It now appears the lipped roller bearing used on the timing side of M20/21/33 and B31/33 motors has become obsolete....(MRJA7/8)

They are still available manufactured made by Chinese and Indian bearing companies but not it appears, from a 'branded' European or Japanese manufacturer....(note that 'Sterling Bearings' are Indian)...

Does anyone know of a source of these from a branded manufacturer...One that you definitely know currently has them in stock?....Ian

email (option): ian@wright52.plus.com

Ian,

I have been on a wild goose chase since April this year trying to find a branded bearing MRJA7/8 or equivalent numbers. So far I haven't found anything but old stock and very expensive at that. There are quite a few online shops which still list this bearing but when you order (and pay) they will tell you that it is not and give you a refund. I have been disappointed quite a few times by now.

The non-lipped version is still available. Could that be a substitute or is the lip essential?

Regards,
Leon

email (option): leonhop3@planet.nl

Hi Leon...Thanks for the info...Pretty much as I have found it...
The non lipped version will work as long as the inner cannot move on the shaft (so is a tight fit or firmly loctited in position)..
If not it can move through the unlipped outer and start to wear the crankcase...
Also the unlipped version is difficult to remove from the crankcase once fitted...

The reason for my query is that I need one or two bearings fairly soon but only have one at he moment..
In the longer term I have invested some money in having a small batch of these bearings manufactured by a European company (in the C3 fit)..
However, these will not be completed until December/January....Ian

email (option): ian@wright52.plus.com

Last one i bought was this Ransome & Marles one:



I know you are looking for a current UK producer but did you see this new old stock one on eBay currently...
http://pages.ebay.com/motors/link/?nav=item.view&id=370783286387

Ian
I can still get NKE MRJA7/8 made in Austria bearings here is Oz, it wasn't cheap from memory.
I can get a price for you if that helps you
Cheers Darren

email (option): Darrenacartwright@yahoo.com.au

Thanks Fred/Darren...Yes, I'd be interested in a price per bearing for those Darren....Ian

email (option): ian@wright52.plus.com

Hi Ian, the C3 is the catch as you know. The bearing firm I use offered to "resize" NSK's to C3 at about £100 each otherwise QCB's from China in C3. I would like to know if the fitted clearance denoted by C3 is critical if used in "worn" bearing housings.

Cheers Pat

The Chinese have made machinery for decades now, have they not used bearings in theirs? One day you'll all be reliant on them as western producers fade away!Someone will have to be a guinea pig and bite the bullet!

Hi Ian,

I mailed you about a week ago regarding the bearings...

I found an existing NOS of them, British made,
But it will be about 65 Pounds each..

Very expensive, but there should be about 10 of them, I have been told,
Probably not C3.

If you want, please mail me. I can buy and send at cost.

Noam.

email (option): noam10@gmail.com

Noam..I've mailed you...

Douglas..You may be right..one day we may need to rely on the Chinese, Russians etc. for bearings....but that day isn't here yet...
Both those countries certainly have made machinery for years..but it's unreliable machinery.
I think everyone has a pretty low opinion (well earned) of Russian and Chinese vehicles...
I had a Russian sidecar outfit (new) and I can assure you it was very poor, including the bearings...
Personally I don't think I, or the Chinese, are quite ready to do business with each other...Don't forget there are thousands of unhappy consumers who thought they might try being a 'guinea pig' with the Indians!...
There little point repeating the process with the Chinese or Russians and getting the same result...
I don't mind where a part comes from if it is well made, but the truth is that, currently, the notion of what is an acceptable standard for manufactured goods in those countries and in say Japan or Europe is still very different.....Ian

email (option): ian@wright52.plus.com

Ian
The price is 92 quid, and that was for a steel cage not brass cage.
Cheers Darren

email (option): Darrenacartwright@yahoo.com.au

Hi Darren...Thanks for chasing that up..I'll give them a miss though, as by the time I have added postage and import duties they'll be too dear...Thanks..Ian

email (option): ian@wright52.plus.com

I will check with my local supplier, who is usually very good and the right price. I will post on here anything they come up with.

I had asked R&M for a price yesterday just out of interest, they mailed me today, the price is for exactly the same one i bought before as pictured in my previous post, but they wanted £157.90 (including p&p of £8).... :O
i got mine for £37.43 via Amazon (bearing station) here's the link ..now shows unavailable:
http://www.amazon.co.uk/gp/aw/d/B0030MB5XG
however .. i do remember after paying, bearing boys rang me asking for more time explaining their one had vanished from stores & they needed to outsource it & were going to make nothing on it.
That eBay one currently on offer 370783286387 looks cheap now..

I just bought this one from Les at Russells for £49.50 but it was his very last one. He says he has been quoted over £70 each (to him) to get them made in UK.
Ian you can borrow this one if you need it and replace it with one of yours when they arrive. Ron

email (option): ronpier@talk21.com

Is there an easier to get ball bearing to replace it with?

I think in the M20 it may be feasible to use two RLS7 ball bearings instead of the MRJA7/8 roller and one RLS7....The two balls would have sufficient load capacity for the sidevalve motor, in other words more than the single roller fitted to OHV engines...
The widths of the bearings would need to be checked however and both would have to be a snug but sliding fit on the mainshaft....

For the OHV motors fitting a single RLS7 would be more of a gamble as they only have a single bearing...
Not only do they produce substantially more power than the sidevalve (even in standard 350cc form) but the ball bearing has a significantly reduced load capacity compared to the roller....Ian

email (option): ian@wright52.plus.com

Most unusual to use a roller bearing on the timing side with most british bikes then anyway. Two ballbearings on the timing side is still over engineering anyway. I was always surprised that the overhead had one but the soft powered sidevalves use two?? A most unusual expense for BSA.

Hi Douglas..1936/37 M20s only had a single bearing as in the OHV types...

The 38 redesign that introduced an air gap behind the tappet chest led to the cylinder being widened and the timing side crankcase half being widened to accept it...
The cam followers etc. were also moved outwards to realign everything...
That meant a longer mainshaft on the timing side and the extra bearing was introduced to support that....

Power output didn't change at all and wasn't a factor, it was purely a case of giving physical support to the longer shaft...Ian

email (option): ian@wright52.plus.com

email (option): john.kater@chello.nl

Hi John..I think Douglas was referring to the hypothetical situation where the roller had been replaced by a second ball bearing as substitute for the currently unavailable (in a branded make) roller bearing....Ian

email (option): ian@wright52.plus.com

Anyway chaps, I wouldn't hesitate to use two ball bearings because let's be realistic, the odd 1000 miles wouldn't wear them out anyway!

Hi,i think that this type of one way floating roller bearing (for want of a better description)is to allow the crank to expand as engine temperature increases.
The drive side is all locked up ,so the floating rollers can move sightly
towards the timing side.Darren Wrudd is a bearing man,maybe he can throw some light on this problem.
cheers Rick

email (option): richardholt@rocketmail.com

Rick, that can't be the case because the ball bearing next to it has no facility for movement in that plane & i think the single lip idea was to insure clearance on the rollers sides after assembly.
I'm sure i have read of people using a no lip roller in that position.

The timing side ball bearing and the fixed drive side ball bearing should be a clearance fit on the shafts...

BSA manuals refer to a 'snug fit by hand' in each case and to fit them by hand at all requires a small but significant clearance fit....not an interference fit....

BSA publications also recommend that the shafts are reduced using emery cloth if necessary to achieve this fit from new....
If the ball bearings are too tight a fit it makes for difficult reassembly and makes correct positioning of the crank using the shock absorber assembly more difficult and potentially less certain depending on just how tight they are.....

Further, applying too much force to the crank to drive it through the ball bearings (if they are an over tight fit) runs a real risk of altering the flywheel alignment...

Non lipped rollers are difficult to remove from the crankcase once fitted I have found...Also if the inner bearing is not loctited to the shaft and is too loose it can move through the bearing outer and 'run' on the aluminium of the end of the crankcase bearing housing..Ian

email (option): ian@wright52.plus.com

Hi Ian,

Sorry for the delay- work and so on..
This is what I got for now-

1 NOS bearing.
The seller said that he had 3 units,
(It turned out that the dealer who said he had 10 units, another dealer
did have it "But if I want it, he has to order from the supplier..")

Anyway, this guy said that he had 3 of them.
When I got to him, one unit was opened on both sides, no shoulder,
The other one looked fishy, opened, unwrapped and dry, so I passed,
and this last one was in a petrified oil paper (original)
which broke when opened. It was lean and oily inside as packed.

It was some 65 Pounds and change.

Please mail me if you want it at cost (I need your address if yes)
And if not- no worries, I can give it back and receive the money.

here are some photos. (The brown colour on the outer race is oil, not rust..)

Cheers,
Noam.

email (option): noam10@gmail.com

Hi Noam...mail on it's way today (Wed)...Ian

email (option): ian@wright52.plus.com

Finally received a response from my local stockist, he was out and could not supply except from India. He put me on to a specialist manufacturer not far away. They came back with a price of £80net for one. If a batch of 10 were ordered then there could be some flexibility in price. If anyone wants to go ahead with combining an order to get up to a batch please let me know.

Duncan

email (option): cruiserchooser@hotmail.co.uk

No way will any of our M20's be indulged with them if there is a 20 dollar ball substitute!

I'll fit the original spec. bearing to my sidevalves if it's available..though there are limits to how much I would want to pay for them. What is 'reasonable' depends on the individual I suppose...
£65-£70 doesn't seem ridiculously expensive to me for a precision bearing...(an hours labour in a typical car garage?)

Regarding OHV motors with a single bearing that produce more power (and a lot more power if tuned) I don't think I would want to try the ball bearing (assuming it will fit) unless I was absolutely forced to as I have my doubts as to whether it would be up to the job in that application...
Ball and roller bearings in compatible sizes have quite different load bearing capabilities, with the ball bearings having the lesser of the two.....

Saying that though, trying it is the only real way to find where the limits lie in a particular application...I'm not ready for that experiment though while I can still get the specified type that I know work OK...Ian

email (option): ian@wright52.plus.com

Hi Duncan,

Since pre war BSA's use this bearing as well I'd be interested in a couple of bearings if we could get the price down to more linke 65 - 70 like Ian stated.

Regards,
Leon

email (option): leonhop3@planet.nl

Hi Leon and Ian

I too share the concern about cost, but it may be that there comes a time when we have to take whatever there is :-( Ok we may not be at that stage yet, but when that stage becomes 'India' then we might be glad we took advantage of available British made offers?

I will sit it out for a week or so and then get back to the manufacturer with a number of 'definites' and see what price they can come up with. It may be that I am a bit cheeky and take the line with them that I will take 'xyz' quantity if they can deliver them at £abc price. The issue of VAT of course should not be forgotten, not being a business I can't avoid this.

email (option): cruiserchooser@hotmail.co.uk

You are right of course...The price I have quoted as 'reasonable' is what I would happily pay...but I would pay some more if I had to...

I have frequently said that old bike enthusiasts live in a 'false' world in many instances, buying NOS ex army parts that were paid for a long time ago by the tax payer...These are now sold at an arbitrarily determined price that bears no relevance to the manufacturing cost today...

You can get a new M20 gearbox mainshaft for £70 for example....You wouldn't even look at manufacturing one today for that...

People wince at paying £100 for a NOS piston...I paid more than that for a Rotax piston over 20 years ago...and a Ducati piston today is the best part of £250....

Even if you look at second hand parts it's often not as bad as it seems...£200 for a M20 petrol tank....It would cost double that, and probably more, to get one of equal quality made today....

We have also regarded all this stuff far too much as an inexhaustible supply...This bearing has become obsolete because there simply isn't enough demand to make its manufacture worthwhile..not surprising really when most of the bikes it could be fitted to do little or no mileage once rebuilt...Like they say... 'Use it or lose it'....

This situation is the future however..More and more parts will become obsolete and if we want them we will have to face the reality of modern, small volume production values....

I've seen the future...and it costs more...Anyone for a one off big end?....Ian

email (option): ian@wright52.plus.com

Hi Ian,

I know that sometimes you have to be "Initialized" trough the forum
in order to read e-mails,
so- I've mailed you..

BR,
Noam.

email (option): noam10@gmail.com

Lots of twins only used a single ball each side? I don't mind if you all waste your money but next rebuild will definetly be getting 2 ball bearings. It's only a slow plonker!

[ 'I think in the M20 it may be feasible to use two RLS7 ball bearings instead of the MRJA7/8 roller and one RLS7....The two balls would have sufficient load capacity for the sidevalve motor, in other words more than the single roller fitted to OHV engines...' ]

Hi Douglas...Note my comment in one of the previous posts....Comparative widths of the two bearings and the fit on the shaft would have to be correct though......Ian

email (option): ian@wright52.plus.com

Hi guys,
Sorry to jump in to the discussion late, but I have just got back from a holiday.

I think Ian is quite correct that the load carrying capacity may be enough on the RLS7. (LJ 7/8) bearing, which dimensionally is the same as the roller, but this is not the issue. Fitting the bearing with a floating inner means that the whole thing goes together much smoother and absolutely no thrust load is applied when assembling as the 'float' allows for that.

I would not like to risk a ball bearing in its place for that reason of thrust loading and with the best will in the world, unless you can guarantee the precise location on the shaft when assembled, neither should you. Too loose a fit and it will spin on the shaft, too tight and position can be wrong ( only a thou or two to pressure the bearing) or you may have to drive it too hard as Ian said.

The bearings are available and £60 is not too serious a price for peace of mind as you make that special trip. But try to avoid the older, dry stored bearings like in the photo above. If you look on the inside of the outer race, it has lines of " grease" where the rollers have sat for the last fifty years in storage. If you look very closely after cleaning away this grease line, a dark grey line remains which is the beginning of pitted corrosion and is not good. You also get the same on the roller where it touches the outer in storage and it all adds to reduced bearing life.

So with my 'bearing Co' head on, Wait for the back ordered C3 bearings and do it right.

Darren

email (option): dwrudd@lineone.net

I'm not about to make this change to the specification as I have previously noted.
However, it seems to me it is entirely workable to use the ball bearings in the SV engines, but ONLY if carefully assembled...
Conditions relating to shaft fit/axial loading during assembly would be no different for the additional ball bearing than they are for the existing one I wouldn't have thought....(or the drive side ball bearing)

Although the bearing is the same width as the roller it is fixed in position by it's fit into the crankcase much as the outer of the roller bearing is..

Therefore the fit and condition of the shaft would be the critical factor and have to conform exactly to the limits specified by BSA for it to be assembled easily and to function correctly....
It has to be said that many cranks are now undersize on the mainshafts and the separate inner and outer of the roller bearing does give the option of Loctiting the inner to the shaft to restore the fit...Not possible with the ball bearing if easy assembly and more importantly, disassembly are going to be retained...

Of course this wouldn't have entered BSAs thinking when all the components were new, within tolerance and Loctite hadn't been invented!!

The use of the roller bearing in the OHV and early sidevalve engines, where it was the only bearing on the timing side, may be explained by its load capacity versus the physical size of the bearing...It isn't particularly big for a main bearing....Possibly ease of assembly was also a factor. Also someone mentioned the ability for it to move under the effects of the longitudinal expansion of the crank as it warms up...

When the outer ball bearing was added to the later sidevalve engines though the reasons for the use of the roller bearing are even less certain...

On the drive side the inner roller bearing and drive side spacer are locked between the inner race of the fixed ball bearing in the crankcase and the cheek of the flywheel.. Here the lip of the roller outer bearing has no function at all as far as I can see...

It does lead to the question of why BSA didn't use ball bearings as some other manufacturers did....or rather, why exactly did they choose the lipped rollers?...Ian

email (option): ian@wright52.plus.com

Deep groove ball bearings are more forgiving with respect to alignment than roller bearings. Crankshafts that have been apart and re-assembled a number of times will have difficulty achieving factory alignment specs and where this is the case, there may be a good case for fitting ball bearings in preference to roller bearings.

email (option): pvlietstra@gmail.com

I am sorry Peter but I disagree. If the bearings are out of line due to poor fit or worn shaft or housings, a deep groove ball bearing would have more chance of very poor service as the thrust imparted on the balls would effectively make it a two point contact due to the twisting force.

A roller bearing would be subject to the same twisting force but as the surface area is much greater, it would tend to hold the true line better and have less overall effect.

I have quite a lot of experience in this field and have dealt with the scenario hundreds of times when engineers have effected poor repairs and left the journals out of line.

There are however ranges of bearings with self aligning features in balls or rollers and whilst many are double row versions which may be a little wider, the id x od are often the same so can often offer a solution. The best solution though, as we all know, is proper engineering repair to the housing and/or shaft.

Darren

email (option): dwrudd@lineone.net

[ 'The best solution though, as we all know, is a proper engineering repair to the housing and/or shaft.' ]...

Absolutely, running with the crankshaft outside of its concentricity limits loads up the main bearings, increases vibration, will increase the wear on the timing gears due to incorrect clearances and makes for a very noisy engine (for the same reason)...

The general rule, and the most sensible course usually, is to treat the cause, not the symptom....Ian

email (option): ian@wright52.plus.com