Tech Tips

Hydraulic Brake Rotor Replacement

Written by  April 30, 2008

Spring has officially started, but you would never know it judging from the weather in the Midwest. It seems like we are entering another Ice Age. During the course of the long winter months, I have been busy repairing motorcycles that have been in dire need of some extreme makeovers and love. One thing that caught my eye was the brake rotors on a bike that recently visited my lab just a week ago. When you start hearing a metal grinding sound and you start feeling an erratic pulsating in the braking system of your motorcycle, it is time to have it looked at. The main reason is because it is not safe. I have been always told that the customer is always right. Well not true! When it comes to the safety of my end users, I always step up and suggest safety first no matter what the cost! Motorcycle brake systems and brake bleeding have been covered in this column before; however, I have not covered the actual replacement of the rotors to date.

When you decide to have your motorcycle looked at, here are the steps that must be done to remove the old rotor and replace with a known good part.

Locate the cause of the failure.
Lift your motorcycle off the ground using a jack, lift or equivalent.
Remove the wheel.
Use the correct tool to remove the rotor mounting bolts.
Rough up the brake disc with sandpaper, emery cloth, or replace it.
If replacement is necessary, add Loctite to the rotor bolts and torque to manual specs.
Reinstall the wheel and brake calipers and then torque axle shaft to specs.
Spin wheel for proper alignment.


Some of those weird noises that just make you cringe when you apply the brakes on the road can be as simple as a brake pad that has been worn down past the service limit that has started to rub against the metal backing of the pad. There are a lot of different items that could be the culprit; however, determining the problem requires not just a visual inspection as there also may be some road debris that has gotten lodged into the brake material and pads, and this will prematurely wear out the pads. This is not really a difficult tech tip if followed correctly. Really taking the time to look over the brake pads and rotors will not only give you a different perspective when it comes to the brakes, it will also keep you safe and sound on the road. When you need to really dive on the brakes, you will get the full braking force that the manufacturer has designed. When it comes to the brake rotors, these are very expensive, and if they need to be replaced prepare to pay a minimum of $200 and up, and when it comes to the chromed Harley rotors these are REALLY expensive, but the same inspection and replacement procedure applies to these too!

When you are getting your bike out on the roads this spring be careful because the streets are still sandy from the winter and corners can be very unstable!

B-safe out there!

Dave Miller