The Friction Wheel is part of the clutch assembly, which helps to drive your unit. If broken from being worn down, you will have drivability problems and should replace the part. This part is metal with a rubber outer ring, and comes in white/black. Installation will require a wrench set, socket set, and pliers and is rated as "Medium" difficulty by customers. Refer to your make, model and diagram to check if this is the right part for you.