. will also be interested in info.
bob.
bob taylor

Hi Mark,
Before you start I would suggest that you have a very careful inspection of the suspension. Despite all of the conversations there have been about wheel bearings, they are pretty robust on these cars. The bottom trunnion and the king pin bushes are far more likely to create "a rattle on corners" than the pads. In fact I am not sure that the pads would ever audibly rattle.

Best way to check those components for wear, is actually by feel. Jack the car up, reach behind the wheel with one arm and put your finger across the joint to be tested. e.g so touching the king pin and the lower suspension A frame; between the hub carrier and the lower knuckle of the king pin and between the hub carrier and the top trunnion housing. Then do the waggle test - it can be done on your own but is easier if someone else to apply the waggle forces.

I know this isn't actually what you were asking about, but 10 minutes to assess wear there would be time well spent. Movement at the wheel rim isn't necessarily the wheel bearings. Have you tested for movement with the brakes applied as well as brakes free? Have you checked for track rod end movement or for slack in the steering rack itself?

Once you do come to removing the hub a puller is best if the bearings have got a good hold, but without one try removing the wheel and castellated hub nut, then replacing the wheel the wrong way around (outer face against the hub). Just start a couple of wheel nuts on their threads, slip a spacer bar of some sort - suitable spanner will do, across between the loose wheel and the axle pin and then whilst juggling all the lose bits, tighten the wheel nuts evenly. It should pull the hub forwards and off, or at least enough to get it started free. Sometimes it helps to slacken the castellated nut off a few turns, but leave it on the axle for the bar to press against and to protect the thread.
Guy W

Chaps

Once again you rise to the occasion. Many thanks. Love your improvised puller Guy, and many thanks for the useful guide.

Bob - I considered re-using the bearings if the issue was elsewhere - as Guy suggests.

Bob/anyone..Are MGOC's stub axle bearing kit for about 40 quid - item 63 on schematic - correctly manufactured.
Mark O

hi mark,
i haven't got a clue about who has right bearings mate. waiting for someone to come along and confirm. I'm sure they will later. waiting for the rain to stop at the moment its piddling down. want to check movement with brake on.
bob.
bob taylor

Why not go direct to Chris Buckenham for bearings, heritagecarparts.com. If you want to go to MGOC I'm pretty sure Chris said on here that he was now supplying them with his which are the correct spec.

Trev
Trevor Mason

bear in mind that MGOC, like many larger retailers, may have dual sourcing in place, so no guarantee where the ones you actually get come from.
David Smith

There was a 'news' item in the MGOC mag a few months back, saying that they are now selling correctly spec'd bearings!

Which presumably means that they were previously selling sh*te!
Dave O'Neill 2

If all else fails I have got some original NOS R&M bearing kits.

Bob
Bob Beaumont

Bl**dy 'ell Bob - no wonder there is a world shortage of original NOS bearings! How many sets have you acquired over the years?

If you have wire wheels (I see Mark doesn't) you can use a spacer on the end of the stub axle after removing the nut. Then replace the wheel nut (no wheel) and if the spacer is the right length you can ease the assembly off as you tighten the wheel nut.

If the disk is out of line relative to the callipers after assembly you may well have fitted a bearing without the correct radius on the inner race so it doesn't go completely "home".


Graeme Williams

I thought someone said Lawrence bought them all? ;-)
David Smith

No, only one particular set, but that's history now.
Graeme Williams

Graeme, I think I have 8 sets but since Chris started manufacturing I have stopped searching....
Bob Beaumont

What Guy said. I noticed a little bit of rattling and feared for the dreaded FWBs. Turned out I have slight movement at the O/S inner TR balljoint.
Well worth a good coat of looking at.
Greybeard

Chaps

An addendum to this is a possible desire to replace the discs alone. The bearings may well be acceptable - as Guy says, the problem may well lie elsewhere.

Therefore, even if the inner race of the inner bearing were to remain on the stub after removing hub, and providing I collect all the bits and everything is kept clean, theorectically is there any reason why discs alone cannot be changed? Any further precautions I should take?

Mark O

Yes it is easy to change the disks. Bit of a nuisance if the inner bearing inner race stays behind as it then has to be removed and reassembled with the rest of the bearing before refitting. Or replaced with new. May be worth fitting a new oil seal anyway. The oil seal lip rides on the flange of the stub axle and eventually scores it. Sometimes a new seal can be fitted slightly further on so it gets an unmarked bit to seal against. Bad cases mean a new stub axle or fit a Speedisleve. Earlier models used a felt seal which didn't cause a wear groove.

When you fit the disk do clean up any rust off the contact surface of the hub. Deposits left there will cause the disc to run out of true and give symptoms like a warped disc. Wire brush in a mini grinder does a good job but needs care in handling and it's essential to use eye protection.
Guy W

My sincere thanks Guy...much appreciated.
Mark O

hi .
had a look at mine today and play goes with foot on brake so looks like bearing. not that bad, looked on web sites which says there is an acceptable amount of play up to 1/8 inch at rim. think ill leave mine and see what mot pulls up. i have a while yet.
thanks bob.
bob taylor

Good Evening All,

Our SKF bearings are the ones , and they are stocked by MGOC.

Best regards,

Chris Buckenham
C H Buckenham

Does anyone else stock them Chris?
Graeme Williams

Graeme - direct from Chris' company
http://heritagecarparts.com/manufacturer/mg/midget/
David Smith

Hi guys,



Used bearings from Chris recently and they fitted perfectly, well worth the money get something decent.



Job was done in 30 mins.



Regards Steve
SR Smith 1

But it would be useful to know who else sells the "genuine" item as other suppliers will still be selling non-standard bearings but claiming they are to spec.
Graeme Williams

Graeme, personally I can't see why anyone would want to go elsewhere when you can go direct to Chris. Apart from mgoc I think he said he was supplying one other outfit but can't remember who it was, possibly Beech Hill garage, but may be wrong.

Trev
Trevor Mason

I know there has been a monster thread about wheel bearings in the recent past, involving discussions about face adjusted and radius variations, but, Moss are selling bearings, either individually or in kits for all models, including tapered roller bearings for between £20 and £26 per corner.
Are they any good, or are they what Dave O' mentioned earlier in the thread. Ess Aitch One Tee Ee?

Reason I ask, is I have MOT on Tuesday and there is a bit of play in one side, so if it fails I will be looking for new bearings.
Bernie Higginson

Good Evening All,

There really is little to say on this matter, MGOC and Beech Hill amongst others are stockists and I'm sure will more than happily supply all with a set of SKF Bearings that have the well known modification to the inner bearing .

On the matter of Taper Roller Bearings , this is really very straight forwards as well. Standard off the shelf geometry taper roller bearings will NOT fit Midget hubs and work properly. The geometry of standard off the shelf taper roller bearings will upset the various other offsets of your hub, i.e. Brakes. There is I understand a first class solution on the market for people who would like standard taper roller bearings made by JL Heap ( as far as I know) which is renowned for being well engineered and able to use taper roller bearings. It costs some money , but does address the issues because it appears to correct the problems of standard taper roller bearing geometry by using a custom hub, and as I understand it this is the only real way of doing it unless !!! You go out and purchase an enormous number of CUSTOM manufactured and dimensioned taper roller bearings from a bearing manufacturer.

Recently I was sent an aftermarket taper roller bearing kit and it was of standard dimensions , not custom to suit the job in the standard hub, so maybe useable but not really correct as far as I understand.

I'm very interested in what other people think.

Best regards,

Chris
C H Buckenham

Hi Chris, thanks for the . Indeed we produce alloy versions of the original Midget hubs but with 'off the shelf' taper roller bearings. We sell across the board from std Midgets to full blown racers, and have been doing so for 2-3 years now. Ourdisc kits utilise the same bearings but in bespoke hubs which take Ford discs and 4 pot billet callipers. These kits are a development of our long standing Minor kits which we have sold for 24 years now.
The benefits of the std hub are, 2 kilo weight saving, adjustable taper rollers as per modern cars and cheap components. A fully made up pair of hubs are £240 plus vat, good value in my opinion.


J L HEAP

""adjustable taper rollers as per modern cars""

Sorry couldn't resist but which modern cars use taper rollers in the front hubs? Most I have had to bits use the twin row balls which are basically the same as the Spridget/Minor but with preset loading instead of using a separate spacer and adjusted bearing faces. Others use a variety of modern bearings but I have not seen a adjustable tapers?
Robert (Bob) Midget Turbo

Adjustable in the meaning that they can be adjusted , rather than being adjustable bearings. i.e. no centre spacer required. My bad saying modern cars, I shall go beat myself mercilessly so I make no more fopars.
J L HEAP

Hi no problems but the point is that modern bearings are not adjustable, The last adjustable bearings I had were rear wheel bearings in a variety of FWD cars including the Ford Fiesta which of course were far cheaper than modern preloaded bearings but inferior quality and engineering
Robert (Bob) Midget Turbo

Tevor: the reason it's useful to know other suppliers is because quite often I find I need to buy several items. If one item was a front wheel bearing set, to be able to buy from the same supplier who could provide the other parts I needed would make a substantial saving on post.

I do get p*ss*d off having to buy some inexpensive part and pay twice the value in postage! I maintain a list of items (gaskets etc) I need to buy next time I order something substantial. I'm sure I'm not alone in doing that.

Graeme Williams

Chris. I'm not for one minute disputing what you say about taper bearings being unsuitable for Spridgets, but Moss make no mention of the taper roller bearings needing any kind of modification to them or the hub, so how can they be selling them as an option to normal ball bearings? Have they discovered some that will fit?
I'll have to pay them a visit.
Bernie Higginson

I think the issue with taper rollers in std Midget hubs is the radius,on the stub axle, i.e. the need for face adjusted bearings.
Taper rollers do not incorporate this adjustment so will not sit correctly on the stub axle, which in turn will throw out the spacer should you use it . Our kit has a 2mm spacer which sits against the radius on the stub axle and converts it to a std 90 degree fitting common in taper roller bearings. The bearing therefore is mounted slightly more inboard in the hub than it is on our Minor hubs, this in turn keeps the correct alignment of the hub,disc and callipers, and therefore a simple direct replacement for the original set up.
J L HEAP

<<I think the issue with taper rollers in std Midget hubs is the radius,on the stub axle, i.e. the need for face adjusted bearings. >>

The radius is a separate issue, nothing to do with the face adjusted bearings.
Dave O'Neill 2

My understanding is that the radius on the stub axle required a bearing with a suitable reciprocal radius (standard set up ). Therefore a taper roller bearing which does not have this feature , will not seat correctly and in effect push the hub outwards.

Is this incorrect ?
J L HEAP

If the hubs are pushed outwards, it is only a little bit. The alignment of the brake pads with the disc would be out by that much but the first time you step on the pedal the pistons and pads self-align against the disc. I ran tapered roller bearings for years without a spacer or the proper radius and the only problem that I had was removing the inner bearing from the hub. Since there was a slight gap there, all it took was gently applying a wedge (screwdriver) and off they came. I currently am using face adjusted bearing without the proper radius and to make it easier to remove them, I've made a spacer that is .006" thick which is about 2mm. It has been a number of years and I haven't had any problems pulling the hub and bearings as a complete assembly.
Martin Washington

Thankyou Martin, the gap left is 1mm. The issues you experienced are best engineered out at the outset of designing a bespoke set up. We have both done the same, but in slightly different ways and with the same results.
J L HEAP

Since I don't have a machine shop in my shed, I worked with what I had available at the time. It took a bit of thinking but as you said, same results that I'm happy with.
Martin Washington

Bernie,

I can't comment on any of the main manufacturers taper roller products , other than the Heap conversion that addresses the issues as I understand them.

From our own investigation we have found that, as we understand it, even with the radius cut on the inner bearing a standard taper roller won't quite do the job. And on the basis that JL Heap really do look like they've solved the issues with their method for anybody who wants the taper roller set up I tend to feel that there is evidence that it is wise to consider that approach. I think I'd look like a bit of a pratt if we just offered radius modified standard bearings, even if they were high quality with a higher than average price to match.

Best regards,

Chris
C H Buckenham

I think it should be said that

1 Guy has given the best advice in the matter of the movement etcetera: Check first before you leap, 'cos the bearings are least likely to be the seat of the problem

2 Chris has given us the best replacement for what we should have been able to buy from the shops, but haven't

3 Jonathan's people have re-engineered the setup to give us a decent improvement

I used Chris's bearings to good effect recently but having a badly knackered hub on one side of my car the proper setup failed and I had to do the old fashioned fettling to make it work

Fortunately my rebuilt bearings have worked very well, but the set from Chris just slipped into their hub perfectly

Consider this an endorsement for them if you will


I should have obtained a non knackered hub from PBW or one of the other spare parts sellers, but as usual I didn't leave myself enough time before the MOT was due


:-(
Bill sdgpM

I first became aware of the problems caused by the stub shaft radius about 5 years ago. How I discovered it was I could not fit new brake pads because everything was so far off centre that one pad on one side was thicker than the gap.
Although the bearings which had been fitted by the po were correct, he had fitted them the wrong way around so the generous radius was on the spacer side.
Graeme Williams

Chaps

Pursuant to the advice, I fear it may be a worn bottom kingpin bush. Disassembly looks straightforward, bar all the horrible rusty fastenings, but removing/replacing the bushes looks fraught with all manner of reaming, heatimg, persuading and all round hassle. Is this indeed the case, and am I best advised to take the hub/kingpin assy and new bushes to my local friendly machinist?
Mark O

The other option is an exchange unit which I think Moss and others supply.

Bob Beaumont

If the kingpin itself, and the fulcrum bushes in the wishbone are OK, then as Bob says, the easy solution is the exchange hub carrier.

If the wishbone bushes are also worn - which is the commonest weak point, then the bit that is often difficult is to disassemble that joint. There is a tiny cotter pin to drift out and then the fulcrum pin is often seized to the king pin. With care you can cut the fulcrum pin either side of the kingpin knuckle, dismantle and then drift the stub out. Use a slitting disk in a mini grinder or a power hacksaw as the pin is quit hard. But again, exchange wishbone/fulcrum pin and kingpin sets are available - at a price!

But first - is there vertical movement on the hub carrier/ king pin? If so this can be reduced by removing shims at the top of the king pin. This may be enough to reduce the lateral movement at the bottom king pin bush. Especially if this is then also pumped full of fresh grease. This is often enough to give the whole assembly a new lease of life, and sufficient for the MOT test
GuyW

Chaps

To put this in perspective somewhat, the movement does seem to be at the base of the kingpin. It is very slight, but there is the faintest audible click when wheel is rocked back and forth on the axle at the vertical position. On placing finger on the base of the stub axle body, and on the kingpin just above the knuckle I can feel a slight movement of the axle body.

The whole replacement bush job looks to be a royal pain, and I am interested therefore in Guys possible alternative of removing shims and pumping full of grease. Even though I cannot detect any vertical movement, it may be worth a try.

Is this therefore a case of simply removing the suspension arm and trunnion and subsequently removing the shim or shims?

I had also intended to replace the existing bearings with new correctly face machined items. I guess this would help matters further.
Mark O

Yes it is just a matter of disconnecting the shock absorber and taking off the top trunnion. Be careful, removing shims or shim may result in the stub axle not moving freely when the top trunnion nut is done up tight. The shim really only is there to regulate vertical movement of the stub axle on the king pin.

Apparent wear on the lower bush is not unusual. I have found that renewing the king pin can solve the problem. The pin can corrode due to water ingress. it still means a faff of course!!
Bob Beaumont

Yes removing the shims adjusts for vertical play and this may reduce the movement at the base of the kingpin. But as Bob says, be careful not to overdo it and make the steering stiff.

I have lost track of where this started but thought that you said there was a rattle which you initially put down to worn wheel bearings. Or was that someone else on another thread? The slight click now described may cause a rattle in use, but I think if it is audible on the road it may be something else. Unless there is more movement there than you describe.


GuyW

Guy/Bob

Many thanks again. Yes, I did say rattle but seemingly of the pads rather than the bearing itself, especially when it goes round a left hander. I thought the rattle may be a consequence of bearings though - guess it may be a consequence of the kingpin instead.

The play really is very small, and I am wondering whether I am being over zealous and putting 2 and 2 together and making 5. I will try removing a shim and see if it improves matters.


Mark O

If removing shims then jack both front wheels off the ground and prop the chassis on axle stands. Check that you can twirl the steering fully lock to lock. Then put a jack under the bottom wishbone on the offending side and jack it up to the point that the weight just begins to transfer from the axle stand on that side onto the jack. This will take the tension of the road spring off the kingpin and you can safely undo the castellated nut.

Very gently lower the jack just enough - and no more - to ease the top of the king pin out of the trunnion whilst lifting the damper lever arm as high as it will go. There should be no need to remove the trunnion itself from the damper lever arm. You will find some small shims that sit on the step in the kingpin, just below the threaded section. Try removing one or more shims depending on what you find.

Pump the jack up (I use an hydraulic bottle jack for these sorts of jobs which gives good control)whilst guiding the kingpin back through the phosphor bronze washer and into the trunnion. Pull it up by tightening the castellated nut and nip it tight. Now remove the jack and test for free steering movement and also see if it has improoved the slack. If steering is tight, then you have removed too many shims and you may have to backtrack a bit. Its just trial and error at this stage.

Sounds complicated, but it is safe and easy to do so long as you use a controllable jack firmly placed under the wishbone or better still, inserted up into the lower spring cone. There is no need at all to do anything more to manage the road spring tension than I have described. If others start talking about removing the spring with long bolts etc, etc, then that is all quite unnecessary for this particular "adjustment"!
GuyW

PS:
NB vertical play is NOT achieved by slackening or adjusting the castellated nut, but by the selected shim pack, so that nut does need to be tight.
GuyW

Once you take the tension off the king pin by the lower jack and have disconnected the top trunnion, you will be able to check more easily if the kin pin/bushes are worn by shaking the stub axle. As I have said its usually the lower bush that wears.

Also If you lower the jack you should be able to slide the stub axle up the king pin revealing the lower portion of the pin. You can then check its condition. It should be bright and shiny. if its rusty or looks corroded then the answer is an overhaul!
Bob Beaumont

notr that the shims are frequently stuck inside the trunnion, I use a dental pick to extract them.
David Smith

Chaps

We are not worthy......will keep you posted....

Profuse thanks...

Mark O

This thread was discussed between 22/02/2016 and 07/03/2016

MG Midget and Sprite Technical index

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