|How to Measure Transmission Sprocket Offset||| Print ||
How to Measure Transmission Sprocket Offset
You can measure the precise transmission sprocket offset you need, assuming you have a few things available:
1. Your rear wheel is in place, centered, and straight.
2. The engine and transmission are aligned to each other, and are aligned to the frame
(If these things are not done, please refer to the “Custom Drive Train Alignment Procedure” in our V-Twin Tech/FAQ’s Section)
3. You have a straightedge available that will reach from the rear axle to the transmission output shaft
4. You have a measuring device capable of measuring gaps to .001” (we recommend a dial or electronic caliper here)
Using the rear wheel as a guide, take a look from the rear of the motorcycle forward across the rear wheel hub to the transmission sprocket. Does the rear hub mounting flange extend out far enough for the chain width to clear the tire? If not, use spacer washers to move the drive sprocket away from the hub far enough to allow the chain to clear the tire by a safe margin (.150” Minimum).
Use a straight edge held to the outside face of the drive sprocket to project forward past the transmission output shaft.
Measure from the inside surface of the straight edge to the exposed surface of the output bearing spacer (The metal collar surrounding the transmission drive spline).
Make note of the dimension, and subtract 0.350” to account for the width of the teeth on the sprocket, and you have the required offset to fit your final drive, as well as any shimming dimension required for the rear sprocket to hub fitment.
Sometimes you’ll have to extend the rear sprocket further, and select a greater offset at the transmission to get things sorted out at the rear wheel. Sometimes the frame or swing arm can get in the way.
In the end, you must position the rear sprocket and transmission sprocket within .050” for proper chain operation, the closer to absolute, the better.
Any way you build it, there’s a way. Most frame manufacturers have already sorted out a drive solution for the frame they provide you, and some come with the necessary primary spacer kit and/or extended transmission shaft to get it done. We’re here to help.
Thanks for taking time to read through this. We’d appreciate your input and comments. If you have something you’d like to add, drop us a line by CLICKING HERE