Layshaft bearing failure

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rons70commando

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Feb 22, 2010
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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 is not presenting any of the symptoms commonly reported when the bearing is starting to die. I have the mechanical skill to take the thing apart and check/replace the bearings and all the other bushings and seals. Does this fall into the "better safe than sorry" caegory?
Thanks in advance for your opinions.

1999 R1100rt
1970 Commando Roadster
1971 XLH Boat tail Sportster
1959 Duoglide Panhead
2010 Concours (just arrived)
 
Given the potentially disastrous (for the bike and for your health/life) consequences of a layshaft bearing failure at speed, I'd say so, yes.

When I did mine I thought I might be wasting my time, as I'm the fourth owner (supposedly) and no service history whatsoever. Figured I'd do all the work only to find a good roller bearing in there.

Found a ball bearing. With the word "Portugal" stamped on it.

Better safe than sorry, yes!

If you want to potentially save some work, you can dissassemble the gearbox in situ and see if you've got a quality bearing in there already. If so, just reassemble. If not, you'll need to take the primary off and possibly remove the gearbox from the frame (not strictly necessary, I'm told, but it sure makes working on the box easier).

Best of luck.
 
My '71 Roadster w/ '75 running gear and powertrain had the mickeymouse Portugese layshaft bearing. I replaced it with Timken when I replaced the broken 2nd gearset. I think later models are more likely to have substandard parts than earlier other than the Superblends, which became standard after many crank/case faliures
 
The Mk3 had the most problems with layshaft bearings but all years have had some problems and failure has the potential to create a hazardous situation. I wouldn't recomend riding any Norton without knowing what was in it for a layshaft bearing. Been there done that. Jim
 
comnoz said:
The Mk3 had the most problems with layshaft bearings but all years have had some problems and failure has the potential to create a hazardous situation. I wouldn't recomend riding any Norton without knowing what was in it for a layshaft bearing. Been there done that. Jim
Click to expand...

And there's the validation.
 
This, and the chain, used to prey on my mind. I'd be cruising along on some highway (didn't really worry about it in other contexts, which is semi-silly at best) and thinking....my layshaft bearing may give out...or that f'ing chain give out....and I'm on my ass skidding down this highway with these Massachusetts LUNATICS trying to kill me....

Did the layshaft bearing (and whatever else the gearbox needed, including by the way two sets of gears along with the usual bushings, o-rings, etc.) and a 520 x-ring chain and I can ride with some level of peace of mind now.

Of course, the MASSHOLES are still out to get me, but I may be able to outrun them now.... :p
 
Hey Brian,
I can just see you driving down RT. 128 during the Friday afternoon crush running a sketchy layshaft bearing and a worn chain, and you are refering to the other drivers as "LUNATICS".
GB
 
Hey, welcome to the forum Ron! You'll get plenty of help around here as you've seen. Got any pictures of your Norton?
 
As far as I know when the layshaft bearing is on its way out it will show by the kickstart starting to flip back while accelerating.I thought this was common and normal when I came back from my honeymoon from Scotland 27years ago .This was with the wife and camping-gear (for 3 weeks).I got back and replaced the bearing at home .So it does not go bang in moment .However having replaced one at the roadside in Germany (on the Late Terry Hobbs bike )together with Monty (Hobbs mech ,great bloke)I know there are better ways to do it .I would give it a blast or better a fast run and keep an eye on the kick.Things are different if you plan to take it for a 3000mile tour or so then I would replace it anyway .
ps i would get rid of the tractors in your collection and spend some quality time on the Norton ,
 
The failure mode on the bearing is for the cage to disintergrate, this allows the balls to move all to one side and the bearing inner and outer races can push to one side, exit balls into gearbox :shock: . Most times the balls fall into the sump and sit there :D , sometimes they jump up and jam between the rotating gears and are broken up :) , some times they will jam in the gears and lock the box up :cry:

From first signs eg the kickstart falling backwards to only having 4th gear took 10 miles for me, got all the evidence of the loose balls in the sump but luckly no lockup.

Waiting for the symptoms before fixing is not recommended IMHO
 
You may or may not get a warning (wandering kickstarter) of imminent failure.

Geo46er, exactly so!
 
kommando said:
The failure mode on the bearing is for the cage to disintergrate, this allows the balls to move all to one side and the bearing inner and outer races can push to one side, exit balls into gearbox :shock: . Most times the balls fall into the sump and sit there :D , sometimes they jump up and jam between the rotating gears and are broken up :) , some times they will jam in the gears and lock the box up :cry:

From first signs eg the kickstart falling backwards to only having 4th gear took 10 miles for me, got all the evidence of the loose balls in the sump but luckly no lockup.

Waiting for the symptoms before fixing is not recommended IMHO
Click to expand...

+1 on not waiting for symptoms.

When the layshaft bearing went out on my first Commando (1973 850) there were no warning signs whatsoever. The gearbox locked up at 60 mph on the highway and I skidded to a stop in the middle of the road. I was lucky - I'd just come out of a corner and there was no traffic behind me.

The failure was just as kommando described - the cage broke apart and the balls all became free agents.

Both of my current Commandos had the original layshaft bearing when I opened up their gearboxes. Assuming it's been replaced by a previous owner could be a fatal mistake.

Debby
 
Hi:
Mine failed on my 71 which I had bought new at about the 30,000 mile mark.Not fun.At least I was in town and it just slid locked up.Pulling in the clutch makes no difference,that is why it is so DANGEROUS. As to what years it can affect,it can affect any. Back then the dealer was dealing with the same problem on many once they had mileage on them. As I recall the roller bearing had not been brought into the solution,so we just put a new bearing in.
Someone in the INOA I believe came up with the roller bearing.I have replaced everyone in every rebuild I have done since wether it possibly needed it or not.
Bruce
 
[album][/album]Mine just went tonight. I've owned the bike for 23years. I had always hoped that a previous owner had replaced it since I've racked up so many miles without a problem. All of the older timers had warned me about the layshaft for years so when the bike seemed to drop out of gear at a stop I checked my kick start lever and it did seem maybe a hair low. Someone was trying to make a u-turn right on top of me though so I flew on down the hill only to feel the sensation of something grabbing my rear wheel and then letting it go into a serious power slide. My kick start lever dug a furrow in the street and probably helped me keep some control ( like a rudder ) I dread what I'm going to find when I open the case .
 

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Still Vertical , and Still Moveing . Glad to hear your O.K. , may not be all disaster in there .Though Id roll the shafts on a sheet of glass to see if they bent ,Hopefully it just locked rather than tore up .
 
WheeWhhee doggiedoo! What a sensational image complex for you to mull over a long time. When your head and heart allow it please detail the physics and actions you experienced. Just in case, keep in mind Atlas shells work better than the Commando'$. Bet ya also got the loose kick lever spline syndrome now too, nah nah nah nah nah, ugh.
 
I checked mine because I had the bike apart. The tranny felt great, no problems with the kick start, shifted very nice but had a howl in second. This is what I found
Layshaft bearing failure
 
Wow! Those are some heart stopping stories! i am helping a fellow Colorado Norton Club member replace his layshaft bearing now. We are doing it while in the frame. You will need an "inside puller" and some heat to get the old bearing. You will also need a clutch and sprocket puller to get the sprocket off so that you can pull and inspect the mainshaft. Take a close look at all of the bushings/bearings while you are in there also.
Good luck!
Mike
 
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