Whenever you do a wheel conversion on your motorcycle there are three things to be mindful of when considering alignments:
1.) Centering the rear wheel in the frame
2.) Aligning the rear wheel with the front wheel
3.) Chain Alignment
As a general rule you proceed in the order mentioned. This thread is about step #1
1.) Get the rear wheel centered in the frame
for a GS this is simple;the GS swing arms are centered in the frame so center the wheel in the swing arm; the distance between the inside of the swing arm fork to a reference point on the wheel (like the lip of the wheel) should be the same on both sides. Another simple way is to put a straight edge across the tire and measure the distance to the inside of the swing arm. To do this measurement make sure that the rear axle is parallel with the swing arm bolt (measure distance between the ends of the bolts and make sure they are the same on both sides; the swing arm markings could be used as well).
So how is it best to make these measurements? I finally realized that an alignment very similar to the string method should also work on the wheel alignment as well. It is simple and unambiguous.
There are so many variables and people seldom have the exact same configuration that it is best to recommend doing a final check of measurements regardless of how you do the spacers.
You need to put a straight edge against each side of a bare wheel and project the wheel edges forward to the wing arm bolt. In order to measure the wheel to frame alignment you also need to clamp a reference to the swing arm bolt location also. Here is a simplified diagram with some pictures to follow.
Measuring offset between the wheel and the inside of the fork
Measuring offset between the wheel and the frame
You could probably also use a string method to project the sides of the rim forward, but the same measurements would apply. Use the rear wheel alignment marks to make sure the wheel is true in the swing arm. This should be of sufficient accuracy to ensure that the spacers are sized correctly and that the wheel is properly centered in the frame.
A couple of points to make:
A. ) The wheel should always be centered into the frame (as a guide use a tolerance of +/- 4mm max )
B.) The wheel should be offset in the forks by a measured offset of the swingarm forks.
C.)Use the above measurements to check your wheel spacer selections. Continue on with the Wheel and chain alignments after you are done.
Further references here:
http://www.thegsresources.com/_forum/showthread.php?t=147705
I'm an engineer learning how to do this in the backyard. I have had extensive discussions with Katman as well. For further reference Tone is an expert at chassis modifications and has done this professionally. Here is a link to Tone's alignment overview.
http://www.thegsresources.com/_forum/showpost.php?p=1075868&postcount=12
1.) Centering the rear wheel in the frame
2.) Aligning the rear wheel with the front wheel
3.) Chain Alignment
As a general rule you proceed in the order mentioned. This thread is about step #1
1.) Get the rear wheel centered in the frame
for a GS this is simple;the GS swing arms are centered in the frame so center the wheel in the swing arm; the distance between the inside of the swing arm fork to a reference point on the wheel (like the lip of the wheel) should be the same on both sides. Another simple way is to put a straight edge across the tire and measure the distance to the inside of the swing arm. To do this measurement make sure that the rear axle is parallel with the swing arm bolt (measure distance between the ends of the bolts and make sure they are the same on both sides; the swing arm markings could be used as well).
So how is it best to make these measurements? I finally realized that an alignment very similar to the string method should also work on the wheel alignment as well. It is simple and unambiguous.
There are so many variables and people seldom have the exact same configuration that it is best to recommend doing a final check of measurements regardless of how you do the spacers.
You need to put a straight edge against each side of a bare wheel and project the wheel edges forward to the wing arm bolt. In order to measure the wheel to frame alignment you also need to clamp a reference to the swing arm bolt location also. Here is a simplified diagram with some pictures to follow.
Measuring offset between the wheel and the inside of the fork
Measuring offset between the wheel and the frame
You could probably also use a string method to project the sides of the rim forward, but the same measurements would apply. Use the rear wheel alignment marks to make sure the wheel is true in the swing arm. This should be of sufficient accuracy to ensure that the spacers are sized correctly and that the wheel is properly centered in the frame.
A couple of points to make:
A. ) The wheel should always be centered into the frame (as a guide use a tolerance of +/- 4mm max )
B.) The wheel should be offset in the forks by a measured offset of the swingarm forks.
C.)Use the above measurements to check your wheel spacer selections. Continue on with the Wheel and chain alignments after you are done.
Further references here:
http://www.thegsresources.com/_forum/showthread.php?t=147705
I'm an engineer learning how to do this in the backyard. I have had extensive discussions with Katman as well. For further reference Tone is an expert at chassis modifications and has done this professionally. Here is a link to Tone's alignment overview.
http://www.thegsresources.com/_forum/showpost.php?p=1075868&postcount=12
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