Layshaft bearing failure

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Jeepers Doug! You shouldn't post images like that without a warning! If my wife were to see that she might make me buy a better life insurance policy.

Russ
 
It sure beats a picture of bloody hands and knees after a high-side in jeans without gloves. It's no fun dragging a locked up Commando to the shoulder of I25 with cars going by at 70 mph.

The factories suggested roller bearing replacement cures that problem for good. Jim
 
comnoz said:
It sure beats a picture of bloody hands and knees after a high-side in jeans without gloves. It's no fun dragging a locked up Commando to the shoulder of I25 with cars going by at 70 mph.

The factories suggested roller bearing replacement cures that problem for good. Jim
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I forgot to put the sarcasm icon on my post. I think the photo speaks loudly as to why you should check that bearing regardless of whether you detect any problems with the gearbox! One of the things really amazing about a lot of old machinery, Commandos included is how well it will function despite problems with it. If you are limping home in a B-17 its a good thing, if you are riding at high speed with bearings that are falling apart...not so good.

Russ
 
rvich said:
comnoz said:
It sure beats a picture of bloody hands and knees after a high-side in jeans without gloves. It's no fun dragging a locked up Commando to the shoulder of I25 with cars going by at 70 mph.

The factories suggested roller bearing replacement cures that problem for good. Jim
Click to expand...

I forgot to put the sarcasm icon on my post. I think the photo speaks loudly as to why you should check that bearing regardless of whether you detect any problems with the gearbox! One of the things really amazing about a lot of old machinery, Commandos included is how well it will function despite problems with it. If you are limping home in a B-17 its a good thing, if you are riding at high speed with bearings that are falling apart...not so good.

Russ
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Oh it was taken as you intended. I was just remembering my first experience with the infamous Norton layshaft bearing. Jim
 
I had a similar experience except it was on a back road and there was no other traffic at the moment the lockup occurred. I still don't know how I managed to drag that bike to the side of the road. Adrenaline I suppose.

That photo is just what my failed bearing looked like except there were only three or four balls left between the races. The rest had ejected and were bouncing around inside the gearbox. That gave the layshaft quite a bit more free play than the designers intended.

There was no warning, it just locked up. Not something I want to experience again.

Debby
 
On the bearing race relation to its bore, AMC shells are way too famous for being worn to the lose side, so race is expected to come out with the shaft once fairly warm to hot long enough. The issue will be - is bore not further damaged to accept new style roll bearing and not spin and wobble in its bore at operating temps. Check shaft run out and realize they don't bend like a stick more like a candy cane twist. If ya a stand and all go ahead and tackle gb mounted but to do so is only a few steps away from removing it for the leisure at hand on a bench.
Besides can get to them hard to clean spots.
 
debby said:
I had a similar experience except it was on a back road and there was no other traffic at the moment the lockup occurred. I still don't know how I managed to drag that bike to the side of the road. Adrenaline I suppose.

That photo is just what my failed bearing looked like except there were only three or four balls left between the races. The rest had ejected and were bouncing around inside the gearbox. That gave the layshaft quite a bit more free play than the designers intended.

There was no warning, it just locked up. Not something I want to experience again.

Debby
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I don't recall mine ever giving me a warning either. Of course I had never heard of it at that time [late 70s] so I probably wouldn't have paid any attention anyway. I was at the end of the 13th street on ramp to I-25. I glanced back to see if I had room to merge and the next thing I knew the rear end was swinging from side to side. I stayed on until I had slowed down a lot but when it caught it tossed me a good 15ft. It could have been a lot worse. All the cars missed me. Jim
 
I was lucky. I had just come out of a corner when it locked up. I managed to slither to a stop without crashing. It was exciting, but not in a good way.
 
Me too, ripping up a long steep hill at roughly a ton in third she nipped up. Clutching did nothing, but changing into forth freed her off and I managed to limp her to the nearest petrol station for a look see. I found the bearing had broken up and half had blown out of the gearbox, the other half was somewhere on the hill. The black line was impressive and so to the brown.
I've got to admit it had given me a warning a few days before, I'd even bought a bearing and had planned to replace it the very next month.

Cash

PS I had a Ferrari up my arse at the time, probably scared the life out of him too, so thanks Kevin for backing off.
 
Somehow got on this post after looking for a descent glove for summer. I spoke to my mechanic Bobby at Johns cycle center in Queens, he said he never heard of any problems and that it will give you an indication well in advance, problems shifting, noises in the gearbox ... He's specializes in English bike repair and thought it wasn't necessary?? He said might as well replace them all if you open up the gearbox. Is it the layshaft specifically or any one with ball bearings? don't want to fixate on this one, but can't afford another accident.
 
take for what it is worth but a standard ball bearing WILL FAIL. as to your SO CALLED British bike specialist that statement would tell me to find a different shop, one that KNOWS norton's

73Norton said:
. I spoke to my mechanic Bobby at Johns cycle center in Queens, he said he never heard of any problems and that it will give you an indication well in advance,
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It's not a big job and with all the documented troubles over the years, why wouldn't you check and replace if necessary? My gearbox was working fine, but, sure enough, when I went in there I found the original bearing. It had no apparent problems, and it might go another 13,000 miles or it might do what that one it the previous post did. All it takes is one ball to wedge in to the teeth and nothing but bad happens.
 
When I started this thread a month or so ago, I han't started the project. Since then I ordered all new bearings, bushings and gaskets from Mick Hemmings, opened up the box and replaced all the worn parts. All of the bearings looked like they could have gone a long way further but I replaced them anyway. I left the gearbox case in the frame and the work pretty much went trouble free. I also put new friction discs into the clutchpack. Now I don't have to worry about the box seizing up at speed; I will find something else to worry about.

I am glad that I went ahead and performed the work. BTW the bike shifts and clutches much better than before.

Cheers! Ron
 
Fair enough I have enough idiots on the road in Brooklyn last thing I need is the bike to skid out and get run over. So just to be thorough how many bearings should I change out. The new ones don't have the balls in them. Excuse my lack of mechanical expertise just want to do them all in one shot and from my knowledge their is more to replace then just the layshaft.
 
73 Norton,
I replaced my lay-shaft bearing this winter as a preventative measure and after talking to Fred at Old-Brits,I also
installed both the bearing on the inner cover and the one for the sleeve gear while everything was apart.They are not
that much more to purchase for the piece of mind.
YING
 
cool, so is the layshaft the only bearing that has a potential to drop into the gears or are all 3 just as hazardous? Old Britts doesn't have the layshaft bearing ,where did you buy it? lastly Fred said he liked the Andover Norton bearings but I know many people speak highly of the Hemmings bearing, although Mick uses a ball bearing in his own bike(I believe this is a very expensive racing part that is not made like the originals that are breaking.) Want to get this fixed asap but want to make sure it's resolved in one shot. thanks, Christian
 
any good bearing supply should be able to get you one. the number you want is NJ 203-C3


73Norton said:
Fair enough I have enough idiots on the road in Brooklyn last thing I need is the bike to skid out and get run over. So just to be thorough how many bearings should I change out. The new ones don't have the balls in them. Excuse my lack of mechanical expertise just want to do them all in one shot and from my knowledge their is more to replace then just the layshaft.
Click to expand...
 
A lot of people have recommended the Hemmings FAG 6203TB? would the bearings for the main shaft
output, and the mainshaft bearing be the same part number or different. If different any one know the part numbers of the other 2 bearings to replace. Thanks! Christian
 
the other bearing numbers are main shaft RLS-5-2RS and sleeve gear is RLS-9-2RS you can either remove the seals on both sides or just remove the one that faces to the inside of the gearbox.

73Norton said:
A lot of people have recommended the Hemmings FAG 6203TB? would the bearings for the main shaft
output, and the mainshaft bearing be the same part number or different. If different any one know the part numbers of the other 2 bearings to replace. Thanks! Christian
Click to expand...
 
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