Eight steps to banish disc brake rub

Banish Disc Brake Rub

A simple way to check if brakes are centred correctly is to look at the pads. They should wear evenly, as the piston should squeeze them squarely against the rotor. It’s worth digging out old pads to check the calliper setup.

Older post and IS mount callipers need to be removed to reset pads. Newer callipers allow you to remove pads without taking off the calliper. Progress! Use a plastic tyre lever to push pads into the calliper without damage.

If you removed the calliper refit it loosely. Look through the back of the calliper or the front to see the gap between each pad against the rotor – it should be equal. Also, if you want to bleed
a bit, now’s the time.

Many post mount callipers use cup and cone spacer washers. They offer just the right amount of wiggle room. They can bind together, so you may need to loosen the bolt and tap the washers for them to move freely.

Most rear mounts are still the IS format, which allow sideways spacing of the adaptor via shims. Ensure your calliper’s range of movement clears the disc before you start trying to align it. If not, add/remove shims to the adaptor.

Tighten one bolt a small amount, then the other, and repeat until the bolts are close to the correct torque settings, checking alignment all the time – the turning of the bolts naturally pulls the calliper out of line, and working gently helps.

Pump the brake lever a few times to return the pads to their natural position. With the calliper aligned, slowly spin the wheel, listening for rub. Slacken the bolts slightly (not all the way) to tweak positioning.

If there are ‘high spots’ that can’t be stopped from rubbing, locate the warped section and slowly/gently bend the rotor back the other way using an adjustable wrench or rotor truing tool. Tweak it, check, tweak it, check. Be patient!