Re: Disc brake tuning

On 4/26/2024 9:11 PM, James wrote:

This might have been mentioned, but I'm not about to wade through the endless oceans of shit being posted here to find out.
 Just like with rim brakes, it's important to ensure that disc brake pads are aligned with the braking surface.
 Disc brake pads I've encountered come with a leaf spring that pushes the pads against the pistons to retract the pads when the brake is released.
 The leaf springs don't seem to be well formed from the manufacturer, such that the pads can be resting not squarely on the piston face while the brake is released.
 I've found that by carefully bending the leaf spring it's not difficult to make sure the pads are pushed square against the piston faces, and parallel with the disc.
 Without having done this the brakes can feel spongy, as it takes excessive brake lever movement before the pad has aligned with the disc and the pad is really doing some braking.
 

With new pads, look closely at the pad-rotor space (flashlight, maybe magnifier) from as many angles as possible. Is everything parallel? A pad touching at one end or corner would give that symptom.
If so, slack the caliper mounting bolts, apply the brake and hold it firm to the rotor while tightening the mounting bolts. Check again to ensure that everything is parallel. Some removal of crud may be necessary before aligning the caliper to its mount.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971