Rail (625Wh) howling brakes like a shrieking banshee

Bongles Grandad

Bongles Grandad

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hi,

my Brakes sound terrible. i have taken the pads out, cleaned them, lightly sanded them down and cleaned them again, put them back and i'm still getting the noise. i looked on you tube and tried to get some tips and repeated the process but also gave the disc rota a light sanding. cleaned everything thoroughly and put it all back together and still have the horrendous squealing :(
any suggestions from you guys?
 
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Are they SRAM? Take off and throw in the bin.
Are they Shimano? Align properly and get less squealing. then throw in the bin if it doesn't stop.
Are they Magura? No squealing, it must be your mates SRAM/Shimano.
Are they HOPE? Don't be silly, people don't complain but tell you how good the customer service is?????
 
Bongles Grandad said:
hi,

my Brakes sound terrible. i have taken the pads out, cleaned them, lightly sanded them down and cleaned them again, put them back and i'm still getting the noise. i looked on you tube and tried to get some tips and repeated the process but also gave the disc rota a light sanding. cleaned everything thoroughly and put it all back together and still have the horrendous squealing :(
any suggestions from you guys?
Click to expand...
I have tried….Cable Tie the brake lever on full pressure (not back yo the bar but sensible pressure) and leave over night. In the morning check for fluid escaping from the seals in the caliper and leaking into the pads .

Take the discs off and thoroughly rinse them with brake cleaner on the disc avoid painted carriers with Brake cleaner in case it takes any paint of finish off. Fit new pads.

But I find this is all good until you ride In the wet or through a ford until they dry out and or they are rinsed with water as they collect a slurry (Shimano resin set up here)
 
Yeah the pads that came with my SRAM G2 brakes were so so loud. Almost any 3rd party pads are better. I tend to use Uber resin or their hybrid pads instead.
 
flip bike upside down every few rides
use a dedicated disc brake cleaner like clean streak or just isopropyl and clean rotors
spray on pads and use paper towel to get up in between pads
find a less expensive replacement for oem pads so you don't hang onto the originals too long
 
I’ve battled With Shimano pads for a long time
Thing is, when they’re freshly cleaned and bedded in, their exceptional but quickly lose their bite, on removal always found heavily glazed
I found, removal sand and clean with brake cleaner, clean the rotor with several cloths until spotless
Then bed them in again, though realistically only last several rides
Ive a set of Magura to replace and do hope I don’t have the same troubles
 
Full disclosure, I use magura performance brake pads(4 piston) with the magura 203mm and 220mm MDR-P 6 bolt rotors. I also use the recommended magura mineral oil(blue). Do they make noise? Yup, when I introduce another compound such as water or other contaminants.

Water is unavoidable, but it will quickly evaporate when my brakes are applied and heat is generated. The noise lasts for a moment. Brake fluid is another contaminant. Pressurized brake cleaner can have contaminants in it but the pressurized spray can have some advantages. ISO alcohol here, unless I’m doing a thorough cleaning (with aerosol brake cleaner)on my calliper only, not the rotor and definitely not the pads. If you feel the need to sand the pads or rotor, clean with ISO and re-embed again.

Sometimes it seems like there’s a science when it comes to brakes. Why do brakes need imbedding? Different pad compounds. Which one is better for my riding style? Can I mix’n match? Can I microscopically clean the rotor to remove previous compounds or contamination? Will brake pad ‘A’ work with rotor’B’?

The combinations and suggestions can be endless. Try and “STOP” that!😉
6388778D-F6D3-467D-AE83-EE967B3786F5.jpeg
 
I once had a howling brake problem, rear only, Kona Dawg Supreme. It sounded like a car horn coming down the mountain, and the whole bike was shaking. I certainly was noticed! I tried EVERYTHING. By everything, I mean all I could think of, all the MBR Forum could think of and all I could find elsewhere on the internet, three different bike shops (two in UK, one in France), I even spoke to the Kona technical specialist and he couldn't think of anything else to try, short of replacing bit by bit until the problem stopped, or didn't...
Finally, I swapped the entire rear brake system between my two bikes. The problem stayed with the bike!!! That was weird. :unsure:

I stripped down the noisy bike and sold it off in parts, then I bought a new bike.
 
ive just put new pads, bedded them in and silent for about 5 minutes, then went for a ride and it was back again. took the pads out and there was a ring of moisture on the back of the pads where the pistons are so that must be my problem... will have to take it to the lbs as that is beyond my limited capabilities :(
 
It really does not matter what brand of brake you use or indeed what pads ( given there is a difference between sintered and resin..........but I would assume most on an EMTB doing gravity riding would want sintered), you will get brake squeal if the pads do not interface to the rotor properly........or ( momentarilly) if you get the rotor/pads wet, until heat vapourises that moisture. The noise is a high frequency resonance of the rotor caused by vibration.
So what makes for a poor interface?
Incorrectly aligned calliper ( vertical or horizontal)
Loose rotor
Contamination on pads and/or rotor ( cleaning products/ road or exhaust oils if you use a tow ball rack/ handling the rotor)
Using the wrong type of pad material for the rotor ( e.g some rotors are resin pads only)
Not bedding in new pads
Changing pad type without removing previous pad deposition on rotor
Fluid leak

Of course you could just announce that XYZ brand is rubbish and spend £100s on a complete new set of brakes.............and amazingly (no sh*t sherlock) the noise is cured:ROFLMAO:
 
Bongles Grandad said:
ive just put new pads, bedded them in and silent for about 5 minutes, then went for a ride and it was back again. took the pads out and there was a ring of moisture on the back of the pads where the pistons are so that must be my problem... will have to take it to the lbs as that is beyond my limited capabilities :(
Click to expand...

Leaky piston seal? Contaminated pads could start to make that noise. If that’s the case those pads are toast. Have them remove and thoroughly clean the rotor, after they fix/replace the calliper.
 
Stihldog said:
Leaky piston seal? Contaminated pads could start to make that noise. If that’s the case those pads are toast. Have them remove and thoroughly clean the rotor, after they fix/replace the calliper.
Click to expand...
its at the LBS now so fingers crossed i will get it back later. typical.... its lovely sunny day today and i'm itching to get out.
 
Happy you found the problem. I had the same problem on my Rail 7. Funny how it always seems to be the rear brake, isn’t it. Oil was leaking very slowly at the connection between the hose and the caliper, making it’s way onto the pads. Took me a while to figure it out because of how small the leak was. I had to cut the hose and reattach it properly to its mounting bolt. Unfortunately those contaminated pads also contaminated the rotor. Some suggest it would then be wrecked and have to be replaced. Before doing that i decided to give it a deep clean and see what happens. I proceeded to first wipe them with a good dose isopropyl alcohol, then sand them with 220 grit wet sandpaper, and finish off with another isopropyl cleaning. I then bedded in the new pads. Worked very well, they’ve been quiet since and are as sharp as new. I did find this interesting video that explains why, how and what happens when you bed in your brakes.


The brake calipers on my Rail 7 are shimano 6120 4 pistons

Happy trails!
 
steve_sordy said:
I once had a howling brake problem, rear only, Kona Dawg Supreme. It sounded like a car horn coming down the mountain, and the whole bike was shaking. I certainly was noticed! I tried EVERYTHING. By everything, I mean all I could think of, all the MBR Forum could think of and all I could find elsewhere on the internet, three different bike shops (two in UK, one in France), I even spoke to the Kona technical specialist and he couldn't think of anything else to try, short of replacing bit by bit until the problem stopped, or didn't...
Finally, I swapped the entire rear brake system between my two bikes. The problem stayed with the bike!!! That was weird. :unsure:

I stripped down the noisy bike and sold it off in parts, then I bought a new bike.
Click to expand...
Did you get the caliper mounts faced? Any good bike shop should have a facing tool and the skills to use it… often cures the howling due to resonant vibrations caused by misalignment
 
Wilbur said:
Did you get the caliper mounts faced? Any good bike shop should have a facing tool and the skills to use it… often cures the howling due to resonant vibrations caused by misalignment
Click to expand...
Yes, one of the first things after dealing with all the usual stuff, like contamination for example.
 
Wilbur said:
Did you get the caliper mounts faced? Any good bike shop should have a facing tool and the skills to use it… often cures the howling due to resonant vibrations caused by misalignment
Click to expand...
ill check with the LBS... its still in, they are rammed with work and haven't started it yet :(
 
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