Mattyb13

No matter how many times I try, I continue to have howling from my Force Disc brakes on my SL7 Pro Tarmac. I clean, and bed in properly repeatedly, but they just howl. I am going to try one more brand new Paceline rotor, one more time and one more brand new set of pads. I am curious if anyone has used or recommends other than SRAM brand brake pads? Thx.

PeteHski

Are you using organic or sintered pads? The former are generally quieter. Also what are you cleaning them with?

Mattyb13

I have been using the Organic/black pads. I have been sanding my rotors with 150 grit, and then cleaning them with alcohol. I have heard about acetate working but I have not tried that yet. Also heard of lighting the rotors and pads on fire after cleaning as well. Haven't tried that either. Never touching the rotors or pad surface and always wearing nitrile gloves. Its been really frustrating. I have the rears in a fairly quiet (although not completely quiet) place, but my fronts sound like an air horn.

PeteHski

Strange one this. Okay next question. Is this happening on both your front and rear brakes or just one of them? Trying to rule out things like resonance and alignment issues etc.

Just as an aside, I do literally nothing in the way of cleaning with any of our many disc brake bikes and non of them are noisy. I just bed in the pads and ride.

Bald Paul

Personally, I would be using a much finer grit (minimum 1000.) Auto parts stores have a product called Brake-Kleen designed specifically for cleaning brake pads and rotors. It leaves zero residue. (Hint: don't even THINK about lighting it on fire!)

PeteHski

….and if you are starting with a new rotor and pads then don’t touch them with anything. Just fit them and ride, following the usual bedding in procedure.

Psimet2001 

Sounds like you're just cross polluting everything - meaning you are changing one thing and not another until it's already been messed up.

1. Replace the rotors and pads all around. Full stop. No skimping.
2. Make sure the calipers are tightly mounted.
3. Make sure the rotors are very tightly mounted.
4. Make sure the rotors and pads are matched (resin pads to resin compatible rotors).
5. Bed the whole system in correctly. Get up to speed, drag the brake slightly for a while to warm it up, then apply harder to come to a quick(ish) stop then let go before you come to a complete stop. Repeat 10-20 times. The more the merrier.

If you can't get it to stop with new pads and rotors and after bedding them all in then you have a problem - either with you and your process, the caliper is leaking or you have other mechanical issues with the bike like a loose headset, or just crappy frame and fork. There is absolutely no need to go outside of OEM rotors and pads. In fact I would say you should absolutely insist on staying with OEM pads and rotors. The system will absolutely work flawlessly with OEM pads and rotors. If you can't get it to work that way then I assure you it isn't the pads and rotors.

Psimet2001 

tbh - sanding and cleaning a rotor has never truly worked in my experience. I have done it in mild situations when contamination wasn't most likely an issue but in cases of contamination it will just continue. The fluid is in the pads and can not be cleaned out. It will get on the rotor. You can't get the rotor completely clean and it will transfer to the new pads.

I have cleaned with brake cleaner, all sorts of grits of emery, alcohol, acetone, I have set fire to them, etc. Based on my years of working with all of these systems it's a better use of your time just to start from scratch with the right gear.

Seattle Forrest

My happiest day as the owner of a SRAM Force 22 hydro disc bike was the day I sold it.

Psimet2001 

As a mechanic in the home of SRAM (Chicago) who can name people who helped design those brakes... it pains me to say that I totally understand.

...after having had to pull stuck pistons and master cylinders out of 2 systems in the last week simply because the owners have had them for a few years. Can't stand the fact that I have to do it to my own kid's bike for cross racing this fall.

Mattyb13

This is great advice and I completely agree. I am going to go with all new rotors and pads all the way around, start from scratch and hopefully that fixes this. Good call also on checking the caliper, disc and headset. Stay tuned for updates. thanks.

TiHabanero

Ran into this earlier this year with a front Force disc brake. Tried everything you have already done plus what you are about to do. The only solution was replacing the front wheel with an upgraded model. This worked perfectly and has continued to work perfectly. There was a problem with resonance in the front wheel, and at first it was replaced with an exact same model, but the problem persisted. On a whim we tried an upgraded wheel and bam! it worked!
Outside the box thinking solved the issue.

Racing Dan

In my (admittedly limited) experience all the elaborate "bedding in" schemes and what not to make your brakes not howl or brake better is just deluding yourself. If you keep it clean form oil It either works or it doesn't. Normal use should be plenty to keep the brakes "bedded" and silent. If not, your forever fighting an uphill battle to keep the brakes efficient and silent, in essence chasing your own tail. A different rotor and/or resin pads may alter the outcome, but I'm convinced mindlessly replacing components 1:1 and trying ever more elaborate bedding methods wont.

RNAV

Just curious . . . in the auto industry we put grease on the back side of the pad (between the pad and piston) to prevent brake squeal. I haven't seen that mentioned in this thread. Is that something not done on bicycle disc brake applications?

PeteHski

It is not normally required on bikes. Probably because the pads are so much smaller and the grease would probably find its way onto the wrong side!

blakcloud

It could be an expensive solution but a solution none-the-less. Thanks for sharing this.

Lazyass

After trying every tip and trick I could find on the internet to stop the airhorn sound coming from my 105's and reaching the point where I was about to put the bike up for sale and give up on discs forever, I sanded the rotors out of desperation. They've been silent ever since. I lightly sanded them with a piece of rough grit that came in a tube patch kit, just enough to scuff them up. Worked for me. If you're using a lighter grit it may not be enough.

Bald Paul

Permatex makes a product called "Disc Brake Quiet" that is applied to the back (piston) side of the brake pad. It may help. Just follow instructions.

MoAlpha

Maybe I've been lucky, but I have never had a 30 sec burn-off in a gas flame fail to silence a dirty pad.