Measurement please

[seattle##gs]

I have some extra room (3/32) in the swingarm / rear wheel department. If someone could measure the distance between the tips of the swing arm...outside dimension please, I'll compare it to what I have. Bare swing arm of course. The next possibility is the 520 sprocket / brake drum and stub axle is slightly off. I can make a spacer to solve the problem but I want to know where the problem is. Thanks.

 

[L.A.B.]

8 1/8" inside to inside so approximately 8 3/4" outside to outside.

Thread 'Rear axle fitment'

Jun 12, 2023

Need some help/suggestions on getting my rear axle spacer to fit between the speedo drive and the fork ear. I am coming up almost a 1/4” short of space. I have tried two sets of cush rubbers, one set made shorter to try to get drum closer to hub. Didn’t seem to make much difference. Speedo drive is tapped onto the hub. I have converted to one piece axle assembly with adapter installed. Adapter is right up against bearing on the inside of hub. Distance between rear fork ears is 8”, spacer is a hair over 1-1/4”. I have thought about narrowing spacer or trying to widen distance...

• jamesp
• Replies: 30
• Forum: Norton Commando Forum

 

[marshg246]

I have some extra room (3/32) in the swingarm / rear wheel department. If someone could measure the distance between the tips of the swing arm...outside dimension please, I'll compare it to what I have. Bare swing arm of course. The next possibility is the 520 sprocket / brake drum and stub axle is slightly off. I can make a spacer to solve the problem but I want to know where the problem is. Thanks.

As @L.A.B. said, 8-1/8" between. If you look form behind with no wheel installed you will likely see that one of the two sides is bent - the flat part, not the tube part. They are actually easy to bend back into place. I use an old axel and a fork tube to do it.

 

[TJBaker57]

Continuing my tendency towards what someone described as "a whiff of overkill"....

Is there a documented centerline offset value expected/established at the rear wheel axle point?? ie: is the center of the 8.125" expected to NOT be the same as the centerline of the engine cradle??

Some time ago as I was inventorying what I have here I set about to check out my swingarm and the swingarm to cradle alignments.

Checked for parallel engine cradle plates, parallel swingarm axle plates, possible twisting of the swingarm and so forth.

In doing so I saw that the centerline of the engine cradle and center at the rear axle are offset. In my case the center of the rear axle space is roughly 3/16" towards the timing side vs the centerline of the engine cradle.

 

[L.A.B.]

In doing so I saw that the centerline of the engine cradle and center at the rear axle are offset. In my case the center of the rear axle space is roughly 3/16" towards the timing side vs the centerline of the engine cradle.

Correct as the cradle (therefore the engine and front end of the swinging arm) are offset to the left of the frame centre as is the head steady.
The axle plates however, must be centred to the frame or the shocks would lean over so the swinging arm isn't exactly symmetrical.

 

[TJBaker57]

Correct as the cradle (therefore the engine and front end of the swinging arm) are offset to the left of the frame centre as is the head steady.
The axle plates however, must be centred to the frame or the shocks would lean over so the swinging arm isn't exactly symmetrical.

Thank you, that's good to know.

Was just now digging through shelves, boxes, bins, coffee cans and so on gathering up what parts I think go with the rear axle etc to see that I have everything and it fits in the space.

But someone decided it was break time... She lives in the shop but wants more people time. So I am hounded relentlessly when she wants time. She hopped up on top of the wheel as I was trying to mate it to the brake drum.

 

[Schwany]

I have some extra room (3/32) in the swingarm / rear wheel department. If someone could measure the distance between the tips of the swing arm...outside dimension please, I'll compare it to what I have. Bare swing arm of course. The next possibility is the 520 sprocket / brake drum and stub axle is slightly off. I can make a spacer to solve the problem but I want to know where the problem is. Thanks.

If all the correct parts are there and you have 3/32" of slop, which isn't much, it is possible that the speedo drive in the hub locked up on the speedo and started winding out of the hub, which will spread the swing arm on the speedo side if the cable winding up doesn't stop the rear wheel from spinning. Been there with a Norton, but not on a Commando. It's probably what Greg said though. Just the ear is bent.

 

[seattle##gs]

Tonight I start the deep dive into the problem. It could very well be a bent ear though usually when an axle nut is tightened it will shift the opposite nut either foreword or backward and it does not appear so but will get another inspection. Sadly, the swingarm just got powder coated.

 

[marshg246]

Tonight I start the deep dive into the problem. It could very well be a bent ear though usually when an axle nut is tightened it will shift the opposite nut either foreword or backward and it does not appear so but will get another inspection. Sadly, the swingarm just got powder coated.

I looked for the picture of how I do it, but can't find it.

If you put an axel through the slot and put rubber or cloth between the hex of the axle and the swingarm plate, you can bend it back without hurting the paint/powder coat. Don't push real hard - they straighten surprisingly easily. The last one I did both sides were bent towards the drive side but the timing side was bent more - I only had 7-7/8" between the plates.