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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Bearing codes

This is a question for engineers.

How does one interpret the number codes on bearings. Specifically ball bearings.

I have two that appear to be identical. One is marked as 3LJ1G and the other 2LJ1G. There are other numbers on both 47 and 97 on the outer race of the first of those and the same, 47 and 97 plus 1L on the inner race of the other.

What does it all mean ?
GuyW

Guy

Google SKF or someone similar?
Oggers

Ooh, there was another post here, but it’s disappeared! Grey?
Dave O'Neill 2

Oggers, they are R & M bearings.
GuyW

You need to know the manufacturer of the bearing to decode the numbers. There is some agreement between different manufacturers systems, but not much - mainly on metric bore sizes.
Each will have their own coding system which describes the type, material, load rating, contact angle, manufacturing tolerance, sealing arrangement, load plane and a squillion other variables so you need the code standard for the make of bearing you're looking at to make any sense of it.
Even the equivalency tables don't always help because some makers concentrate on certain types at the expense of others. For example NSK seem to offer more variation in imperial size radial bearings than most but SKF appear to give more options in axial bearings (thrust races). But that's just a generalisation and may have changed since I had anything to do with specifying bearings.

Unhelpfully, some don't even mark them with the manufacturers name. That can mean a long trawl through equivalency tables.

Edit: yes Dave I was there, but realised what I posted was so generalised that it was unhelpful - even misleading, so I deleted it. Not that the above is any more helpful really :-(
Greybeard

Thanks Grey. Rather more complex than I had appreciated!

Background is I have a rib case gearbox that I am pretty sure is an ex 1098 Morris Minor box.
I do have a table of part numbers for the various A series gearbox internal parts. I cannot remember where I got it but believe it was via someone on the BBS, but some years ago.

I am trying to match the actual part numbers on various components in my gearbox. However there appear to be at least some anomolies in the data on the table so I am not sure what codes can be relied upon.

The two bearings I listed earlier are for the main input and the output shafts. Moss lists these two with the same number, 2A3245 which doesn't match this table. The ones I have look the same, but they have different numbers again, and one of these also differs from those on the table.



GuyW

Yup. What is even more unhelpful is that very often the number is a supplier's stock number and has nothing to do with the bearing spec code. I think that is what's happening in the table you show.
:-(
Greybeard

The originator of that table has confused the issue somewhat by quoting OEM bearing supplier's part numbers for those 2 bearings rather than the BMC part numbers.
The BL parts book gives 2A3245 for the input shaft and 22A465 for the mainshaft, which suggests they are different in some way. They may well be dimensionally the same(45mm ID and 97mm OD) but as Grey has explained there are plenty of other ways they can be different.
David Smith

The first and third motion shaft bearings are similar, but not the same. The inner race on one of them - I can’t remember which - is slightly longer on one side. You can use two of the ‘normal’ bearings if you add a shim/spacer to make up the difference.

I bought some bearings from Hardy Engineering and they supplied a spacer with them.
Dave O'Neill 2

Guy,
as well as the knowledgeable people here I've a vague recollection that David Billington(?) posted something about bearing numbers before but sorry it's not my lucky night with the Archives or thinking of other words to use in the searches.

Perhaps if you say his name three times David might appear.
Nigel Atkins

I saw this thread earlier but didn't feel I had anything to contribute and still don't. As I understand it metric bearings have a standard designation for the OD and ID and that may dictate the width, seal details circlip etc are at the makers discression, inch bearings I haven't a clue although the bearings in the spridgets were metric. As an aside a mate that was interested in old British engineering noted that a Scammel gearbox designed in the 1930's had metric bearings and he tracked the designer down, still alive, and the designer said the reason for the metric bearings was that they were cheaper as rolling element bearings were largely developed by the Swedes IIRC to metric dimensions and so metric dimensioned bearing were always cheaper.
David Billington

I take it back, you only need say David's name twice. :)

Thanks for posting David.

I remember being surprised that there's some metric in the engines of our cars - but I'm on thread drift again, good night.
Nigel Atkins

Nigel, you may well be thinking of me as I have posted on more than one occasion about bearing designations having worked in the industry until the mid eighties.

Guy, I will also be unhelpful in answering your question but will enlighten you as to meanings. They are both specials as the standard bearing is LJ1. LJ stands for light journal and one is the diameter. BMC would have asked for two specials for this application. The first one would be prefixed 2 and the second one 3 and so on if anyone asked for another variation. These prefixes only identify which special it is and give no clue as to what is different. The only way to see what has changed is to compare the two drawings to the standard one.

The changes can be very small such as different radius somewhere, or a chamfer instead of radius or anything else. The width as Dave pointed out will undoubtly be the change for one of them. You may remember that this has come up before with front wheel bearings, as the changes for that were larger radius on the inner race and face adjusted. This is why some comparison tables are wrong as someone has just measured the main dimensions and has not been aware that they are specials.

As I said no help to you I know but hopefully makes the designations a bit clearer.

Trev
T Mason

They do, of course, both have a groove in the outer race for the locating ring. I don’t know if that would have been a standard bearing feature, or a special.
Dave O'Neill 2

Thanks for the information so far. Piecing it together I am getting a better idea of the "Unknown unknowns" as well as the "Known unknowns".

I am just assessing this ribcase gearbox before deciding on a Cunning Plan. It looks in good condition but the layshaft has wear marks and some bearings would need replacing. The current task is to identify the bearings and then tabulate the cost of replacements needed.

What prompted the original question was to see if the codes on the bearings might be sufficient to source them from a bearing supplier at lower cost than going to Moss or other classic car parts suppliers. I wouldn't do so for a cheaper quality bearing but have previously found the same or better quality bearings at Simply Bearings at very much lower prices. Well below half the price.

This only works if one can properly identify the bearing used. The table appears to have too many discrepancies to be reliable and so far searches on the bearing suppliers' webstes don't recognise the codes I have tried.

I know, I should just buy from a specialist like Hardys or Heathrow Transmissions. But I like to learn something in the process and I am not ready to order parts just yet. I may yet decide on a different box.
GuyW

Guy

The original mainshaft bearing is no longer available. You have to use the input shaft bearing with a spacer. I have a new mainshaft/ input shaft bearing purchased from Peter May. I'll have a look tonight to identify the bearing number. The bearings are the same regardless of it being a ribcase or smoothcase.
The layshaft assembly is the weakest part of the A series gearbox so I generally replace with new regardless.
Bob Beaumont

The laygear itself looks fine. The shaft is slightly worn and I would replace it together with its needle roller bearings.
The table shows all gearboxes using the same 2LJ1G for the input shaft throughout the range, but shows a change from 2LJ1G to 3LJ1G for the MK 3 Sprite onwards for the mainshaft. My box has the same combination which doesn't fit with the data in that table. Either the data is wrong regarding the mainshaft bearing, or it was changed for later Moggies as with the later Sprites, and this is a later type box.

Is there an upgrade or adaptation available for the input shaft to front cover oil control? Steel shaft running in an alloy spiral seems to be begging for a better seal!
GuyW

Heathrow transmissions do a modified cover with an oil seal. Its about £50 from memory. The scroll does work in my experience providing all the bearings (including the spigot bearing )are in good condition.

The bearing change may coincide with the introduction of the Ribcase as the bearing carrier is different.
Bob Beaumont

Dave, the groove would not have been on a standard bearing. The suffix G denotes the groove. Suffixes tend to be used for such things (for example some Ford clutch bearings I think it was had a circlip groove on the OD suffixed K) and seals are suffixed S for one steel seal, SS for two, RS for one rubber and 2RS for two.

Guy a good bearing supplier should be able to sort you out but increasingly old blokes with the knowledge are fast disappearing and younger people dont have this knowledge which is what causes the problems.

Many people have asked over the years why everything was not standardised as it tends to be now but back then if you wanted something different you just asked and as companies such as BMC ordered huge amounts on a monthly basis we would supply anything they wanted.

Trev
T Mason

(going back a little now)
Sorry Trev, I did put a question mark against David's name, I done well to remember anything about bearings given the aversion therapy from a certain very long thread. :)

And apologies to David for the mix up, I think you're both used to my muddled thinking by now.
Nigel Atkins

Nigel: I can imagine the fear that Trev quoting " a small radius somewhere" caused.
Graeme Williams

Graeme,
luckily I didn't see that or know what you mean but please don't explain as the mere thought of anything to do with FWB will retard the progress I made with the therapist.
Nigel Atkins

Having looked properly I do now see the difference between the 2TLJ1G and 3TLJ1G bearings that I have. The external race is the same, but on the #3 one the centre rave is longer on the axis and protrudes proud of the outer race on both faces.

So I understand that the 2 and the 3 refer to different "specials" ordered by BMC. And the G on the end probably refers to the snap ring groove on each.

Measuring them, it is apparent they are imperial sizes, not metric as was suggested earlier (?)

I don't understand how the 47 and 97 convert to sizes. Maybe they are just codes? Both are obviously 1" internal diameter and 2"1/4" external diameter. One is 5/8" along its axis and the other protrudes by 3/64" either side, making it 23/64" overall. I tried measuring in decimal metric but the numbers just don't make any logical units.

Moss shows the same mainshaft bearing on all versions of the gearbox and this is different from the input shaft bearing. Whether the mainsaht bearing is actually the same one but supplied with a spacer to be used on the later boxes or discarded on the earlier ones isn't seled out. A pair of these cost £25.70, Layshaft £19.00 and needle rollers to go with it are £8.50. With shims, thrust washers and gaskets that would bring it up to around £75 for a pretty basic refreshment.
GuyW

Guy

The layshaft's quality does vary quite a bit.Some have poor case hardening and you can scratch the ground surface whereas with the original ones that was not possible. Worth checking when it arrives Peter May does a heavy duty one. Its an improvement on the original as it does not have holes drilled in the centre and is much stronger. Its properly hardened but costs about £40!

I rechecked and made an error, the input bearing is different from the mainshaft bearing but its the same for all gearboxes. The mainshaft bearing changed with the introduction of the ribcase. They all use the same bearing now but the ribcase ones need the additional spacer.
The other key bearing is the needle roller on the end of the output shaft that runs in the input shaft. On the smoothcase its a plain bush.
Bob Beaumont

Guy that range of bearings are indeed imperial sizes. Perhaps I should have made that clear before. As you say the bore is 1 inch hence LJ1 as I said earlier.

Trev
T Mason

My mistake on thinking the numbers were size in mm. This is the case for some midget bearings from other suppliers, but again evidently not a standardised rule.
David Smith

Not that it matters as anyone else would do their own measurements if needed, but a mistake there.
I said the centre race on the mainshaft bearing "protrudes by 3/64" either side, making it 23/64" overall". Shoud be 23/32nd overall.

Can anyone say what the "machining" is that is needed to put the ribcase internals into a smoothcase box? If it is just relieving a bit of the alloy housing to provide clearance somewhere I can cope with that sort of thing with a Dremel. But if it is more technical like precision grinding of a bearing housing then that would be beyond my capabilities and equipment.
GuyW

David, for some of the ranges the numbers are indeed metric. However as with most things this does not always apply, a good example being the 6000 range which is metric but not directly relevent to the size.

Trev
T Mason

Hi guy

The SKF bearing number for the mainshaft is LJ1 N (as Trev has said)stamped on the box. On the bearing itself its RL88 N (I think) I got it from Peter May for £21 plus VAT.

As regards the conversion, I do know the rear main bearing carrier is different. There may be some relieving to do to get it to fit. I also know the ribcase carrier has a dowel which locates in the rear casing. I don't think the smoothcase has the dowel. I can't quite see the purpose of this other than to stop the carrier rotating in the main housing.

The ribcase main and input shaft when assembled are slightly longer than the smoothcase. I think the input shaft is longer.
Bob Beaumont

As the 'originator' of the gearbox part numbers table, I have re-checked the 3 ball bearing part numbers against the relevant BMC 'Service Parts List', and updated the table - see attached.

The attempt to use the actual bearing part number was on the first 2 versions of the table only, after that I reverted to the BMC part numbers - now on v6! Apologies for the confusion.

The latest information I have shows:

948 smoothcase gearboxes have the same part number (2A3245) listed for both the input (1st motion) shaft and the rear mainshaft (3rd motion).

1098/1275 ribcase gearboxes have the same input shaft bearing (2A3245), but a different part number for the rear mainshaft bearing (22A465).

Guy,

The sure way of identifying the gearbox is from the part number stamped on the primary (1st motion) shaft. The table shows the various part number used.

Richard


Richard Wale

Oops - always helps to upload an 'attached' file!


Richard Wale

Thanks Richard

very useful

As an aside I think the smoothcase 1st motion shafts don't always have a part number stamped on them.
Bob Beaumont

Thanks Richard. That now accords with what I have found. I knew my gearbox was a Morris Minor one, both from the ring in the end of the clutch lever arm and the number on the input shaft which also has 19 teeth on the input gear.

The confusion was only that my Mainshaft bearing was different to the input shaft which contradicted your earlier version of the table for that box which listed the second part number.

That said, it is extremely useful and I wasn't grumbling about it! Many thanks for the update.
GuyW

Bob,

Ah, so need to count the teeth or work out the ratios on a smoothcase box?

Guy,

Always good to get better information! Thanks for the query.

Richard
Richard Wale

Another question then for the gearbox experts, about laygear end float.

Both the workshop manual (reprint) and Haynes refer to a change in laygear endfloat of 0.001 to 0.003 on Sprites MK1, 2 and 3 to endfloat of 0.003 to 0.005 on Sprite MK4. What seems odd is that the change doesn't relate to the introduction of the ribcase baulk ring syncro boxes as one might expect, which came in with the 1098 engine (Sprite MK 2 1/2). Is this an error? Should the endfloat change coincide with the smoothcase to ribcase change?
GuyW

Richard
yes That is the only way.

Guy, My Frogeye workshop manual and my Sprite and Midget manual, both original BMC publications, say 0.001 to 0.003. The Sprite and Midget one covers 948cc cars through to 1275cc cars with engine prefix 12V.
I have always built mine to 0.001 to 0.002. Its hard however as finding the correct laygear washers can be a struggle! The ones I bought from M--s do not fit and are too small for the layshaft to go through!
Bob Beaumont

Richard, the different part nos. for the 1098/ 1275 box is because, I think, a spacer is included with the rear bearing.

Bob, I fitted Moss thrust washers with new layshaft. Maybe my layshaft is slightly smaller diameter (it's from Moss).
Bill Bretherton

Bill

The original 1098/1275 bearing had a larger width centre. Its no longer manufactured so the replacement bearing has a spacer to make up the difference.
The layshaft are all the same diameter otherwise the needle rollers in the lay gear will not fit. Sounds like your batch of washers were ok. More sloppy quality control from suppliers
Bob Beaumont

"The layshaft are all the same diameter otherwise the needle rollers in the lay gear will not fit"

Also, the layshaft wouldn't fit the casing.
Dave O'Neill 2

I think Bill was joking,- just being ironic about parts quality!

I am still puzzled about this apparent change in end float for the largest not matching with the introduction of the ribcase. It is quoted in my factory manual reprint and in Haynes. I guess it must relate to the 22G1100 laygear, rather than the casing.

I have ordered shims to get me a 1.5 thou clearance.
GuyW

I seem to remember the end float being awkward to measure (with feeler gauge) and I had a couple of shims to choose between which I exchanged a time or two until happy. You have to let the laygear drop into the box on reassembly in order to install mainshaft (and input shaft I think) so I put something like a length of insulated cable through it, together with the shims, then the cable was carefully removed and the layshaft inserted from the outside.
Bill Bretherton

Update as this may proove relevant to some.

Having started out hoping to find a better price buying from bearing specialist, I found that at the present both Moss and Sussex Classic Cars are very competative with their current prices. So I bought from Sussex as I wanted other stuff from them as well. The bearings supplied are both the same but include shims to use as spacers to make up to the 22A465 bearing dimension. It is actually packaged with a Moss instruction sheet. All as expected.

The bearing type is a LJ1NR so out of interest I searched bearing suppliers. Several suppliers list them as NLA; Simply Bearings are 2X Moss' s price and Hendersons list them with a note "limited stock, no longer in production."

So if you are likely to need some, now might be a good time to buy in some spares.

Advice: Is there a proper way of getting the gear cluster springs and ball bearings inserted without them disappearing into the stratosphere? I don't appear to have enough fingers!

I suceeded eventually with a zip tie around the 3 balls and gradually tightening it which did work OK but with the ever iminent threat of loosing my balls!

GuyW

Guy

There was a Churchill special tool for getting the springs and balls in, only ever seen one though. I like you use a wide zip tie.
Bob Beaumont

Perhaps I should have posted a photo of a zip tie on the
Tool Makes special tool identification quiz. Easy to identify it - but what is it used for? !!
GuyW

I have managed it with many fingers. It would probably be best to assemble inside a large bucket, or similar container, to minimise the risk of loss. Disassembly can be done inside a plastic bag.

A substitute for the BMC tool is a baked bean can - or some other tin of the correct size - with a single hole drilled in the side. Insert a spring and ball through the hole and rotate the tool to the next position, repeat and rotate, then repeat again. With all three springs and balls inserted slide the outer synchro hub into position, displacing the ‘tool’ at the same time.
Dave O'Neill 2

The zip tie actually worked quite well. The tie itself wouldn't pull the balls in against the spring tension, but it held them in place. I then went round each in turn pressing the ball in against the spring with a small screwdriver and tightening the zip tie a notch or two for each one. Once all 3 were far enough in place the outer syncro hub slid over the balls, pushing the zip tie away.
GuyW

I tried Dave's tin can with a hole in it method but couldn't get it to work. The problem is the the balls all need to be depressed well below the tips of the inner synchro ring teeth before the outer will slide over them. Even a close fitting tin can won't achieve that and worse, it screens them from further assistance so it just locks up.

I reverted to the zip tie which also only pulls them in flush with the tips of the teeth, but I could then still get at them and slip the ends of 3 small flat blades screwdrivers under the zip tie to get that last bit of ball movement.

Working inside a bucket is very good advice though - a brilliant idea!
GuyW

I agree Guy after a lot of failed ideas, the zip tie was the best. I used some which were about 4mm wide. the extra width retained the balls more easily.
Bob Beaumont

Bob,
like you I found that the centre hole in the new shim washer as supplied for the laygear was a tad undersized and it wouldn't fit onto the layshaft. I had to open it out slightly with my Dremel. Glad I checked before positioning it in the gearbox and fitting all of the rest of the gears in !
GuyW

I also used 3 smallish flat blade screwdrivers to get the balls in, tied on, I think, with a strand of insulated mains cable but the zip tie sounds better. I did it in a washing up bowl. It's still quite challenging and it's easy to get the outer sleeve/ cog in the wrong place (btdt.....).

Maybe my shims were too small as well - I forget, it was 3 or 4 years ago.
Bill Bretherton

This is the synchromesh assembly tool from the MGB WSM.

There is a similar tool for the Midget IIRC.


Dave O'Neill 2

I use a piston ring compressor and three small screwdrivers
Dominic Clancy

Thanks Dave. I saw one on an auction site and it went for silly money. Never seen another.
Bob Beaumont

Interesting special tool. I am not sure but it rather looks from that illustration that the inner surface has serrations around its surface. That would explain how the balls press down against the springs that little bit extra needed to get them to slip under the outer syncro hub.

Gearbox all back together now. Feels a little notchy but not seriously so and hopefully it will feel smoother with some oil in it! Time will tell.

Next target is to match this to the engine with correct clutch and backplate combination. Sorry, but I feel another thread brewing!
GuyW

Guy, it does look serrated, but can’t be, as it has to rotate.
Dave O'Neill 2

Yes I realist that, but if reasonably precisely machined it could be made so that the serrations were sufficiently fine that they cupped the ball bearing directly over the spring and held it aligned. Then a sharp tap on the outer hub would click it into place. If you did that with an unserrated tool the impact would just displace the ball bearing.
GuyW

Was it the ribcase or the smoothcase you rebuilt
Bob Beaumont

The ribcase.
The plan was to dismantle the ribcase first, partly as a training excercise but also to assess what sort of condition it was in. Then take a look at the smoothcase.

The ribcase was actually better than I had thought from my early squinting through the side cover. I may still dismantle the smoothcase to assess that one as well. But I plan on taking a break from gearboxes for a while.
GuyW

If you are fitting the ribcase to your 1098cc engine then it should need very little fettling. The 1098 has the thicker backplate and flywheel drilled for the larger diameter clutch. The clutch slave is the same for both the 948 and 1098.
Bob Beaumont

That certainly makes it much easier. If I were using the smoothcase I would need to swap over and fit the backplate off the old 948 engine that I have, awaiting restoration. The smoothcase box has a shorter input shaft that wouldn't suit the thicker plate steel backplate.

The bell housing on the smoothcase also looks slimmer and maybe wouldn't clear the larger clutch anyway?
GuyW

Indeed that's right. The smoothcase may need relieving slightly. The other change is to use the 948 starter motor with pressed steel backplate. It has a slightly thicker mounting flange. otherwise the end of the starter motor shaft hits the dome cover of the starter motor housing on the gearbox.( or remove the cover!)
Bob Beaumont

Still toying with the idea of fitting the ribcase internals into the smoothcase.

"the rear main bearing carrier is different. There may be some relieving to do to get it to fit. I also know the ribcase carrier has a dowel which locates in the rear casing. I don't think the smoothcase has the dowel. I can't quite see the purpose of this other than to stop the carrier rotating in the main housing."(BB)

One could either just leave the dowel out, or drill a matching locating hole in the smoothcase rear extension. Although he carrier is a tight fit the logic may be as a precaution against the bearing carrier rotating which could cause the cutaway for the reverse gear to clash with the gear wheel.

"The ribcase main and input shaft when assembled are slightly longer than the smoothcase. I think the input shaft is longer."(BB)

Yes the input shaft is longer on the ribcase. Is that the only reason for the greater overall length? Or from another aspect, are the laygears of both gearbox types the same length?
GuyW

Shall I shan't I?

It looks a fairly simple task to modify the front cover to take a standard single lip oil seal. It would involve enlarging the present 1" hole in the cover out to probably around 2", destroying the scroll in the process. Then press fitting an oil seal, maybe using an adhesive for good easure.

The seal would then run on the machined surface of the input shaft. On mine this measures at 0.998" so I would need to source a seal to match that. But there are plenty of size variations available for £5 or less.

Would the hole need to have a lip to it for the seal to fit against The alloy cover isn't thick so this might be a problem but as there s no axial thrust I think a close fit plus adhesive would do it. The challenge for me would be getting the hole accurately concentric to the shaft.

Or I could just spend £100 or so for a new type oil seal cover.

Dare I?
GuyW

Seeing as it isnt my car or money, I say yes go for it. What could possibly go wrong.........?

Infact I double dare you :D
C MADGE

Away from the "shed" (AKA home) for a few days now, so plenty of time to get cold feet!
GuyW

The laygear is the same length (same layshaft)I thinkhe input shaft is longer due to the thicker steel engine backplate on the 1098/1275. I assume the thicker backplate improves rigidity.
Bob Beaumont

I've wondered about attempting to machine the front cover plate to take an oil seal but would worry about accurracy.
Bill Bretherton

I thought the Peter May version was expensive but on checking l see his is actually a new purpose made casting so for a quality part, the price is probably reasonable.

Then there is an eBay offering at £50 which looks like what l was envisaging. Just the centre hole opened out and a seal fitted/glued in position. Given the low cost of seals this is probably proportionally a less good deal with the possibility of a DIY version for 1/10th of the price.
GuyW

I would worry the seal coming loose and creating a fairly major leak. I think the scroll is fine providing the bearings (including spigot) are ok.
Bob Beaumont

On my race car, I had the hole enlarged on a lathe - no lip - and a seal fitted. Worked fine.
Dave O'Neill 2

This thread was discussed between 03/09/2018 and 14/09/2018

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.