Please help, brakes glazing no matter what
No matter what I do, I cannot get my brakes to bed in properly on my rear brake (ultra caliper and rotor, ice tech pads). As you can see they glaze with the same pattern, and it doesn't matter which pads I use I get the same. They have limited bite, and squeal under gentle brake pressure.
I have tried all combinations of sanding and Fenwick disc brake cleaner on the pads, on the rotors, checking for leaks on the caliper, bedding in with x10 – x15 slow gradual stops. The picture is the 3rd pair ive failed to get bedded, and are brand new out of the box.
When testing the pads they will glaze like this after 2 or 3 gentle stops from 10mph down to 2mph.
by murdocsvan
12 Comments
Squirt water from a water bottle on the caliper and rotor during break in. The squeal will be horrific for a little while but keep doing it until the brakes are dry. Repeat this several times until bedded in. Usually takes between 20-30 minutes
“Slow gradual stops”. I think both SRAM and Shimano say 10-15 progressively faster, harder stops but not full stops.
I do have a problem with the front on a Shimano 105 calliper. Did all the things I usually do. Even replaced the calliper. I eventually discovered that the pucks retract very slowly on both callipers causing the front to glaze. Next step is the next generation of 105 calliper.
Remove disc and do a deep decontamination. Might be some residual oil stuck in the vents.
Give up on those pads and get a new set. Resin pads are near impossible to decontaminate once they get oil on them.
Triple check caliper isn’t leaking.
New pads in, clean rotor on, try bedding in again.
I have found lightly sanding the pads face down, with alcohol and heat works the best for new or glazed brakes.
Clean The brake pads and rotors with isopropyl alcohol
I would sand the rotors lightly with 180-220 grit sandpaper to give them some texture. Then clean well with isopropyl, then try to bed pads again. Obviously sand the pads down first.
Have you measured your rotor wear? They’ll never wear completely flat and normally will wear concave as in the center wears first. It’s possible you just have roached rotors which can absolutely happen within 2000 miles if you’re heavy on the brakes and especially if you live in a dusty environment.
I’ve been there. I bought pads, glazed them, sanded them, every time meticulously cleaning everything around the break – to no avail. In the end it turned out the rotor that I had cleaned a thousand times with what feels like galons of isopropyl and silicone remover.
As soon as I switched out the rotor and the pads – silence and no more glazing.
Working in shops for so long I finally gave up all the cleaning, sanding and spraying/praying pads and rotors. 99% of the time fire works. The 1% just needs it done again.
I think it’s worth having a bernzomatic torch around anyways.
Sand pads until uniform and clean, then burn with torch slowly. You are not overheating them but you should see smoke. Too much heat will degrade them, too much heat can actually cause pads to explode if they are overly wet and heated too quickly. Point pads away from you.
Rotors get burnt as well. Do it on or off the bike whatever you feel confident in. You should see a thin film burn away. Again you are not getting things red hot and altering the properties of these metals.
I have no affiliation or opinions on GCN but it seems like they have a video on the same topic if that may give you more confidence. Good luck!
I’ve found barkeeper’s friend to be the best thing for cleaning rotors. Fine abrasive gets in the grooves without removing too much material. Oxalic acid is very aggressive on oxidation/corrosion but very gentle on the base metal.
for me shimano calipers leak always🤷 i bought some IIIpro ones they have a monoblock design. no squel even after a rainy ride and the pads are dry again. gl
I suspect you may have had a leak of some sort onto the disc, what caliper is?
Shimano? Use break disc cleaner, light sanding with sandpaper, clean again, try new pads then.
If it happens again, you more thank likely have leak at the caliper or are getting some dirt on it. Do you transport on a bike carrier that has sooty exhaust onto the brake disc? Had this happened to me before when the car engine messed up, overly sooty