Brake Shudder Explained and How to Fix It
Sep. 21, 2016
Brake shudder… You may have experienced it while driving, but what is it exactly? Brake shudder is the vibration that you feel through the steering wheel when you hit the brakes. Brake shudder arises as a result of issues with the brake discs. Namely, when the brake discs have been affected by Disc Thickness Variation (DTV). This refers to the uneven wear of brake discs and is the result of rotor run out.
If your brake discs are unevenly worn the brake pads come in contact with the flat spots present in the rotor’s surface which causes the vibration that we call brake shudder. This kind of uneven wear to the discs can be the result of a number of things. For instance, the brake calipers not operating correctly, the rotors not having been installed properly or the proper bedding-in process not having been applied if new brake pads have been installed.
How do we remedy brake shudder if it becomes apparent? First thing’s first, the source of the issue needs to be isolated. Generally, when shudder is felt through the steering wheel this indicates that it’s the front rotors that need to be looked at. If a shuddering pulsation is felt through the brake pedal, this usually points towards an issue with the rear brake rotors.
How do we remedy brake shudder?
If a brake disc develops DTV, the disc needs to either be machined to iron out the flat spots or replaced completely depending on the condition of the disc. Brake calipers that aren’t working the way that they’re supposed to can also contribute to brake shudder. If a caliper is holding the pad against the disc when the brakes aren’t applied this can lead to the disc wearing unevenly. If this is the case, seized slide pins in the caliper are usually the culprit. Simply take them out and regrease them with Bendix Ceramic High Performance Synthetic Lubricant. Otherwise, if the issue goes further than the slide pins, the calipers may need to be rebuilt or replaced.
Another common source of brake shudder issues is an uneven mounting surface on the face of the hub.
Uneven rust and scale deposits can build up onto the hub face over time, which in turn creates an uneven surface for the disc to be mounted on. If this is evident, clean the area with some sandpaper and WD40 until the rust and scale is gone.
This should be common practice when replacing or refitting brake discs to help prevent any instances of brake shudder in the future.
When installing a new set of brake pads, it’s important to bed them in properly. Subjecting your new brakes to abuse without having followed any kind of bedding-in process can lead to extreme thermal shock which can be a major cause of uneven wear. However, if the Bendix brake pads you’ve selected have our unique Blue Titanium Stripe, the bedding-in process is not required. Also, a small detail but one worth paying attention to is your wheel nuts. Torquing down your wheel nuts evenly and to manufacturer specification using a quality torque wrench can help prevent rotor run out.
When it comes to your brakes it’s important to keep them in top notch condition. After all, they’re the only thing slowing you down.