On my last ride I noticed a terrible brake squeal. It’s only noticeable up to around 50% brake force, then it disappears.
After the ride I took out the pads and noticed this very weird wear pattern
What is the cause of this?
How do I fix it?
Brakes are Shimano Ultegra 8000 flat mount. Thanks for your help!
by abwaerts
18 Comments
I’m not sure the root cause but everything needs to be replaced
I don’t think those are ultegra rotors. Is it possible you used metallic pads on a rotors only designed for organic?
I think that may be the result of those rotors but I do not recognize the model, so I can’t say for sure. You’d probably be best off with new pads and a different set of rotors as well (Edit: Galfer Road Wave Discs)
Edit: I recommend measuring your disc thickness, this odd wear pattern may be due to the disc wearing past its useful thickness. Once a disc gets too thin, it can becoming locally warped and create uneven wear.
it probably the disc chewing up your pads.. original shimano discs are alot more solid material for the pads to grip. You might get better results with metallic pads than organic, but this type of open disc type really does a number on pads
What are these rotors? Are they matching Shimano parts? It looks like the rotors wore out prematurely and the pads wore to follow, I would not expect that from shimano rotors.
Are your brake pads making enough surface contact with your rotors? (those are not Ultegra Rotors). It looks like your pads are only touching your rotor at the very top of it. It lines up with only the tips of your pads being worn. If you’re using the correct size rotor, and you have the right size caliper mount, then you may have an extra set of spacers on your Caliper Mount.
Is the caliper sitting too high off the pads?
Issue is due to rotor, I recommend to change to anything else but that
I don’t have a lot of experience with rotors but maybe some debris got stuck in between the pad and rotor?
The wear on the pads is very strange as there are almost like channels wear it wore unevenly and the rotor wear kind of matches. My best bet is they weren’t ever bed in properly and the uneven wear just got worse with time. That may have been caused by it not being a shimano rotor, I’d recommend replacing both with real shimano parts and see if you get the same thing after properly bedding in.
Are the rotors completely straight? If you removed them and put them down flat on a flat surface, would they rock/wobble at all?
The wear looks normal foe that type of rotors.
Looks like that rotor is basically chewing your pads apart, the wear pattern matches what happens when the braking surface gets gouged or warped unevenly. Swap both at the same time, putting fresh pads into a damaged rotor just wastes them. Galfer or Swissstop rotors tend to play nice with shimano calipers and run way quieter too.
I’m thinking the caliper is too high, leading the pistons to press the pads at an angle causing the uneven wear on the pads. The rotor also looks like the pads weren’t using the full brake surface. I would want to see the brake adapter setup, it could be upside down. The pads being pressed unevenly on the rotor could also lead to overheating the rotor/pads in that area causing the glazing effect on the rotor.
If your caliper isn’t aligned with the brake pads, this is what happens:
When you brake, the pistons won’t close evenly, causing one pad to hit the disc first and bend it until the second pad makes contact with the disc.
The disc gets torqued and hot, and that’s when the disc brake edges grind the pads. Called premature wear same applies for cars or any vehicle that uses the same brake system.
I’m not a bike mechanic but I have rode and lived enough to pass my experience to anyone.
Uneven caliper piston extension, plus a 200mm rotor instead of 203 maybe?
pads look new did you just replace the pads recently? and if so was that all you replaced? or did this issue just come out of nowhere. We need more context in order to understand the cause.
Can you provide a picture of how the rotor passes trough the break? I have a suspicion that there is something wrong about that.