Rear Wheel '72 Commando

pete.v said:

Mcdammits pictures.

By looking at your shocks, I would say your swing arm is sprung to the left. It seem the left shock is splayed out at the bottom compared to the right. Appears to be enough to misalign the sprockets as mentioned. Looking at my own and putting a bubble level along the springs, both shocks will cant out a few degrees equally. Your right shock appears to be actually canted in at the bottom ever so slightly.

Click to expand...

Shock absorbers shouldn't definitely not be canted in or out a few degrees. They need to be at 90 deg. to the swing arm spindle axis looking from the rear of the machine and parallel looking from the side. Otherwise as the swing arm moves and the shocks compress friction is created between the rods and bushes in the shock body because the 'canted' angle increases. This is not good, then again if you don't go any where.....

Well measuring the hub offset I got 0. The wheel and hub are on center with each other. So I guess the thing to do is pull the swing arm, check for straightness and off set the wheel to hub 3/16 left,yes? Anybody got a straight swingarm I could borrow? Could I straighten my swingarm, then gusset it?

mcdammitt said:

Well measuring the hub offset I got 0. The wheel and hub are on center with each other. So I guess the thing to do is pull the swing arm, check for straightness and off set the wheel to hub 3/16 left,yes? Anybody got a straight swingarm I could borrow? Could I straighten my swingarm, then gusset it?

Click to expand...

Guess away! Welding will create distortion which, judging by your photo's, you've already got too much of. I've got an idea, why not look at http://www.vintagenet.us/phantom/wsc.html or have I mentioned that already?

Or you could do the 3/16" offset thing because I guess if enough people say it enough times then that will make it true and every thing will be o.k with your bike, there you go.

Looks to me more like an extra spacer behind L shock lower mount adding to the bow legged look but i can assure you if your swing arm is sprung to the L it would also be twisted so wheel/axle would appear tipped out of square too. The power unit is shifted to L ~3/16" but swing arms are asymmetrical with R leg angled out more to bring hub back in line with stem. We've a report of serious sa distortion just tacking on the chain guard mount tab so expect serious distortion welding in gussets. I sent pre-Peels swing arm that sprung out of shape so would not pass spindle back in again to GT Enterprises famous frame straightener who sent it back still unable to pass spindle so got 850 sa and lived happy ever after, with rim spoked to center tire in loop & stem, while mounted on bike so no guessing and no measuring just good eye balling to string line.

mcdammitt said:

Well measuring the hub offset I got 0. The wheel and hub are on center with each other. So I guess the thing to do is pull the swing arm, check for straightness and off set the wheel to hub 3/16 left,yes? Anybody got a straight swingarm I could borrow? Could I straighten my swingarm, then gusset it?

Click to expand...

Yes, the older type will tweak easier then the new type, of course that is why it's not right today. Reinforcing should also be a piece of cake.

I would create a spacer the exact distance that it is when the hub is in place. Secure it with a through bolt or threaded rod and nuts at each end and flex it back to the home position. I would do this cold(not heated). Test it in the frame with the hub/wheel installed and adjust as needed. With the made up spacer relocated, gusset as per the 850's. You'll be riding no hand in no time.

pete.v said:

mcdammitt said:

Well measuring the hub offset I got 0. The wheel and hub are on center with each other. So I guess the thing to do is pull the swing arm, check for straightness and off set the wheel to hub 3/16 left,yes? Anybody got a straight swingarm I could borrow? Could I straighten my swingarm, then gusset it?

Click to expand...

Yes, the older type will tweak easier then the new type, of course that is why it's not right today. Reinforcing should also be a piece of cake.

I would create a spacer the exact distance that it is when the hub is in place. Secure it with a through bolt or threaded rod and nuts at each end and flex it back to the home position. I would do this cold(not heated). Test it in the frame with the hub/wheel installed and adjust as needed. With the made up spacer relocated, gusset as per the 850's. You'll be riding no hand in no time.

Click to expand...

Reference to distortion due to welding http://www.lincolnelectric.com/en-gb/su ... etail.aspx

Appreciate all the help, I bought another swing arm. I will install tomorrow and see what happens. But I will have a spare to mess with..... :roll:

Pete ,when I was building my Norton I actually did the final truing of the rear wheel with it on the bike so that I was sure that the center of the crown of the tire was right on centerline of the frame. I don't know if this is the "correct" method,but it made sense to me at the time.

phillyskip said:

Pete ,when I was building my Norton I actually did the final truing of the rear wheel with it on the bike so that I was sure that the center of the crown of the tire was right on centerline of the frame. I don't know if this is the "correct" method,but it made sense to me at the time.

Click to expand...

That may be how Buchanan got their numbers. I do know that centerline of the frame is not the same as center in the swing arm. I think if right, the tire will ride 1/8 to 3/16" to one side. Mine is closer to the swing arm on the drive side by about an 1/8 to 3/16". I check my offset right after talking the son of the master at Buchanan's and mine just .045 shy of their numbers (about 3/64). Close enough for me.
Just to repeat from before. Buchanan says 1 9/16" from the machined surface of the cush drive hub to the center of the rim.

I guess the real question is how does it go down the road?

It's kinda crazy with the obscene offset of the front yet it's the rear begs for perfection.

pete.v said:

phillyskip said:

Pete ,when I was building my Norton I actually did the final truing of the rear wheel with it on the bike so that I was sure that the center of the crown of the tire was right on centerline of the frame. I don't know if this is the "correct" method,but it made sense to me at the time.

Click to expand...

That may be how Buchanan got their numbers. I do know that centerline of the frame is not the same as center in the swing arm. I think if right, the tire will ride 1/8 to 3/16" to one side. Mine is closer to the swing arm on the drive side by about an 1/8 to 3/16". I check my offset right after talking the son of the master at Buchanan's and mine just .045 shy of their numbers (about 3/64). Close enough for me.
Just to repeat from before. Buchanan says 1 9/16" from the machined surface of the cush drive hub to the center of the rim.

I guess the real question is how does it go down the road?

It's kinda crazy with the obscene offset of the front yet it's the rear begs for perfection.

Click to expand...

When all is said and done. IMO.... The rear wheel needs to be aligned with the front wheel (which is central to forks, which is central to frame or supposed to be) The relationship of rear wheel to swingarm is irrelivant.. The rear wheel needs to follow the front wheel on the same centreline, which usually needs a bit to the right hand side ... Or am i wrong????....

"When all is said and done. IMO.... The rear wheel needs to be aligned with the front wheel (which is central to forks, which is central to frame) The relationship of rear wheel to frame and swingarm is irrelivant.. The rear wheel needs to follow the front wheel on the same centreline..., Or am i wrong????"

Of course you are right, and to achieve this, as mentioned many times in many places, the rear rim needs to be offset to the
right of the hub about 3/16" , of course this assuming your frame etc is straight.

madass140 said:

"When all is said and done. IMO.... The rear wheel needs to be aligned with the front wheel (which is central to forks, which is central to frame) The relationship of rear wheel to frame and swingarm is irrelivant.. The rear wheel needs to follow the front wheel on the same centreline..., Or am i wrong????"

Of course you are right, and to achieve this, as mentioned many times in many places, the rear rim needs to be offset to the
right of the hub about 3/16" , of course this assuming your frame etc is straight.

Click to expand...

Yep i agree with ABOUT 3/16", but chasing 1/64" on a welded steel rim, IMO is fanciful............ (a machined billet rim, well thats different)

Well folks, I have installed the "new" swingarm from Manx Motors and the tire and sprocket have come over. The sprocket now aligns somewhat, but still need to offset the rim to bring it in line with the frame. Thanks for all your help everyone!