Portugese layshaft bearing

lazyeye6

lazyeye6

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This is the Portugese layshaft bearing removed from my ‘74 Commando with a build date of 10/73 and replaced with a roller bearing. Without a forensic examinationI I can find absolutely nothing wrong with it. The inside cage is metal. Has there been any analysis done as to what years/serial numbers the faulty bearings were being installed?
 

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lazyeye6 said:
Without a forensic examinationI I can find absolutely nothing wrong with it.
Click to expand...

In which case it hasn't reached the point where the brass cage has started to break up.

lazyeye6 said:
Has there been any analysis done as to what years/serial numbers the faulty bearings were being installed?
Click to expand...

Any of the factory-fitted 6203 ball bearings can potentially fail but the Portuguese 6203 bearing with the folded tab brass cage (as yours has) fitted to later 850 models has the highest rate of failure.
 
Same part was in my 74 engine/frame/gearbox # 313... ( brass cage portuguese L/S bearing)
Bike had done just over 10,000 miles from new.....Boom 💥
Happened at about 50mph in 3rd gear
 
1975 850 mk3. Prior to rebuild, the bearing gave up so dramatically, it needed a replacement gearbox case. I think this was why the bike was taken off the road and parked up for some years.

I wouldn't fancy being on the bike when it happens!
 
lazyeye6 said:
This is the Portugese layshaft bearing removed from my ‘74 Commando with a build date of 10/73 and replaced with a roller bearing. Without a forensic examinationI I can find absolutely nothing wrong with it. The inside cage is metal. Has there been any analysis done as to what years/serial numbers the faulty bearings were being installed?
Click to expand...
How many miles on the Norton, usually they blow around 10k to 15k miles mine blew at 12k miles from new but if your hasn't fail with a lot more miles then you have just been lucky.
I can't believe how many 50 year old Nortons are still around with so little miles on the clock.
Anyway you pulled the bearing out and I say you have replaced it so you been lucky, I was lucky mine blew when I put it in gear when I went to leave home with a sight bang then nothing, pull the 2 gear covers off to find all the balls at the bottom on my GB and no other damage and yes it did make a bang noise when I put it gear and went to ride off.

Ashley
 
I keep wondering how many schillings Norton saved by going to this bearing, and the year they did so.
My '62 build Atlas has over 85K miles, and no evidence (kick lever droop) of imminent failure of the bearing.
I also keep wondering how much longer it will last, but I have a Mick Hemmings bearing in stock and first evidence of failure, the gearbox comes out for a rebuild.

Slick
 
All the 6206 bearings in my old spares box are RHP . Never had to change one on my Domi 500 racer, 750 racer nor my road '68 Commando.
 
It only seems to be the later 850s that had problems with the Portugese bearings, what make bearings they ran in the earlier gear boxes as they seem to had no problem.
Norton at the time didn't have any reason to know about these failed bearings and by the time they did they were goneeee, so between 73 to 75 they used different country made bearings.
And take into count some of these failed bearings didn't show up for a few years of ownership and the factory was closed down.
But I can't believe how many Commando's are around to this day with less than 10k mile on the clock, yes my layshaft bearing failed in 78, 2 years after buying my 850 new and to this day am still running with the replacement bearing with over 160k miles on my stock GB with a 4 kick start pawls and a broken kick start shaft and worn kick start gear in that time since and it's been over 25 years since I been inside my GB when I replaced the KS gear that was wearing the KS pawl.
The only time I change my GB oil is when I go inside it, I use Hypoid gear oil at the recommended weight in the Norton bible at the right measurement level.

Ashley
 
My P.P.O.S. (don't make me spell it out!) layshaft bearing looked fine upon removal at around 9 or 10k miles on the clock of my '74 850 mk2. Followed the Hemmings DVD and used his recommended phenolic cage ball bearing. Put another 14k on clock, all fine.
 
Tornado said:
My P.P.O.S. (don't make me spell it out!) layshaft bearing looked fine upon removal at around 9 or 10k miles on the clock of my '74 850 mk2. Followed the Hemmings DVD and used his recommended phenolic cage ball bearing. Put another 14k on clock, all fine.
Click to expand...
I did exactly the same. Have used the 6203TB bearing in all my rebuilds since. I originally replaced the standard bearing with a 'superblend' roller, but the loss of positive layshaft location was a problem.
I'm sure the original 6203 - Portuguese or otherwise - was great in the Matchless G3, but was simply not designed to manage the shaft flex encountered on the 850, especially the 'A' models and Mk 3 with a higher second gear and 22T gearbox sprocket.
 
ashman said:
It only seems to be the later 850s that had problems with the Portugese bearings,
Click to expand...

Yes, because only the later 850s had the Portuguese layshaft bearing (so unlikely to be found in a Matchless, Dominator, etc. 'box) but the pre-Portuguese layshaft bearings can still fail and presumably why AN only lists the 06.7710 roller bearing for all AMC/Commando and laydown gearboxes.
andover-norton.co.uk

Andover Norton Spare Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Genuine Andover Norton Parts created from the original drawings.
andover-norton.co.uk
andover-norton.co.uk

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.
andover-norton.co.uk

Layshaft bearing failure

I have read many posts related to the failure of the gearbox inner layshaft bearing and what I still don't know is whether the failures are more common in the later model Commandos. Mine is a mid-year 1970 and I don't have any way to know whether the PO changed the bearing or not and the bike...
www.accessnorton.com www.accessnorton.com
 
Last edited:
texasSlick said:
I also keep wondering how much longer it will last, but I have a Mick Hemmings bearing in stock and first evidence of failure, the gearbox comes out for a rebuild.
Click to expand...
If you are lucky then the tapping of the kickstarter lever on the back of the leg will be the warning, but it can also not show until the back wheel is locked up so if you actually have the MH bearing then change it this winter.
 
kommando said:
If you are lucky then the tapping of the kickstarter lever on the back of the leg will be the warning, but it can also not show until the back wheel is locked up so if you actually have the MH bearing then change it this winter.
Click to expand...
I got no warning....she just locked up hard...and I slid to to side of the road...with a twitching sphincter 🙂

With the chain link spotted i got the chain off the rear sprocket..so I could push her to the next closest house (country back road)...and ring a mate for a trailer ride home....managed to get the case welded and machined up by a experienced local fabricator...still sweet as today...
 
B+Bogus said:
I did exactly the same. Have used the 6203TB bearing in all my rebuilds since. I originally replaced the standard bearing with a 'superblend' roller, but the loss of positive layshaft location was a problem.
I'm sure the original 6203 - Portuguese or otherwise - was great in the Matchless G3, but was simply not designed to manage the shaft flex encountered on the 850, especially the 'A' models and Mk 3 with a higher second gear and 22T gearbox sprocket.
Click to expand...
In his gb rebuild DVD, Hemmings states he has seen layshaft breakages he believes were caused by roller bearings limiting shaft flex. He claims hundreds of box's done and no failures reported with his recommended phenolic cage bb. And of course many of those bikes were racers.
 
Bonzo said:
Would this be the bearing Mick used/recommended?

www.123bearing.co.uk

Deep Groove Ball Bearing 6203-TB-P63-FAG 17x40x12 mm

<p>The Deep Groove Ball Bearing, known as 6203-TB-P63-FAG FAG, has an inner diameter of 17 mm, an outer diameter of 40 mm and a thickness of 12 mm.</p>
www.123bearing.co.uk www.123bearing.co.uk
Click to expand...
The bearing I got from Mick Hemmings is labelled FAG 6203TB.P63 (made in Portugal) and thus seems to be same as your post.

Slick
 
Bonzo said:
Would this be the bearing Mick used/recommended?

www.123bearing.co.uk

Deep Groove Ball Bearing 6203-TB-P63-FAG 17x40x12 mm

<p>The Deep Groove Ball Bearing, known as 6203-TB-P63-FAG FAG, has an inner diameter of 17 mm, an outer diameter of 40 mm and a thickness of 12 mm.</p>
www.123bearing.co.uk www.123bearing.co.uk
Click to expand...

Yes, also listed as 6203TB-P6-C3.

FAG 6203-TB-P6-C3 Deep Groove Ball Bearings 6203.TB.HP63/FAG | Cromwell Tools

Deep groove ball bearings are versatile self-retaining bearings with solid outer rings inner rings and ball and cage assemblies. These products which are of simple design robust in operation and easy to maintain. Due to their low frictional torque deep groove ball bearings are suitable for high...
www.cromwell.co.uk www.cromwell.co.uk
texasSlick said:
The bearing I got from Mick Hemmings is labelled FAG 6203TB.P63 (made in Portugal)
Click to expand...

Now made in Korea.
 
texasSlick said:
The bearing I got from Mick Hemmings is labelled FAG 6203TB.P63 (made in Portugal) and thus seems to be same as your post.

Slick
Click to expand...
Funnily enough I'm just having a clear out, one of the items is a Hemmings/Quaife gearbox. The bearing that was fitted was that one but made in Germany, I have 2 spares, one I haven't seen a country of origin yet and the other was made in Portugal.

I guess it's likely that Mick supplied both, but can't say for sure.
Certainly it was on Micks recommendation though.

All FAG though.
 
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