Triumphrat

dealsgapdragon · 09-30-2009, 11:08 PM

Motorcycle suspension alignment using strings, trammell bars and laser beam.

youtube.com/watch?v=HcQW_u2AZM8

BombFactory · 10-04-2009, 04:25 PM

I don't think many of these tools shown in the video are accurate methods of measuring chassis/wheel alignment.

The plumb-bob methods proves nothing regarding wheel alignment, as it is totally dependent on the subframe alignment--whether or not the wheel is plumb. There is factory slop in the subframe mounting holes, and a 1/32" discrepancy between the right and left sides at the mounting holes will come out much larger at the back of the tail fairing where the plumb-bob is attached.

The trammel bar method is a good one, but not when using what appears to be pieces of screen door aluminum; these are probably the least likely pieces of metal to be straight. Using 1" x 2" rectangular tubing or, even better, proper straight edge steel or quality 8' levels would be much more accurate.

The string method is a good one, and it shows in the video that there is a 17/32" right offset (with a 1/32 discrepancy on the left side of the front wheel which could always be a wave in the wheel's lip). However, the plywood methods look unreliable at best. For instance, there is an almost perfect 17/32" offset to the right according to the string line method; however, when the piece of plywood is held up against the right side of the front tire and a laser beam is shot from the rear, the laser beam is one-hash mark to the right of the third parallel line on the plywood towards the back of the bike (I don't know if these are 1/8" or 1/4" hashes), but then the laser beam intersects the third parallel line towards the front. This cannot mathematically happen if there is an even 17/32" right offset, which proves that their is either fault in the method of measuring or in the measuring tools.

Alignment measurements are about consistency and require proper, straight tools. I don't see very consistent measurements between the different methods shown in the video--nor is there apparent control in the points of measurement--so I'm not sure why these should be regarded as accurate tools that others can use to measure their alignment when they cannot properly measure the alignment in the video.