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MG Midget and Sprite Technical - fwb - play time

So a mate fitted the NOS RHP fwb at his home garage whilst I cleaned stuff and confirmed what was written.

Norm's instructions - (outer bearing) "Confirm it is FULLY driven home by measuring the distance from the inner race to the "shelf" that the inner bearing seats against. This should be 1.496" ~ 1.498". If you get more than 1.500", your bearings will be crushed by the hub nut torque and have a short life".

The measurement we got was 4-5 thou more than this using engineering type measuring tools.

The new outer bearing was removed to check there were no high spots or ridges in the hub, none were seen.

As no other hub was available and AFAIK this hub was on the car when I bought it nearly 12 years ago we decided that it would have to be used.

The spacer that came out measured 1.49" with an electronic vernier but the new one was checked at 1.5" previously.

Reassembled and road wheel back on there was still play and some sort of noise when driving whether it is from the fwb area was unsure.

At my home I tried a different castellated nut to get a different torque when aligning the split pin. Test drive, no determinable difference.

Back to my mates, castellated nut off again to check the tabbed washer was free to fully sit in position and it was and use of torque wrench confirmed there was slightly less using the new castellated nut.

Any ideas?

Easy to feel movement in the road wheel with the car is just parked up normally but goes solid with brake pedal pushed.

The bearings that came out looked OK but were well covered in black grease, no visible markings on them for make and part number suggesting they were First Line ones but I've never seen the (post prototype) Meditech ones in the metal.

Another reason for having a more knowledgeable mate for what was supposed to be him looking over my shoulder whilst I done the work was to see if there were any other noticeable faults to the kingpin, stub axle and area generally but none were noticed and that items were safe to use and this was confirmed.

I can't remember from when but at some stage my front wheels have negative camber of IIRC 3.5 and 4.

I've only noticed the noise and play in the n/s front wheel this year.

What does the team think?
Nigel Atkins

First always ensure that where you are driving bearings into is clean and ready to receive them.

Ensure the bearings go in square - you can tell by noise and feel through the drift when they have bottomed out.

Measuring hubs with accuracy is difficult due to acccess and ensuring the instruments are true/vertical to whats being measured etc + Quality of many Digital calipers etc. I wouldn't have bothered - there are millions of them out there and I doubt that any BMC garage checked them !

If you have play why not replace the original spacer as you believe its undersize ? (again need really accurate measuring).

You can then check for bearing play before fitting the caliper - does it still run free ? - just replace the road wheel and rock it side to side.

You should be able to feel if the old bearings are shot by rotating them by hand and feeling for a rough / gritty feel.

If you still have noises, need a good check while turning the wheels - anything rubbing ? wheel weights loose etc and is it actually from the NSF ?

R.
richard b

Hi Richard, thanks for your reply.

The hub was checked for being clean and no unwanted additional layer of anything.

Noise and feel of bearings seating was good first and second attempt, we had appropriate equipment to hand. :)

There was no way I would have been able to measure or see any measurement we were just following Norm's written instructions. I too worry about the accuracy of a venier but a micrometer with different rods was used by dropping something down to get a wider stable base then deducting the depth of the something (forget what it was). The gap was 4-5 thou too wide.

We too thought there was no way a garage would put in the effort we were.

The spacer used wasn't undersized it was checked at 1.5", it was the one that was previously fitted that was undersized, it looked like a new one fitted last time but I've no idea how you'd be able to give them an age. There was some irregular marking on the outside at the thicker end, no idea what from.

My thought was to get the (previous) spacer (not currently fitted) shortened to allow for a sensible depth shim (washer?) to be used to take up the slack.

If that's 4-5 thou slack then I'd probably be able to tell 2 thou on the road wheel.

Just that new bearings are in but the same problem remains and that this problem only appeared quite recently yet the previous bearings and spacer have been in for 3-4 years.

If there was no slack in the wheel I'd worry about the noise later or if it got worse, certainly not sure it's n/s/f and it doesn't really sound like the noise I've had before with failing wheel bearings. When you start to listen hard you can imagine all sorts of things it might be. At one time the car goes a whistle at the front I couldn't work out why then at some stage it disappeared, again no idea why. As long as things are safe I don't worry too much about odd noises, they could be one, two, lots more just creating a cacophony. Normally I don't hear much over the exhaust.
Nigel Atkins

Nigel,

If your measurements of the original spacer are correct ?
it is already 10thou undersize - I would still recheck by measuring onto a faceplate (or sheet of thick glass etc) with a gauge of known accuracy and ensuring it is vertical etc.

If you have a lot of play it may be worth fitting the old spacer and taking up the bearing nut slowly and see if the bearing locks or if you can achieve the torque setting with a nicely free rotating hub.

Something does not add up with all the measuring as according to what you noted from Normans figures the hub should currently be tight/solid or have no play.

As you have RHP bearings it should all go together as intended by BMC with no measuring at all.
richard b

Yes I'm all for cross-checking with different instruments but I only have a tape measure and wonky eye so have to rely on my mate but he does work at a place that does work for Jag and Aston engines so he should be able to recheck the previously fitted spacer for 1.49".

I can't think now if we were on our ar*es or elbows as we (mainly my mate) checked and rechecked and crossed checked several things including swinging torque wrench and me my cheap torque bar that I only use really for wheel nuts or if I need a long handle for leverage (turned out my bar was reasonably accurate).

From getting there to hub and wheel back on was around three hours so although we weren't rushing you can guess it allows a lot of time for checking and head scratching.

After this would have been another hour of investigating at least, it was like castellated nuts and split pins were going out of fashion.

He can't recheck the new/current spacer which was measure at 1.5" or the hub gap as those are on the car. I can't dump my car in his garage as he wants the space (selfish devil) so I need to have the wheel fitted to my car to get it to my home. Today was far too windy, wet and cold here to piss about with cars in the open air.

I'm with you that something is really amiss, this play (and perhaps noise) seemed to appeared quite suddenly - mind you the state of the roads around here could swallow up the midget front end in one piece.
Nigel Atkins

just a thought and i know its a bit of work but could you swap sides with the hubs and see if the problem moves sides then you have an idea which parts are wrong , or try another hub i had one that the bearing was a loose fit in the hub when i tried a different hub the play disapeared.
mark heyworth

My mate usually has/had a few old parts knocking about but not a hub.

If I had the time I might have tried swapping over sides, but tbh I didn't think of it, and you can only use up so much of some else's lifetime. You have though just reminded me that I was going to move the wheels around to see if that made any difference to the sound (thinking of wheels/tyres more there).

But these things never happen at convenient times and it's a mystery why it has suddenly become so noticeable (as a fault rather than cause).

My concern was that it might involve parts like kingpins or wishbones where new parts might be poor quality and not wanting to rely on s/h parts or try to remove parts and fittings that might get damaged.

The brake pads came out this time, and got new anti-squeal pads, not seen or took the pads out before to lift the caliper off.

Doing extra work can often save time but it is at the risk of finding or creating more problems which adds to the job time and/or parts required which is fine if the car can sit in pieces for parts to arrive or a more convenient time to do the work and the car and space it occupies aren't needed for other things.
Nigel Atkins

A bit obvious, but the bearing did go in the right way round I hope?
GuyW

Something like that is always possible but I had prepared four different A4 sized pages of notes and illustrations. Three of these were emailed to my mate first then printed off and left with the spacer for size checking a week before installation. I realise that those in engineering don't like reading notes but they do look at drawings. I took another full set of four with me on the day, parts of these were at least consulted then as I read off conformations as a check when things didn't measure right. The RHP bearings are also marked THRUST so if it was put in wrong way round first time it should have been picked up on second installation - but when things aren't as they should be you do start doubting yourself.

If it hadn't have been in Norm's notes measuring the gap wouldn't have been thought of as the bearing went solidly home.



Nigel Atkins

If you have a dial indicator , mount it up and get an actual end play measurement on the hub and then adjust the shim to suit
yes-no
willy
William Revit

So which way were the thrust markings on each bearing when fitted?
GuyW

There must be another explanation. The genuine bearings have always been a simple fit and I have never experienced play or noise. I admit to not being that particular about measuring the spacer, just re-using what's there. I used to replace the bearings regularly in the race car back in the 80's as they struggled with wider slick tyres (before I fitted tapers)and never had a problem.( happy days a set of RHP bearings then was just £5)
Bob Beaumont

I've not got a watch let alone dial indicator but I can ask around for one.

Thrust markings facing spacer - is that not right?

The inner bearing has to go with the 2mm radius to the axle so that shouldn't have got that wrong. Perhaps I misunderstood and made the notes wrong for the outer bearing.

The play was with the previous bearings too but only since this year some time and they have been fitted 3-4 years.

I thought it might be elsewhere but the wheel is solid if the brake is applied and I thought that meant wheel bearings(?).

I'm sure it will all have to be done again but obviously I want to get to the bottom of this to try to get it right before pulling it apart again.



Nigel Atkins

Nigel,

Silly question - were the bearings fitted the correct way round?

Please see attached picture (can't remember where I got it from, but it shows the bearing orientation very well).

Richard


Richard Wale

Hi Richard,
you probably got that from Norm's posting on the US site or it's original location.

As I've just put anyone can make a mistake but that information was available and my mate is used to this sort of thing being a B and daily Spridget owner for many years. He done his fwb 15 years ago, I can't remember if he user roller or not.

This is my amendment to Norm's -

(ETA: looks like there's a difference and more detail to oil seal on mine so perhaps yours isn't from Norm)



Nigel Atkins

The other drawing I added to -


Nigel Atkins

Nigel, surely if the thrust markings are on the inner race of the bearings,then they need to face AWAY from the 1.5" spacer.
GuyW

The markings thrust on the bearing should always face the spacer.(as per the workshop manual) Any other way round and there is a danger the wheel coming off.
Bob Beaumont

ETA: Bob posted whilst I was looking for and editing photo.

The thrust markings are on the thick side of the outer wall of each bearing.

As an example for the larger inner bearing, the thrust side is the face on the opposite side of the bearing to the 2mm radius.

I've had my understanding of which way the bearings face to the spacer confirmed by an outside source known to this BBS if not the Police.

From this source I am told that "the thrust markings are on the SAME side as the RHP and number markings, ON THE OUTER RACES". (capitals not mine)

Below are the actual bearings that were fitted.




Nigel Atkins

'The thrust markings are on the thick side of the outer wall of each bearing.'
And the discription works to identify thrust faces even if not actually marked (other makes etc).

As I noted before I would be of a mind to re- install the original spacer and carefully tighten up and check free rotation as I tighten/ torque up.

Or get a spare hub ! most hubs are unlikely to arrive with a servicable disc so enter problem 2 !
I find removing discs that have been on a while quite difficult due to corrosion.
I may have a spare hub in the sheds if all else fails !
richard b

Hi Richard, thanks a lot I think I'll do as has been suggested and work (well not me) with what I have. After the NEC the hub can come off and my mate said he can measure it better and cut or shim the spacer as required (he has access to the necessary equipment).

I've had the brake dics replaced twice, first time was with another mate, o/s fwb was changed then too, they went on to existing hubs and last time was at fwb garage so I've no idea what might have happened.
Nigel Atkins

I just checked my Haynes manual and it mentions what I recall. The thrust marking may be on the outer race in which case they go towards the spacer or the thrust marking may be on the inner race in which case they face outwards.
David Billington

Good point David.

I think I amended the drawings ready for the previous Meditech bearings installation but I might be wrong.

I'm not a fan of Haynes so don't refer to then too much - my 1982 edition has the same as yours but my 1974 edition (that doesn't fully cover my 1973 car anyway) has -
"The sides marked 'thrust' on the inner and outer bearings must face towards the bearing distance piece."

The (1972) copy of the factory Workshop Manual I have has -
"Ensure the bearings are fitted with their thrust side adjacent to the bearing spacer".
Nigel Atkins

Some don't have the word thrust on them. The easy way is to look at the outer race of each bearing and the broader faced rims go back to back into the hub, or towards the spacer. Conversely, the broader faced of the inner race Face away from each other
You can also verify this by feel as the balls nestle into the races as the bearing turns.
GuyW

In the interest of further accuracy (and more importantly to get this fwb thread to a more appropriate post count) I've just noticed the bearings I have are marked 'R&M' not 'RHP'.

(I can be a little forgetful at times.)
Nigel Atkins

These photos Lawrence sent me today illustrate what Guy has wrote. -



Nigel Atkins

I think some of the confusion arises because of the words used, I.e. we have two bearings, an inside one and an outside one and an inner and outer race to each bearing. I think some people using inner and outer bearing gets confused with races.

Nigel, purely for historical accuracy R&M and RHP are one and the same. Originally there were three companies, namely Ransome and Marles, Hoffmann and Pollards. The companies were merged to form RHP or Ransome Hoffmann Pollard to give them its proper title.

Trev
T Mason

Guy,

That's my recollection as well, I've fitted quite a few that had no obvious thrust indication but always found on examining the bearings that the orientation was obvious, it might help though that I'm an engineer and understand how they work.
David Billington

david, I am not an engineer, but a reasonable amount of common sense and thought about how the components fit together, and what holds them in their relative positions will give the correct answer.
I wasn't really doubting Nigel (or anyone else for that matter) when I first asked if he was certain they went in the right way round - I was just casting around for something that could explain why he still had apparent slack and noise from the new bearings
GuyW

Completely in the dark here but...

Given what else has been measured, the old and new bearings are the same thickness?

Thinking about past (lengthy) threads on bearings, same radius?

Regards
Roger

R Taylor

Hi Roger, c'mon in.
I've no idea about if there are significant differences in thickness, you'd hope not but who knows, the new bearings fitted are NOS original spec with the 2mm and "face-adjusted".

Guy,
you'd always be very wise to check if I've done anything mechanical on a car whether it is correct. I'm not certain if all the noise or any part of it is from the fwbs, it could be but to me it's not exactly how previous wheel bearing noises, on this and other cars, have sounded.

I've been helped to the conclusion that these associated parts don't marry together with the precision that Norm might have credited them with.

Nigel Atkins

G'day Nigel,

Lord that was a quick response - you're supposed to be asleep!

Roger
R Taylor

Trev,
sorry missed your post, thank you for the reminder on the history and explanation of the names and initials, I had forgotten.
Nigel Atkins

Nigel-Could you please say hello to Lawrence for me next time you have contact
willy
William Revit

could it be that while they are the correct bearings by basic part number they are not the face-adjusted variety that our cars require?
David Smith

Roger I saw your post just as I was about to switch the machine off.
Nigel Atkins

Willy,
next time I have the ouija board out I'll see if I can contact the evil spirit again.
Nigel Atkins

It's easy enough to check if they are face adjusted before fitting the bearings. And if not and you want accurate installation then either use of shims or lapping of the spacer will get it right.
GuyW

David,
I thought these were the face-adjusted parts hence the effort to chase them down after the Meditech supply ceasing. The idea of having the Meditech sets fitted last time was to not to have to be involved with this again but of course that didn't fully work out.

I've had the 1mm non face-adjusted sets on my car previously, before being made aware of such matters and they fitted without noticeable play, initially at least and have lasted x-miles and y-time until the MoT tester makes comment.

It seems that the requirement for the spacer to be exactly 1.5" may not tie in with a good fit to the particular hub and that the spacers are not always 1.5" any way. But without going through a large stock of spacers with a scientific certificated measuring instrument I don't know and don't know the allowable manufacturing tolerance. Norm's notes have 2 thou.
Nigel Atkins

Guy,
so what the check?

Is lapping it let it sit on your lap, I just have the spacer shortened. :)

Lapping it, next it'll need stroking - but I bet that stroking means something different as an engineering term. :)

Nigel Atkins

We are in danger of going round in circles.The image Nigel has posted of the bearings used indicate the correct bearing numbers. There should be no need to adjust the spacer. There is another problem if the hub is loose on the stub axle. They are both marked thrust and this face should face the spacer. Either the hub itself is faulty or the bearings have been incorrectly assembled in the hub.
Bob Beaumont

Mark's idea of swapping the hubs from one side of car to the other would start to pin things down.

If I could line up a row of Spridgets I could now tell how much more play is on mine to compared to others. I think I could now possibly detect 2 thou, other people may be able to got to 1 thou or less, bigger or denser muscles may help.

The other side of my car seems OK but I'm not even as strong as I used to be, physically I mean.
Nigel Atkins

Guy,
I've seen various references to shimming the bearing /tube spacer, but as they need to be clamped together to form the 'pipe structure' often refered to, how is the shimming carried out ?

As far as I can see it would require initial assembly with excessive shims (spacer having been reduced in length) - measuring the end float and dis-assembly and remove excess shims to give the required small amount of float. However with the possibility of sticky inner bearings on the axle is there not a high risk of destroying the new bearings ? or am I just missing something ? (nothing new there !!!)

Obviously with a taper set up such as the MGB it is relatively straight forward as I have previously carried out. Note an MGB notes 2-4 thou end float required).

I think we also need our 'Eastern correspondant' to assist and comment on home face adjusting !
richard b

Nigel,
If you had a set of Meditech bearings they would be SKF marked.
ISTR his earlier trials were with non face adjusted - with a bespoke spacer supplied to suit each bearing set. He did grind the required inner radius.

After comments on the BBS about confusion if his spacers were used later in life of the vehicle etc he managed to source at a good price face adjusted units that didn't require the spacer faff only the inner radius altering.

Did you end up with one of his early trial sets (ISTR theese were offered free for comment) or a later bearing only set - as this could answer why you have measured a reduced spacer.

If they are not SKF well who knows (but you ?)
richard b

As I understand it, the bearing recesses in the hubs are machined such that the spacing, back to back is 1.5" I don't know what the tolerance on this would be but there must have been some variation. The spacer tube is also manufactured to 1.5", give or take. With "face adjusted" bearings the distance between the surface of the two outer races (marked "Thrust") should be the same as the distance between the two similar faces of the inner races so that they also clamp up tightly against the 1.5" spacer tube.

In theory that is a very simple thing to achieve. But I do recall reading that in the factory assembly, if a hub set was assembled and was found to be loose, then they simply removed the nut, outer bearing and tube and grabbed another tube out of the parts bin. Presumably there was enough tolerance that matching a different pair of hub and tube woud be likely to give a different degree of end float.

If one was doing the same with non face-adjusted bearings a start would be to check with a straight edge laid across the diameter of each bearing on the thrust side. Held up to the light, with the races pushed firmly together, but not crushed, one would readily see if the inner race surface was proud of, or recessed, as compared to the thrust surface of the outer race. An appreciable difference could be measured and shims selected for the combined calculation for the bearing pair. This may be a bit basic but one could reduce any movement at the wheel rim to an acceptably small amount. Care would be needed not to over-shim and crush the bearings which would be worse than having a little too much free play.
GuyW

Funny you mention holding up bearings to a light to check for variances of face adustment etc - I was doing that last week !
I found a source of inners that were listed as OE spec - they have the correct 2mm radius (I've made a gauge ! - some RHP ones I have seem to have a slightly bigger radius).

I don't think you would get a satisfactory final measurement of end float without fully assembling and torquing up, with a DTI check to finalise shimming - hence the need to strip and re-assemble - as per MGB handbook.

I assume you meant avoiding under shimming to avoid crushing - if the shims are fitted to the spacer.

From Norms figures float is noted as again 2-4 thou if all fits correctly ! (as per MGB WSM)
richard b

Hi Richard,
no I didn’t take advantage of the free sets on offer as I woouldn’t have been able to report on them as I wouldn’t know enough, plus the bearing sets that were in the wheels at that time were working and I didn’t want to tempt fate, also of course by Sod’s Law if I had fitted a trial set something would have gone wrong – excess play perhaps – and I wouldn’t know if it was the trial bearings, the fitting, the spacer, the hubs, the phase of the moon, etc, etc.

For no good reason I thought the plastic races in the Meditech were blue, but I’ve never seen them as I had them delivered straight to the garage IIRC, two sets but one set “broke” so I’m guessing a First Line set was fitted to replace the broken set. I can’t remember what a First Line set looks like as the previous sets were fitted in the halcyon days of just fitting fwbs without all the current sourcing, preparation and worry. But I’m only guessing they might be First Line as the ones that came out were without manufacturing information.

I left the bearing set that came out this time with my mate if he still has them I’ll clean them up a bit and post a photo perhaps next week.

Oh for the joy of the good old days when all that was required to fit the fwbs was a 4” nail and 2lb lump hammer.
Nigel Atkins

Richard, quite right about too few shims causing crushing. I would like to congratulate you on spotting the deliberate error. But it wouldn't be true. The deliberate bit I mean!
Thank you for clarifying.
GuyW

This is a copy of my post in the earlier thread on 'OE Wheel Bearings':

'I got fed up with the combination of new bearings and decades old hubs and spacers resulting in unpredictable overall dimensions, so decided to follow part of the front hub design from the MGB. That uses taper roller bearings, with shims and a solid spacer to achieve the correct end-float when the hub nut is tightened, and the inner bearing races clamped.

The MGB uses the additional stub axle strength gained from the clamped inner races and spacers, in the same way as a Sprite/Midget, Minor, A35 etc.

I did not want to lose that added strength by going the 'loose' taper roller route, so bought a selection of MGB front hub shims, and after machining ~0.010" (not critical) off the spacer length, I selected the appropriate shims to get the required pre-load.

A Minor does not have the same size root radius at the end of the stub axle, so OEM spec face-adjusted bearings are available at not too silly prices.

The same could be done with a taper roller conversion as well.'

To be able to shim the bearings to get the correct pre-load that a Midget/Minor etc. needs, as opposed to end float for the MGB, the spacer has to be machined to REDUCE the length - I machined 0.010" on mine, but the exact amount is not critical, and the final pre-load is determined by the shims used.

I can't help feeling that although lower tolerance non-face-adjusted bearings can/will cause problems, that it can easily be caused by wear in the hub, which reduces the clamping force, whereas were of the spacer will increase the clamping.

Richard
Richard Wale

Having noticed a spelling mistake in the previous post, I cannot change it as I have had my allotted 5 minutes!

Does anyone else find this a bit short?

The Morris Minor forum used to allow editing at any time, and then reduced it to 1 hour - that caused much complaining, so it is now 24 hours. Even then re-reading a post later sometimes prompts a need for more clarity.

Richard
Richard Wale

The problem with longer edit times is that history can then be 're-written!

People can write things and then deny that is what they said, or it simply encourages sloppy messaging.

I usually write, 're-read, correct and then post immediately. The 5 mins only starts from when the message uploads so if you read your message when it appears if necessary you still have a full 5 minutes to correct, which is surely ample in most cases.

For longer or more complex messages I write them in a word document, spell check and then simply cut, paste and submit on the BBS.

Mistakes will still get through but does it really matter?
GuyW

Richard, I've been asked to put up a comment about a mistake you've made, I missed it and didn't fully understand the subject then (and not fully now). -

“To be able to shim the bearings to get the correct pre-load that a Midget/Minor etc. needs, as opposed to end float for the MGB, the spacer has to be machined to REDUCE the length - I machined 0.010" on mine, but the exact amount is not critical, and the final pre-load is determined by the shims used.”

The design calls for the exact amount of clearance not pre-load.

The Morris Minor does not actually need the spacer if going the taper route. The Minor stub axle spindle is inserted, that’s why it doesn’t have the radius. As a result it doesn’t have the stress riser that requires the pipe effect to stiffen the spindle.
Nigel Atkins

Nigel,

I have never seen any reference to front hub 'clearance' on any north/south A-Series engined car - where does it come from? MGB yes, but not Midget etc.

The Sprite, Midget, Minor, A35, A40 etc. front hubs all are designed to have a small amount of 'pre-load' on the standard bearings. The amount is determined by the back-to-back dimension between the outer bearing races (controlled by the hub), and the back-to-back dimension between the inner races (controlled by the spacer). Any 'end float' is very likely to result in an MOT advisory at best. There is not supposed to be any.

The nominal dimension for both hub faces and spacer length is 1.500", and the original design is intended to have the spacer very slightly shorter than the distance between the 2 faces inside the hub - the difference between the two is designed to create a 'pre-load', which is good, but after many miles, more often 'end float' which is not!

The bearings are ‘face adjusted’, which means that the overall thickness tolerance is more closely controlled, so that the design pre-load can actually be achieved in a production environment, without the need for ‘selective assembly’.

The hub nut is tightened on to the inner races and the spacer, which firstly controls the inner race 'back-to-back' dimension, and secondly adds some strength to the stub axle. Removing the spacer to fit taper roller bearings loses this added strength.

The idea of using MGB shims came when we were working on my son's MGB, which has taper roller front bearings, but with a spacer and shims to get the designed 'end float' after fully tightening the hub nut. The MGB design is unusual, as normally hubs with taper roller bearings adjust the castellated nut to get the required end float.

Yes, the Minor stub axle does not have the radius at the inner end, but whether the strengthening spacer can simply be discarded is not a direction I want to go.

Using the spacer and shims to get either the required pre-load for the standard angular contact bearings, or the designated end float for taper roller bearings, is a very simple and predictable solution. Relying on everything being exactly to dimensional specification becomes a thing of the past – just use the shims to get whatever is required.

Richard
Richard Wale

Hi Richard,
we could get into some very long post here.

I'm not 100% sure who's right and who's wrong and with what and how much.

I do know following Norm's instructions wasn't right as far as I can tell.

Are you able please to quote the source for the pre-load.

I've seen mention of pre-load but the wording around it isn't precise to it's meaning within the FWBs and stub axle.

Originally with these bearings and spacer it was "not essential" to torque the hub nut but my 1972 WSM has 25-65lb ft - having said that Bob tells me the Mk1 Sprite manual called for annual greasing of the outer bearing yet my good book has greasing the front suspension "excluding hubs", so requirements did change other the years.

The original illustration I've seen calls for the inner race to be recessed by no more than 1 thou inch, not proud by no more than 1 thou inch.

Are you saying that the spindle spacer should be shorter than the distance between the hubs. If that were the case, then that would make the inner race of the bearing sit proud of the outer race, the exact opposite of the what I've seen.

If you want I can post up BOB Midget Turbo's explanatory post on FWBs and drawing from one of the infamous previous threads on the subject of FWBs (?).
Nigel Atkins

Nigel, the torque of the axle nut has no effect on the bearing pre-load or free clearance on the bearings of a midget. It serves only to clamp the inner races of the two bearings and the bearing spacer together so that they act as a single unit, providing the additional supporting strength needed for the axle.

Clearance or pre-load is ONLY a function of the difference between the spacer, bearing characteristic (face adjusted or otherwise) and the machined back to back clearance of the outer race seatings in the hub.

Use of face adjusted bearings by the factory was simply an expedient to cut down variability so that no setting up was required on the production line. But in the absence of face adjusted components the same tolerance can be achieved with shims or by lapping the spacer
It just takes longer and more precision.
GuyW

Thanks for that Guy, my head is spinning, but a good reminder of what I should already know but keep forgetting. It's like a court case where I'm a juror swing from one decision to another.

Are you saying the bearing set up is about clearance rather than pre-load?

I wondered why bother putting up a torque figure or range in the later books if the nut is secured with a pin anyway. The car's got heavier and faster, yes, but 25 and then up to 65 is beyond what's needed to get to the next clear slot on the nut as far as I've found.

I had fitted NOS original 'face-adjusted' bearing sets yet the first spacer need to be shortened by 8 thou, the second I've yet to find out about.

The 8 thou came off a newly purchase spacer that was measure at 1.5" with an electronic vernier, it wasn't mine so I can't say about its strict accuracy.

The 8 thou of (whatever the actual length) was measured with a DTI mechanical clock.

I must come clean with you now - behind my quadruple garage I have a couple of sheds with my workbenches, vices, lathes, surface table, lapper and sets of DTI instruments ready for simple DIY classic car mechanical jobs like the simple and very straight changing of FWBs.

Sorry, couldn't resist. :)

Nigel Atkins

Guy,

Actually it does. Both the stub axle and spacer are elastic as are the bearing races, increasing the stub axle nut torque will stretch the stub axle but also slightly shorten the spacer due to it compressing so reducing the bearing clearances. I'm not about to try and calculate the overall effect though but it sounds like Nigel might have the kit to measure such changes with the right set-up.
David Billington

David,
so is there pre-load or clearance with the set up?

BTW I was joking, I have no garage just about 15 foot of hardstanding and a couple of sheds with stuff for the car but nothing more technical that a set combination ratchet ring spanner (except the 1/2" which I think some nasty person 'alf-inched).

I do have a Draper torque bar which I (roughly) checked one calibration point on once but I can't read my own signature for that).

Also, very unusually I put a typo in my last post (well one I spotted anyway) -

I [have just recently] had fitted NOS original 'face-adjusted' bearing sets yet the first spacer need to be shortened by 8 thou, the second I've yet to find out about.

Nigel Atkins

Not my sheds, but after a 6 thou shave -

(the rust is mine and on removing this hub I (re)discovered two wheel studs were longer/shorter)



Nigel Atkins

Glad to see it’s a quality DTI.
Dave O'Neill 2

Quite right David, I had forgotten about the elasticity / compression of steel in the axle stub and spacer. Though within the relatively low torque used on the hub nut I wouldn't have expected that to be very great. But your point is made.

Nigel, I avoided entering the discussion on whether these bearings should be pre-loaded or clearance run as I am a Manuel regarding this. (I know nothing). But gut reaction would leave me thinking zero to slight +ve clearance.

My point was about the hub nut having no impact on this but being important for clamping components to strengthen the stub axle. Unlike contemporary taper bearings such as in triumphs where the hub nut determined the bearing setting.

Despite all this precision my technical method has always just been whop it all together with a bit of grease, and check that it spins freely and that I can't feel too much play at the wheel rim. Always been ok and never yet failed an MOT on fwb's. One can over complicate things like this.
GuyW

Nigel,

‘Are you able please to quote the source for the pre-load?’ Yes, with pleasure, but please excuse the length of the reply!

Can you do the same to support your 2 previous statements please?

‘I've been asked to put up a comment about a mistake you've made.’ ‘The design calls for the exact amount of clearance not pre-load.’


As a bit of background, the Sprite/Midget front suspension came directly from the Austin A35, and the engineering design of the front hub unit, using angular contact bearings, determines that the bearings will be pre-loaded, not have a ‘running clearance’.

There are a number of references to bearing ‘pre-load’ and ‘thrust’ in both the Austin Workshop Manuals for the A35, and Sprite/Midget Workshop Manuals.


From the Austin A30/A35 Workshop Manual -

‘The inner and outer ball bearings are non-adjustable, the amount of pre-load on the bearings being determined by a solid distance piece.’

‘Movement between the wheel and hub as one unit and the swivel axle nut at the centre of the hub indicates wear in the hub bearings’.

‘Tighten the castellated nut to a torque wrench reading of 50 to 55 lbs. ft. (6.913 to 7.604 kg.m.). Line up the nearest slot in the nut with the hole in the swivel pin, insert the split pin and lock the nut.’

'Charge the hub with grease, drift on the hub cap and wipe off any grease that exudes through the little hole at its centre.


The early AH Sprite Manual uses virtually the same words, and from the AH Sprite Workshop Manual - 97H1585C

‘The inner and outer ball bearings are non-adjustable, the amount of thrust on the bearings etc.’

‘Movement between the wheel and hub as one unit and the swivel axle nut at the centre of the hub indicates wear in the hub bearings’.

‘Tighten the castellated nut to a torque wrench reading of 50 to 55 lbs. ft. (6.913 to 7.604 kg.m.). Rock the drum to check that play in the bearings has been taken out, and rotate it to ensure that the hub is correctly preloaded. Line up the nearest slot in the nut with the hole in the swivel pin, insert the split pin and lock the nut.’

'Charge the hub with grease, drift on the hub cap and wipe off any grease that exudes through the little hole at its centre.


The later Sprite/Midget Manuals do not have as much technical detail, but the front hub bearing design is identical.

From the Sprite/Midget Workshop Manual - AKF 4021

'ensure that the inner and outer bearings are drifted on with their sides marked 'THRUST' towards the centre of the hub'

'Torque 25 to 65 lb. ft. (3.4 to 8.9 kg. m.)'

'Pack the bearings and the cavity between them with grease. Surplus grease must be removed after the hub has been fitted, to allow for expansion, and in no circumstances should grease be put into the retaining cap.'


The continued use of the word ‘THRUST’ in the later manuals, and at least originally stamped on the bearing, indicates clearly that the application is one of pre-load, not clearance.

The change to the recommended torque settings is understandable. The earlier instruction to ‘Line up the nearest slot in the nut with the hole in the swivel pin’ could lead to significant over-tightening, so by giving a torque range from 25-65 lb.ft., it should allow the castellated nut to align with the split pin hole within the stated torque range.

The change in greasing instructions is also understandable. The early instructions imply that the hub and cap should be filled with grease, and only the excess that exudes through the ‘little hole’ in the cap should be removed. It would suggest that experience showed that a hub ‘full’ of grease could create enough pressure though heat expansion to force the grease through the oil seal behind the inner bearing. By stating that ‘in no circumstances should grease be put into the retaining cap', there will always be sufficient space for the grease to expand, without causing any problems with sealing.

I hope this clarifies the design of the front hub bearings, and in general terms why there should not be any movement between the hub and stub axle, other than normal rotation of course.

Richard
Richard Wale

Hi Richard,
thanks for your reply, I can't reply properly at the moment but I will come back with the courtesy of hopefully a full reply to you (I'm time constrained at the moment).
Nigel Atkins

Guy,
as you know I'm Manuel's more ignorant brother. I don't want to have anything but the very simplest of work on my car, in fact I don't want any work on my car as you know but I have to deal with what I have.

If I'd had the car for decades and a lot nearer its original build perhaps I too would have the simplest of jobs changing wheel bearings. A mate of mine like you can't understand how it's not just take the hub off replace the bearings and put the hub back on.

This is the third time in 12 years of ownership that the wheel bearing have been replaced, the last time was with the Meditech sets so I hoped that'd be it for 40 years but as often happens with my car, parts and garages it wasn't.

Last time and this time I followed all the instructions from Norm's article - and that's where a new world of joy was opened to me.

You may not of noticed but, unusually for me, I didn't join in hardly at all in the long and very long fwb threads as it was all way beyond me, I'm trying now but it still remains something I can't grasp and given all the debate on the subject I might not be alone in this.

Now I wonder how long the current NOS original bearings and shortened spacers will last - upside is that the lovely feel of the steering is back, I didn't notice it had diminished until it was fully back and the front wheels are so quiet I can hear all the other noises including that forgotten undiscovered slight rattle behind the dash.

I honestly don't look for or want the extra 'interest' of these issues but I do want the car running and performing well (and much well above the average classic car but with all the times my car is static through problems it gets harder to keep the average up).
Nigel Atkins

My problems with continuing this subject are -
. (I'm not that clever and don't fully know or understand the subject of bearings) - I no longer possess the limited cerebral skills I once had and I don’t have the necessary education or training in the subject – just some past and recent experience.

. (mixed terminology even in the manuals) - I feel perhaps that the term pre-load might have been used as a general mechanic’s term rather than as a strict engineering term but there’s no way of proving that.

. I'm trying to put up information in good faith and in good spirit to help others, if I wanted to be totally selfish I could just accept that I’ve (hopefully) finally got my FWBs sorted (hopefully beyond the life of the car and me) and having done both sides three times now in my 12 years of ownership.


Richard,
‘The design calls for the exact amount of clearance not pre-load’ – this is the clearance of the face-adjusted (20-degree angular contact ball) bearings.

A typo no doubt but it looks like the change to face-adjusted bearings and solid spacer was with the Austin A30 rather than A35, the former bearings were not face adjusted and the spacer was a “collapsible spring type distance piece”.

The wording in the Austin Service Journal and quotes you’ve put up from the Austin A30/A35 Workshop Manual aren’t always as clear as they could be, more reminders than instruction.

The thrust as I understand it is between the inner and outer races of the bearing.

I agree there should not be any movement between the hub and stub axle with the correct bearings and spacer of the same length as the spacer in the hub.

I think it would be boring for most viewers to re-post and repeat the salient details and explanations from previous threads – but I’m happy to put them up here or provide them to anyone wants them (or they can go through the very long threads in the Archives for themselves).

Cheers.
Nigel Atkins

I'm reading this thread with interest as its already my 2nd time dealing with these bearings. My first set have play in them after a summer of use.

So if you want to post the details, you will have at least one reader.
C MADGE

Chris they are supposed to have some play, the big question is how much play? This is why when we all used to have annual MOTs we shopped around to find garages with 'old hands' who understood that a little play is necessary and doesn't mean an automatic Fail.
David Smith

Thanks David - how much play though ?

My drivers side has no perceptible play if you try and rock the wheel in any direction.

Near side there is some play, not much, but its there. I havent measured it, but it feels like 0.5 to 1mm at the outer edge of the tyre.
C MADGE

1mm at the outer edge of the tyre sounds absolutely fine to me. What do others think?
David Smith

If that's all it is then don't worry!
Bob Beaumont

Up to around 3/16" at the wheel edge is still acceptable, though a new style MOT mechanic used only to moderns might think otherwise!
GuyW

Richard,
if you've not already seen it, you might find the contents of the following link of general interest, and pages 3 and 4 relate to the original fwbs. -

http://www.acmefluid.com.au/larry/austinservicejournal.pdf


Nigel Atkins

DaveO,
Mitutoyo didn't sound like an expensive name to me but I have no idea, where you being sarcastic (which you I'm not adverse to, but some are).
Nigel Atkins

Nigel,

Mitutoyo are a highly respected Japanese manufacturer of precision measuring tools. I have a number of their tools and rate them. I remember when doing machining training in Wichita Ks in the early 1980s the older instructors looked down on Mitutoyo but the younger guys accepted they were as good as what the older guys considered the standards such as Starrett, Fowler, and Moore & Wright, these were guys that worked with these tools during the day and they had to be checked yearly for calibration and Mitutoyo matched the standards.
David Billington

Chris, are you absolutely certain the play is not in the kingpins?
Bill Bretherton

Nigel

No, not sarcasm.

Here’s some of my calibration kit, gently warming in the kitchen, prior to a visit to RR last week.


Dave O'Neill 2

Up to 3/16??? Really, that seems a lot.

Bill all the suspension was new last year so I hope not.
C MADGE

Sorry Dave and David, I wasn't sure as I had a quick look on t'web and thought the dial seemed a very reasonable price and not knowing better wondered if it was a very low price for such an instrument.

As the "shop" does work on old Jag and Aston engines I thought there'd be some degree of checking but have no idea of the tolerances allowed or achieved on those old type of engines.
Nigel Atkins

"... I had a quick look on t'web and thought the dial seemed a very reasonable price..."

I suppose it depends where you looked. There are some fakes around - certainly digital callipers, anyway.
Dave O'Neill 2

Dave,
it was the quickest of looks just out of idle curiosity, £32 looked reasonable to me as a general figure, not saying it's the same gauge, it could be pin sized for all I know. -
https://www.zoro.co.uk/shop/measuring-and-test-equipment/dial-test-indicators---plunger-type/2046s-standard-continuous-dial-indicator-10mm-(1mm)/ps/ZT1017183X?utm_campaign=pla-Measuring+%26+Test+Equipment+-+&utm_source=google&utm_medium=shopping-pla&utm_keyword=ZT1017183X&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=wtqixilaqr&istBid=tztt&mkwid=SEynNipM-dc&pcrid=314501971585&pkw=&pmt=&prodid=ZT1017183X&slid=&pgrid={groupid}&ptaid=pla-393549622960&gclid=EAIaIQobChMI5PqsxZTN4QIVYSjTCh3Auwb9EAQYAiABEgJAQPD_BwE

Wow that's some link length (needs cut & pasting too).

So what do you use all those boxes for then Dave?
Nigel Atkins

To give my results/findings to this thread.

Firstly I want to thank Bob Beaumont and Richard Boobier for their help, thank you, and Lawrence Slater (formerly of this parish) for his great help, advice and detailed explanations that finally (mostly) sunk into my feeble brain, thank you.

And to my mate who is unknown here but is a very long-standing true MG enthusiast (but never suffered as much as me (why?).

I can only say what I found (and believe).

With NOS original bearing sets of face adjusted, 20-degree angular contact ball bearings, the inner bearing with a 2mm radiused inside edge of its inner race to clear the fillet at the base of the stub axle spindle, and spacers adjusted to match the spacer of the hubs - all worked out very well.

If you have the correct bearing sets with original hubs with original spacers or spacers adjusted to match the hubs then you should have very long lasting fwbs (well I hope at least).
Nigel Atkins

Correction - sorry - should have been -

With NOS original bearing sets of face adjusted, 20-degree angular contact ball bearings with the inner bearing - [ having a minimum 2mm depth of radius ] - on the inside edge of its inner race to clear the fillet at the base of the stub axle spindle, and spacers adjusted to match the spacer of the hubs ...
Nigel Atkins

This thread was discussed between 17/03/2019 and 15/04/2019

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