“If everyone is doing it differently, then we are all doing it wrong,” is the approach that I take when faced with a manufacturing process problem. In order to have consistent outcomes in any process all those doing the work need to be following the same procedure. The following is a straight forward way to consistently measure the swingarm angle and will be known as the “Steve Collins Method of Swingarm Angle Measurement”. For those of you that don’t know, Steve Collins is a seasoned Ducati mechanic and built the custom Ducati that Dave Moss is racing for the 2022 AHRMA season. The key to Steve getting consistent angle measurements is that he gets the suspension on the bike fully extended before taking the measurement. This ensures that the suspension’s stiction doesn’t influence the attitude of the motorcycle and that any adjustment he makes on the swingarm can be measured with good repeatability.
The Steve Collins Method of Swingarm Measurement
There are different ways to get the suspension fully extended but he described it to me as, “the front tire touching the ground (but absolutely no weight on the forks), and the rear tire touching the ground (but absolutely no weight on it)”. The way I achieved this was by using an “under the triple tree” front stand and a scissor jack under the engine. With the front stand, the forks are fully extended but the front tire is at a fixed height above the ground. I cut a piece of wood to a length that barely allowed it to slip under the front tire. I used this piece of wood as a “datum simulator” and raised the rear of the bike with the scissor jack until the piece of wood slipped under the rear tire. I now have the suspension on the motorcycle fully extended and the tires at the same distance off of the garage floor; the motorcycle is now ready for measurement.
PROCEDURE
- Raise the motorcycle so that the suspension is fully extended and that the front and rear tire are the same height off of the ground.
- Zero the digital angle finder on the same floor that the tires are on. (Your reference plane)
- Install the SWINGARM ANGLE TOOL and place the digital angle gauge on it.
- Record the angle.
