When performing a brake inspection, checking brake rotors should be included in your inspection points. I added a quick auto repair video at the bottom that walks you through the process. Special attention should be dedicated to each rotor when a driver complains about things such as pulsation, vibration or brake noise.
Brake pulsation or a surge felt in the brake pedal when the vehicle is slowing down with the brakes applied is a very common complaint. Most often this can be caused by excessive lateral run out or a wobbling of the rotor from side to side as it rotates.
This can cause the brake pedal to pulsate, push back or vibrate during all kinds of braking. On older style disc brake rotors it may be possible to resurface the parts. On newer vehicles with a composite type they are usually much thinner and if they are able to be resurfaced at all there is a limit to how far you can go.
In some cases scoring can be caused by linings that are worn through to the rivets on the backing plate. It can also be caused by friction material that is of poor quality. Road debris or even rust can also work its way between the friction material and the rotor disk itself causing grooving and scoring.
If you were planning to just hang new pads but find a rotor exhibiting heavy scoring, they should be replaced or resurfaced to provide the maximum life out of the replacement friction pads. Heat scoring looks a little different than what is described above. Excessive heat can cause the surface to be charred or even a bluish purple color.
It can also cause an extremely shiny glaze that can cause not only brake noise but increase stopping distances. With extreme heat scoring sometimes little cracks can be seen on the friction surface.
This is known as heat checking and it's recommended to replace the rotor when this is detected. Rusty parts are another thing to look for when checking brake rotors especially if the vehicle has not been driven for a long period of time. If there is excessive rust on the surface of the rotor it can act like sandpaper in between the friction pads and the face of the rotor. This can result in excessive wear and scoring as mentioned above.
After carefully inspecting them you then have to decide whether you are going to resurface or replace them. In my opinion it is the thickness of the rotor that is the most important thing to be considered.
The minimum thickness of the rotor is stamped on the inside hub. This means measuring the current size of the rotor should be performed before making this decision. Unfortunately you will need a specialized measuring device to get an accurate measurement.
Another thing I think should be considered when trying to decide whether to replace parts is the costs involved. In my area of the Country resurfacing a rotor costs about $14-$20 for each disc.
Most auto parts stores will perform this service for you. It's a good idea to check the price of the replacement rotor because often a new part is not much more money. This again will depend on the year, make and model as some brake rotors can be very expensive.
My opinion on this subject is I would rather pay a few extra dollars for a new replacement part. The main reason I feel this way is that after going to my local parts store and having several rotors resurfaced sometimes they did a poor job.
A rotor is installed on a lathe
and the metal is actually shaved away to provide a new surface. There is
some skill involved in performing this operation properly. If your
parts store doesn't know what they are doing you could be in for a long
Bookmark this disc brakes page or share with people having brake problems such as noise and brake pulsation.
I have some more information on checking brake rotors that includes additional videos and in depth articles about car disc brakes.
Would like to see an auto repair video that shows what’s involved in a DIY brake service? This next link takes you to the brake job video.
If you would like to get a rundown of the available information on the you fix cars website this next link takes you to the homepage from this page about checking brake rotors.