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Brake howling with strong vibration that goes away with heat... stumped

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Yeety

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Discussion starter · #1 ·
Recently installed new M8120 brakes with TRP 2.3mm rotors. N04C metallic pads. For some reason front brake has the dreaded howl when braking gently [read: normal braking]. Strong vibration through the front end accompanies the howl - you feel the noise through the handle bar. There is no perceptible issue with power (this thing wants to lock up the front wheel on asphalt braking from 30) and the howling and vibration seems to go away with heat. Repeated heavy braking from high speed on asphalt cures the issue for a time until the system cools off (couple minutes), and then it's back.

Pads look OK and it doesn't feel like a contamination issue given that this thing still has insane stopping power.

The front brake is mated to a 223mm disc. The rear is the same configuration mated to a 203mm disc and has no such issues.

Any ideas? I'm stumped.
 
#2 ·
Humidity. It’s the time of year.
Mine does something similar this time of year (though not as severe as your situation, I believe) but my squeal disappears during dryer, warmer months.
=sParty
 
#3 ·
I get the squeal with dust as well. Also, even a minute amount of contamination will cause howling. Try switching pads (front to rear) and torching the rotors to see if it helps. Make sure rotor bolts or centerlock are tight.
 
Discussion starter · #5 ·
Thanks for the responses. Everything is tight and centered. I threw in a set of N03A resin pads and all problems went away. So, it's something to do with how the metallic pads grab the rotor. I'll have to do some more experimenting with the known-good rear metallic pads to see if I can narrow it down.

You know how you can make your brake rotor honk/make noise by rubbing both sides with a wet paper towel at once? I think it is a similar expression of resonant frequencies happening here... just the interaction between these specific pads and the rotor material/shape.
 
#11 ·
Yeety said:
Yeah, for now. But the mystery remains why there is no sound from the rear brake with metallic pads and a TRP 203mm rotor. No chance to experiment yet.
Click to expand...
I have this same problem. I have been through three complete sets of SLX front brakes with new shimano and sram rotors, metallic pads, plus cleaning/sanding a few times, on two different forks. I cannot get the front end to stop shuddering howling after few seconds of hard braking. The rear has been completely fine and until now I have never had an issue with shimano brakes making noise.

Baffled
 
#14 ·
The reason for these issues is frequency of vibration, when your pads, rotor, frame all vibrates at the same frequency, it's going to amplify and resonate. You basically have the Tacoma Narrow's bridge going on there. In the automotive world they have to "change something" when this happens, like one of my cars had counter-weights on the disc-brake pads from the factory, to change the frequency. Kia has this problem on the Stinger with the brembo brakes and won't admit it, so they warp the OEM rotors every few thousand miles. Most people switch to aftermarket pads or rotors, which can solve it. The problem with this issue is you don't really know for sure if a changeup will fix it, but if you do change the frequency, you can stop it. I had this real bad with some Avid Codes back in the day. It was absolutely crazy, like it would make the whole bike shake during the vibration to where I couldn't control the bike or hold on. There's no real solution except to try and change the frequency.
 
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#15 ·
I am having this issue and this was the only thread I could find online. It just happens to be the combo- I put back my old magura rotor and no noise. I swapped the TRP front rotor to the rear and the front would howl. I did everything possible from cleaning, sanding to burning. I just picked up some MTX gold pads. Trying to bed them in with some neighborhood laps before the weekend. Hoping this solves the issue but now I am reading people have been glazing these ceramic pads :cry:
 
#16 ·
One or more pistons misaligned or seized and or too far out, pads warn, pads glazed, rotor loose, caliper loose, caliper misaligned causing rotor bedding, rotor warn, rotor backwards, rotor bent

Anyone or combo of those things.
 
#17 ·
recently had similar issues with shimano metal pads & galfer rotors on m8120 XT's. the feeling through the bars sucked.

Not even the Real good shops with Ex race mechanics could figure it out.

metal pads are a pain... some brakes they work flawless like SRAM's offerings
Currently have Mavens on that same bike same rotors with metal pads and the power is so insane it's probably to much.
 
#18 ·
plummet said:
One or more pistons misaligned or seized and or too far out, pads warn, pads glazed, rotor loose, caliper loose, caliper misaligned causing rotor bedding, rotor warn, rotor backwards, rotor bent

Anyone or combo of those things.
Click to expand...
I checked all of those and still howled. I literally did everything possible.

MrPotential said:
recently had similar issues with shimano metal pads & galfer rotors on m8120 XT's. the feeling through the bars sucked.

Not even the Real good shops with Ex race mechanics could figure it out.

metal pads are a pain... some brakes they work flawless like SRAM's offerings
Currently have Mavens on that same bike same rotors with metal pads and the power is so insane it's probably to much.
Click to expand...
yeah I think it’s just the combo because I even threw on the old rotors and silent. The wtf moment was swapping the front and rear rotor and the front would still howl.

If these MTX golds howl I’ll be going back to Magura rotors or maybe try the SRAM HS2.

I am also waiting for the new Saints to drop.
 
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