twisted frame/swingarm saga??

[Rick]

Here is what I would do:

1. I'd pull the subframe off and all the platic, pipe, tank and skid plate.

2. Get the frame down to bare bones.

3. Then I would start inspecting the frame from steering stem to swingarm.

4. I'd be looking in the weld area's of the frame, every joint where the frame is welded together. I'd be looking for bubbled, chiped, flaking paint, or nickel if the bike had nickel coating. If there are any cracks in the weld area, you might be able to detect by the loose coating. I would really check the craddle really good, you may have broke something loose under there.

5. Steering stem bearing and stem, then I'd have a really good look at the triple clamps for cracks, on the underside where the stem is pressed into the lower clamp.

6. Is the motor tight???

7. You might be able to also snap a chalk line for 30 feet or so, then roll the bike straight down the line and see if it "crabs" / \ to one side or the other. 7 may answer question 8??


8. Put the bike on a center stand, pull off both tires, run a string down the center line of the rims, from front to rear, then get a string level and see if the center of the rims are in line with each other?

9. Check rear brake pads, see if the front or the rear part of the brake pad is wearing properly? Same with the rear sprocket?


I am just thinking out loud here....asking a lot of questions, plus the time involved with this. But I you'll never know what you'll find.....

Good Luck!

[GMP]

It does look a bit odd, but maybe because we are trying to see something. If anything, the swingarm looks to be tweaked left a hair. Do as Eric said, plus you should be able to measure exact dimmensions from each side of both the axel and swingarm pivot to a fixed point on the steering head. Removing the plastic and tank should make it eaiser.

[MattR]

Eric & Glenn both gave you ideas on a datum to measure from. Here are some other ideas for measurements:

Put the bike on a center/bike stand with the bike sitting as level as possible. Then, measure from the ground up to the rear wheel axle on each side. Using the ground as a datum, you will see if there are height differences up to the rear axle. This may help you to detect if the swingarm is twisted.

Another approach:
Use a large "right triangle" (for wood working) and use it to get the front wheel relative to ground perfectly vertical. Then, line up the triangle to the rear wheel. If the rear wheel is off-vertical then it is twisted/inclined.

Since the relationship from front wheel to rear wheel are at the farthest points on the bike, any misalignment would be exaggerated and easier to measure at these locations. The approaches mentioned above are crude but something do-able in the home garage.

[blitz11]

I'll throw in my $0.02 for free. How's that for a deal?

My thought would be to isolate the bike on a stand, and remove both wheels. Using a digital level, have someone hold the front wheel straight, and measure the front axle. (Actually, use the front axle as "zero.") Then, measure the rear axle's roll angle wrt the front axle. This will indicate relative "twist" between the two.

We use a digital level at work to level laser scanners, and it's a pretty effective tool.