Spinning up
We balanced three Hyper 9 motors on the bench the past week, including yours. The process includes installing the flywheel coupler first (the blue component on the output shaft) then the flywheel and lastly the clutch pressure plate. Runout is checked at every step. Even when quality components are balanced, a tiny bit of runout (thousandths of an inch) can cause vibration. In the original flat 4 that’s no big deal, but with a smooth electric motor, it can be noticeable. So the balancing process is key.
In a neat example of futuristic tech, we use an accelerometer to test vibration. When they identify the RPM ranges that are the worst, they take a baseline measurement. They add weights (washers) to a bolt or two on the pressure plate, carefully observing for improvement or worsening of the vibration. The motor and separate components are likely balanced by their manufacturers but this is the first time the assembly together is balanced. It’s amazing that the weight of a couple washers can have a huge effect.
You can see how the vibration improves based on the screenshots below. We typically get an 80-90% reduction in vibration with only 2-3 washers placed in very specific locations.
