Checking the thickness of your brake disc or rotor? It’s a good idea to keep an eye on how they are wearing, particularly if you are using an aggressive brake pad type that causes more rotor wear than the OEM pads. Once the rotors have worn down past a certain point they need to be replaced. Here’s how to check your disc thickness!

If you look at the side of the disc you can see the minimum thickness stamped into it – for the rear rotor used in this example it’s 3mm:

Using a set of digital vernier calipers (eBay US, eBay UK, eBay AU) we can get a reading of the thickness of the rotor:

4.43mm! Great! There’s a catch this time around, though – while it’s not obvious in the photos the brake pads have worn the center part of the rotor down much more than the outside, and the verniers only measure the outer thickness and not the shallower mid-section. For that you need something else – here we are using a micrometer (eBay US, eBay UK, eBay AU):

In this case we can see that it’s ~1mm thinner than the vernier calipers measured it at – though still over 3mm, fortunately.

Are yours below spec or otherwise damaged? Grab a new one online (eBay US, eBay UK, eBay AU).