Brake SQUEEL...HELP!

[simplemind]

Okay, I know this isn't WW per se, however I'm at my wit's end. I have the Shimano DI2 brakes with new 140mm Freeza rotors. The rear brake refuses to behave, with a loud howl as I slow down. I have tried 1) sanding the rotor and pads, 2) replacing the pads (organic), 3) cleaning everything with brake cleaner, 4) calling the bike mfg for any brake noise history, all without success. I installed an old set of metallic pads and while they don't howl until the very end of a stop, they also don't have near as much stopping power. With 140mm rotors, I need the stopping power of the organic pads. Any ideas from here?

[PinaF8]

I have had good luck having the pads in negative camber and a touch of toe in. Good luck!

[MoreRideTime]

Hazarding a guess here I'd suspect that the pads have been contaminated with something. Had this happen on one of my MTBs. After I replaced the pads things were fine. When you do replace the pads, clean the rotor well with isopropyl alcohol (that's what Shimano recommends). Then, be sure to bed in the new pads. Ride around the block and drag the brakes slightly. Do some accelerations and pull hard on the brakes.

Oh, check that there is no mineral oil leaking in the calliper, I've seen a couple of brakes come with poor seals at the pistons and had to have Shimano warranty them.

[PinaF8]

I have had good luck having the pads in negative camber and a touch of toe in. Good luck!

Oops I effed up. Disregard and missed the rotor portion.

[simplemind]

Thanks for the comments...yes DISK!
It's was about alignment (in my case)!
Anyway, switching out the wheels that have the same type/size rotors yielded the same noise, hence more focus on just the caliper. Found a good tutorial on the issue with an emphasis on alignment so my usual way of aligning was possibly the culprit. Normally I will just loosen the two bolts holding the caliper, squeezing the brake lever and while holding the lever, re-tighten the two bolts. Almost always works...almost!
So, here was my new procedure: With the pads out, press the pistons all the way in with a plastic tool (if pads are worn, you may have some spillage at the master cyl.). Then eyeball where the center of the caliper is, in my case it's the joint of the left/right 2 piece housing. With the disc in place, align both top and bottom (loosely tighten bolts until your sure it's aligned) then torque it down. Replace pads and squeeze lever and recheck alignment with pads in place. If one piston is "lazy", then you can use something to press that piston back into the housing. May have to do that several times to get it right.
Right now (fingers crossed) my brake is silent for the first time since I built it up. Evidently, the stars have to align on my particular frame/caliper to make it noise free.

[TonyM]

I have the Shimano Dura Ace disc brakes and rotors SM-RT900S & SS in 160/140mm together with the L02A Resin IceTech brake pads.
They are GREAT and not noisy when dry but noisy when wet. I read somewhere that it seems to be usual with these rotors/ brakes/ brake pads.

[jeanjacques]

"Silent disc brakes (we promise)" by November Bicycles: https://novemberbicycles.com/blogs/blog ... we-promise

[TonyM]

"Silent disc brakes (we promise)" by November Bicycles: https://novemberbicycles.com/blogs/blog ... we-promise

Thanks! [emoji106]
I will give a try for the „grease“ procedure on the back of the pads!

[simplemind]

"Silent disc brakes (we promise)" by November Bicycles: https://novemberbicycles.com/blogs/blog ... we-promise

So many things to go sideways and only one thing to go right. I'm keeping mine in the "grease free zone". BTW, just went on a hilly 25 mi ride, and nary a sound out of the brakes, so I'm going to go out on a limb and declare my issue was just alignment.

Now, this sparked a thought, my issue with grease is migration. However, what if you used a dab of RTV silicon instead....

[silvalis]

On your alignment thing - try jamming a couple of business cards or similar in on either side when you grab the lever and bolt it down. Will help with the eyeballing part.

[SilentDrone]

I have had good luck having the pads in negative camber and a touch of toe in. Good luck!

Oops I effed up. Disregard and missed the rotor portion.

I seriously thought you were trolling him. It made a nice troll post!


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[simplemind]

On your alignment thing - try jamming a couple of business cards or similar in on either side when you grab the lever and bolt it down. Will help with the eyeballing part.

Great idea!

[MoPho]

On your alignment thing - try jamming a couple of business cards or similar in on either side when you grab the lever and bolt it down. Will help with the eyeballing part.

Came to post this, I usually just fold a business card over the rotor


.

[stockae92]

What I did on my MTB was, clean the rotors and pads with alcohol, torque down the rotor and caliper to spec with torque wrench. The noise would mostly go away.

But when I do ride along beach, heading home after sunset, and the air is just a little damp, the disc is NOISY!

[Lewn777]

Rather than two business cards just invest in one of these....

http://www.jensonusa.com/Hayes-Brake-Pad-and-Rotor-Alignment-Tool

Then make sure you have bedded-in the pads properly. I use a mountain road to get the heat into the pads.
http://www.bikeradar.com/gear/article/how-to-bed-in-disc-brake-pads-31337/

If that doesn't work copper grease on the back of the pad, but I never bother, because as has already been mentioned the possibility of contamination.