I'm a newby, so apologise if this has been covered. I read the "Crooked Norton" thread and thought I'd add my $.02
When I first got my '72 Commando barn bike running, I aligned the rear wheel with string, then "road tuned" it with hands-off coasting in 4th gear. I tweaked the rear adjusters until all tendency to side drift disappeared. This is the way I've always set alignment. Trouble was, with the bike coasting straight, it had a slight lean to one side. Never had a bike that did that. Then I noticed it handled slightly differently in right verses left corners. Not a huge difference, but it was real. It would drop into right hand corners, eager as a puppy, but had to be asked politely to go left.
When I checked the front wheel, the rim was offset 1/4" to the left. To my mind, there is no way a bike can be aligned if the front wheel is offset from the steering stem axis. Sure, you can get the 2 wheels to point in the same direction (by turning the back wheel with the adjusters so it no longer aligns with the steering stem either) and the bike will pass the "string test". But now neither wheel is aligned to the frame.
I went to a British bike meet and checked every Norton. 90% of the right-sided-disk Nortons were offset 1/4" to the left. Stick a finger on each side of the rim to gauge the distance to the fork slider. You don't need a micrometer.... this is not subtle.
I had the rim replaced (rusted from 17 years in a barn) and told the bike shop I wanted the offset removed. They assured me they would do it right and would lace my new rim exactly to factory specs. They had a brand new laced wheel straight from Andover they could compare it with, just to be sure.
The new wheel had the same 1/4" offset and the bike handled the same. I had them adjust the spokes until the wheel was centred. Now the bike tracks straight and handles the same right/left.
My theory: When Norton adopted that hulking huge Lockheed caliper, they had to get the spokes out of the way. That's why the hub is asymmetric and the "cone angle" of the right side spokes is flatter than the left side. The "cone angle" of the spokes determines the tension on the spokes under wheel side load. Flatter cone, higher load. (It's a trigonometry thing). That's why Norton uses thicker spokes on the right side than the left. I think some engineer got the willies and offset the rim to the left to increase the cone angle and reduce the spoke tension.
As a result, the world has crooked Nortons. I know it sounds ridiculous that Norton would deliberately mis-engineer the bike. But they do have a history of bad engineering. Look at that disk brake! It is the worst brake ever installed on a motorbike!
So, for anyone interested in a straight Norton, align your front wheel with the forks before aligning the back wheel with the front. Then both wheels will be aligned with the steering stem, instead of neither.
When I first got my '72 Commando barn bike running, I aligned the rear wheel with string, then "road tuned" it with hands-off coasting in 4th gear. I tweaked the rear adjusters until all tendency to side drift disappeared. This is the way I've always set alignment. Trouble was, with the bike coasting straight, it had a slight lean to one side. Never had a bike that did that. Then I noticed it handled slightly differently in right verses left corners. Not a huge difference, but it was real. It would drop into right hand corners, eager as a puppy, but had to be asked politely to go left.
When I checked the front wheel, the rim was offset 1/4" to the left. To my mind, there is no way a bike can be aligned if the front wheel is offset from the steering stem axis. Sure, you can get the 2 wheels to point in the same direction (by turning the back wheel with the adjusters so it no longer aligns with the steering stem either) and the bike will pass the "string test". But now neither wheel is aligned to the frame.
I went to a British bike meet and checked every Norton. 90% of the right-sided-disk Nortons were offset 1/4" to the left. Stick a finger on each side of the rim to gauge the distance to the fork slider. You don't need a micrometer.... this is not subtle.
I had the rim replaced (rusted from 17 years in a barn) and told the bike shop I wanted the offset removed. They assured me they would do it right and would lace my new rim exactly to factory specs. They had a brand new laced wheel straight from Andover they could compare it with, just to be sure.
The new wheel had the same 1/4" offset and the bike handled the same. I had them adjust the spokes until the wheel was centred. Now the bike tracks straight and handles the same right/left.
My theory: When Norton adopted that hulking huge Lockheed caliper, they had to get the spokes out of the way. That's why the hub is asymmetric and the "cone angle" of the right side spokes is flatter than the left side. The "cone angle" of the spokes determines the tension on the spokes under wheel side load. Flatter cone, higher load. (It's a trigonometry thing). That's why Norton uses thicker spokes on the right side than the left. I think some engineer got the willies and offset the rim to the left to increase the cone angle and reduce the spoke tension.
As a result, the world has crooked Nortons. I know it sounds ridiculous that Norton would deliberately mis-engineer the bike. But they do have a history of bad engineering. Look at that disk brake! It is the worst brake ever installed on a motorbike!
So, for anyone interested in a straight Norton, align your front wheel with the forks before aligning the back wheel with the front. Then both wheels will be aligned with the steering stem, instead of neither.