Take a look at this closeup diagram of the rear suspension and brakes of a Honda CB500/550 four. Notice anything? It's the placement of the rubber washer. It's outboard of the torque arm in this picture, not inboard as many folks like to put it. "What good would it be doing there?", you are probably asking. Well, that depends on what it's there for, doesn't it? The fact is, it's not a cushion for the torque arm. Putting it between the brake panel and the arm is not only incorrect, it actually makes the bike unsafe because it prevents the bolt from tightening correctly. Where Honda put it the part damps resonance that might add to brake squeal. Yup. It's a sound deadener, just like the rubber sleeve on the carburetor throttle return spring. So put it in the right place.

This is not how the washer goes. Compare this with the orientation above. This picture is from the sohc4.net forum. That bolt's threads don't look too good. Guess polishing is more important. Interestingly, the East Indian and Chinese copies of popular Honda models make this same mistake from their factories.