Axle break

interesting reading for me as my commando is missing the back axle and the 3 nuts that hold the back wheel on I am trying to figure out what the thread size is on the axle and the 3 missing nuts ........whitworth or?
does someone make a replacement axle of better quality ?
I have one of the first thousand commandos made still with the widowmaker frame I am assuming the atlas axle and hub nuts are the same for this model ?
thanks
Sean

The early axle is different than 71 and newer. No cush drive too. Those nuts are 06.0323, I'm sure they're available. They're 7/16-20 UNF, but they're a special sleeve nut with a hex on the end. Pretty much like a wheel nut, but longer. I've been trying to get Madass to make a stainless single part rear axle for the early bikes, but it's not big on his list.

You can also use the newer cush drive axle, but you'll have to get the newer drum and all newer parts, the swing arm is the same. Others have done it.

Dave
69S

The Norton rear wheel axle sure has a small diameter for its length, which unfortunately makes the axle relatively elastic. So, I would think that torquing the axle bolt is more critical on a Norton as compared to other motorcycles. I believe the recommended torque is 80 foot-pounds. There's quite a lot of dynamic load on the axle itself, and tightening the bolt reduces its elasticity.

One thing I noticed about my Norton's rear axle is that the threads are cut not rolled, which really surprises me in a highly stressed part. I would think that rolling the threads would go a long way in extending the life of the axle. Gosh it sure would be nice if they would roll the threads on the axle assembly!

There is a spacer that is pressed into the double roll ball bearing which is mounted in the brake drum. This spacer was apparently made too soft and would actually wear out causing the axle to loosen. Not only that, I imagine that there would be a rocking action on the axle itself putting bending loads on the threaded portion of the axle which could cause the axle to fatigue and break. Norton addressed this problem by superseding the original spacer (Part Number 062070) to the new spacer (Part Number 065290). The Norton 850 Mark 2 and 2A's should already have that new spacer. Unfortunately,there are no identifying marks on the superseded spacer. So, I would recommend when replacing the axle go ahead and replace that spacer as well.

DogT said:

The early axle is different than 71 and newer. No cush drive too. Those nuts are 06.0323, I'm sure they're available. They're 7/16-20 UNF, but they're a special sleeve nut with a hex on the end. Pretty much like a wheel nut, but longer. I've been trying to get Madass to make a stainless single part rear axle for the early bikes, but it's not big on his list.

You can also use the newer cush drive axle, but you'll have to get the newer drum and all newer parts, the swing arm is the same. Others have done it.

Dave
69S

Click to expand...

thanks for the info ...... if I could find a drawing for the axle I could make one
Sean

I have this theory about broken axles and it has to do with the sequence of assembly. Although there may be other circumstance that cause failures (bearing seizures, no lube, etc), I think this can save many axles from premature breakage.

Let's say you have the brake assembly in place but the dummy axle is still loose for the purpose of aligning the rear wheel or whatever. Then you bring the tire into position and put the main axle in. You check you chain slack, alignment or whatever then torque you main axle to spec.

This is where we get into trouble. We are all aware of how the dummy axle floats a bit. After the main axle is torque this dummy axle is brought to a position by the main axle which at this time has been both torqued and now out of position and if not close to be bottomed out then possibly quite near.

At this point we attempt to torque the dummy axle nut on the drive side and pull the dummy axle in toward its home position causing the main axle to stretch beyond spec and is ready to fail (sooner or later) at its weakest point. Guess where that is? Correct! Right at the base of the threads.

Always torque Dummy axle first, THEN main axle.

So, is it the consensus that the two piece axle will eventually break? Or only if it's overloaded (fat people AND gear)? Or is the improper/over tightening the kiss of death?

Absolutely yes at some point they all will break if ridden at the known proven stress riser on an axle diameter that will be flexing some in that location d/t the cushion mating loose zone, that's why I call them radioactive with a half life that could be calculated if we had more data base to go by, but assuming a half life in the decades it don't mean they all or even yours will break in your life time - unless of course abusing loadings. Part of the Norton Commando mystique - how luck do ya feel...

Ok, Ok, Ok, .............I'm ordering a one piece axle tomorrow. I don't have to be told more than 13 or 14 times before I get the point.

BTW, I took the rear wheel apart today and Hobot was right on, axle broke right at the last thread. A cold saw probably couldn't make a cleaner cut.

Diablouph said:

Ok, Ok, Ok, .............I'm ordering a one piece axle tomorrow. I don't have to be told more than 13 or 14 times before I get the point.

BTW, I took the rear wheel apart today and Hobot was right on, axle broke right at the last thread. A cold saw probably couldn't make a cleaner cut.

Click to expand...

Where do you order a one piece axle from then? US? or any in UK?

Old Bloke said:

Diablouph said:

Ok, Ok, Ok, .............I'm ordering a one piece axle tomorrow. I don't have to be told more than 13 or 14 times before I get the point.

BTW, I took the rear wheel apart today and Hobot was right on, axle broke right at the last thread. A cold saw probably couldn't make a cleaner cut.

Click to expand...

Where do you order a one piece axle from then? US? or any in UK?

Click to expand...

This is the only one I know about. Madass140 has them.

http://www.ebay.com/itm/Norton-ONE-PIEC ... 0759239062

Thanks for the link, I searched for norton one piece axle, but I must have had the "UK only" filter switched on, doh! Sometimes I wish I lived in the USA

Looks nice. Stainless steel? I like SS, but I thought the concencus was that it wasn't a good material for axles, or was that just for the original design rear axle?

No buy it now price unfortunately.

Yeah, I'm trying to buy this one, reading this forum makes me paranoïac

Xpongebob said:

Yeah, I'm trying to buy this one, reading this forum makes me paranoïac

Click to expand...

Paranoiac's are under the delusion that they are being persecuted.

Norton owners understand it's reality.

Damnnnned

:evil:

Anyway, made 300 miles today, topped at 110 Mph, which is more than enough, and wondered when this evil axle was going to break !

If you want a one piece, just PM Madass140 directly. He'll gladly ship one out to you.
I have one of his one piece axles on my alloy project, there is no way you will ever break it.

Xpongebob said:

Damnnnned

:evil:

Anyway, made 300 miles today, topped at 110 Mph, which is more than enough, and wondered when this evil axle was going to break !

Click to expand...

I was doing 25 - 30 when mine let go. Quite enough of a thrill for me.