So You Just Bought a Near Mint Condition Commando?

First of all I want to assure everyone that I am still extremely happy with the purchase of my '74 850 MK II Commando Roadster. I hold no-one responsible for the eventual outcome. It was just luck of the draw.

I do feel that it is imperative for me to to relate my experience in the hope that it may perhaps prevent a tragic occurrence from happening in the future.

Back in late September I made the purchase of a lovely "Fire Flake Blue" '74 Roadster. It was/is in very good to excellent overall condition (with one exception at present) and the appearance was that of a well cared for and maintained motorcycle with a thick folder of maintenance records. One thing missing from the maintenance records was any reference to work on the gearbox. I asked about the possible problems with the layshaft bearing and we discussed it at length. Seems that conventional wisdom was that the only models with this ticking time bomb were later MK IIIs with the "Portuguese" ball bearing.

I decided that given the excellent overall condition of the bike and the way it ran, I would go ahead and ride it for the reminder of of our short riding season. A gearbox rebuild would be the winter project priority and I went about doing some shake down riding to identify areas that needed attention. I stayed within about 25 mile from home..

On the day of my last ride I had noticed a bit of noise coming from the gear box after start up. I reached down with my hand to play with the shift lever and the noise ceased. I thought nothing more of it. I put in about 100 miles that afternoon/evening. As I was on my way home I slowed to a very low speed to make a left turn. When I shifted to low gear, I heard some clunking noises from the gearbox and the rear wheel locked up. Fortunately my low speed resulted in a short skid to a stop. I looked down and the kick starter was pointing to the ground. I am very fortunate that this occurred at a walking pace and not during one of the brief 90 mph sprints that occurred earlier in the day.

My point is, this is something that can't be judged by outward appearances. Unless the bike has reliable documentation of the replacement of the layshaft bearing, preferably with the roller bearing upgrade, you are rolling the dice if you ride the bike without going into the gearbox.

Right now I am moving 35 years worth of accumulated "stuff" into a new home (by myself) while simultaneously doing renovations so I can not take the time to work on the Norton. "Trixie" is in a nice garage for the down season. As soon as I get some semblance of normalcy here, I will purchase a motorcycle lift and rebuild the gearbox as well as sorting out some other less significant issues.

As you say, you were lucky it happened at low speed.

Dan1950 said:

Seems that conventional wisdom was that the only models with this ticking time bomb were later MK IIIs with the "Portuguese" ball bearing.

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No, all the info I have seen says it was worse with the 850's not just the MK3, my MK2a layshaft bearing grenaded in mid 80's as an example. However its still possible with any Commando and is regularly warned about on this site.

Well Dan, you have one thing that you need to do ASAP - go buy a lottery ticket!!

So glad that neither you nor the bike (nor anyone else for that matter) came to harm because of this.

The 850s twist a bit harder, especially at normal riding revs.
A friend who has made a business of rebuilding AMC boxes tells me that the 850s are a lot harder on the gearbox than the 750s.

Glen

worntorn said:

The 850s twist a bit harder, especially at normal riding revs.
A friend who has made a business of rebuilding AMC boxes tells me that the 850s are a lot harder on the gearbox than the 750s.

Glen

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So. what upgrades can I add to strengthen the gearbox? Is the layshaft roller bearing less prone to failure?

Sorry to hear this but it's not exactly unusual
I really would have thought that all of these layshaft bearings would have been changed by now?
Any movement of the Kickstart means the bearing is on its way
Yours must have just been grumbling as you could hear a noise!

Dan1950 said:

So. what upgrades can I add to strengthen the gearbox? Is the layshaft roller bearing less prone to failure?

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.

andover-norton.co.uk

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With the bearing upgrade your gearbox would have been fine
But now you will need to check everything
But with just the roller conversion the gearbox will be fine for your needs

baz said:

With the bearing upgrade your gearbox would have been fine
But now you will need to check everything
But with just the roller conversion the gearbox will be fine for your needs

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I plan to closely inspect all bushings and will probably replace all the bearings and of course seals.

baz said:

Sorry to hear this but it's not exactly unusual
I really would have thought that all of these layshaft bearings would have been changed by now?
Any movement of the Kickstart means the bearing is on its way
Yours must have just been grumbling as you could hear a noise!

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The engine and gearbox of the bike look like they have never been apart. In the service records that go back to 1997 there is no documentation of major internal work on either the engine or gear box. It has an even "patina", slight staining of the aluminum as well as some rust in the bottom of the cast iron cylinder fins. Given the compression and power from the engine it would seem that the 8000+ miles on the clock might be accurate.

Dan1950 said:

The engine and gearbox of the bike look like they have never been apart. In the service records that go back to 1997 there is no documentation of major internal work on either the engine of gear box. It has an even "patina", slight staining of the aluminum as well as some rust in the bottom of the cast iron cylinder fins. Given the compression and power from the engine it would seem that the 8000+ miles on the clock might be accurate.

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My Dad's Mk2 850 has never had the bottom end apart on it since he bought it in 1981 - the head was off once back in the mid 80's to do some valve work, but has not been off since. It was his main ride up until 1997, and still gets about 1000 miles per year put on it.

Good possibility it has not been apart.

The absolute FIRST THING I did was fit an oil pressure gage. A peek into the health of the rod bearings/oil pump. Peace of mind.

concours said:

The absolute FIRST THING I did was fit an oil pressure gage. A peek into the health of the rod bearings/oil pump. Peace of mind.

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It came with the Old Brits oil pressure gauge. I would like to add an idiot light for oil pressure in tandem with the gauge as well as charging . Can't really see the gauge when it's dark. It carries 15 psi at idle when hot about 40 psi when cruising.

http://improvingclassicmotorcycles.com

I fitted the combination charge/oil pressure warning light unit to my 1974 850

That is a buzz kill. Bike is still in one piece and so are you. Good luck with the move.

Dan1950 said:

So. what upgrades can I add to strengthen the gearbox? Is the layshaft roller bearing less prone to failure?

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.

andover-norton.co.uk

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The Layshaft bearing upgrade will get you a long way down the road. The problem you might have right now is damage to gears etc caused by the bearing debris.
Other than that, the stock box holds up to the 850s well enough. The worn 850 boxes my friend referred to were on high miles bikes.

Glen

Just one of the things you will come to expect when owning a Norton. If not that then it would be something else. This stuff occurs from Day 1 when brand new. They do make a mechanic out of you eventually.

baz said:

I really would have thought that all of these layshaft bearings would have been changed by now?

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Not hardly...

Make sure your wheel bearings are repacked or put new sealed bearings in.

Unless it has already been done, the headstock bearings are due for a service as well.

Check when your fork oil was last changed.

Drain and flush brake fluid.

Ride.

batrider said:

Just one of the things you will come to expect when owning a Norton. If not that then it would be something else. This stuff occurs from Day 1 when brand new. They do make a mechanic out of you eventually.

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5 years riding a BSA A65T and 20 years riding a '64 Panhead already made a mechanic out of me. I managed to make the Panhead dead reliable. The BSA? Not so much.