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Road disc chat?


donkpow

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So, you know, I've been dealing with this wonky front disc brake on the Surly. The original rotor just did not want to tune up properly. Well, I got it dialed in but the brake squealed. So I deglazed and cleaned the pads and the rotor. Deglazing with some 600 grit emery cloth. Still squeaks. So I did some magic in repositioning the caliper. Still no joy. I can't stand this noise. I avoided the more durable pads so I wouldn't have to live with the metal on metal grinding sound. That may be okay for a down hill mtn bike rider but not me. So what am I going to do?

Last night, while Tom was hiding in his basement, I cleaned and deglazed one of the rotors off the wrecked Cannondale. I created a crosshatch pattern on the rotor with some emery cloth. How you do this. First you clean and deglaze the rotor with some emery cloth. Then you go all the way around the braking surface with your emery cloth in one direction only. Then you go back over the braking surface with the emery cloth going in a 90° direction from the first pass. 

This morning, I cleaned the prepared rotor with some some soap and water and wiped it with alcohol. Clean. Then I pulled the pads again. Deglazed them slightly with some medium grit emery cloth and rinsed them with some alcohol. Swapped out the rotor and installed the replacement using the correct torque pattern. If you don't know, that's an "X" pattern in multiple steps such that the rotor is installed with uniform pressure all around. I don't have a torque wrench for the bike but I'm pretty sure I'm in the ball park. Reinstalled the wheel, checked the caliper position, tuned the rotor and adjusted the pads.

I don't know if this will work. I'll go out into the dry weather tomorrow and bed the brake in. We'll see if this does the trick.

Whatcha got?

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On 4/20/2019 at 11:46 AM, donkpow said:

So, you know, I've been dealing with this wonky front disc brake on the Surly. The original rotor just did not want to tune up properly. Well, I got it dialed in but the brake squealed. So I deglazed and cleaned the pads and the rotor. Deglazing with some 600 grit emery cloth. Still squeaks. So I did some magic in repositioning the caliper. Still no joy. I can't stand this noise. I avoided the more durable pads so I wouldn't have to live with the metal on metal grinding sound. That may be okay for a down hill mtn bike rider but not me. So what am I going to do?

Last night, while Tom was hiding in his basement, I cleaned and deglazed one of the rotors off the wrecked Cannondale. I created a crosshatch pattern on the rotor with some emery cloth. How you do this. First you clean and deglaze the rotor with some emery cloth. Then you go all the way around the braking surface with your emery cloth in one direction only. Then you go back over the braking surface with the emery cloth going in a 90° direction from the first pass. 

This morning, I cleaned the prepared rotor with some some soap and water and wiped it with alcohol. Clean. Then I pulled the pads again. Deglazed them slightly with some medium grit emery cloth and rinsed them with some alcohol. Swapped out the rotor and installed the replacement using the correct torque pattern. If you don't know, that's an "X" pattern in multiple steps such that the rotor is installed with uniform pressure all around. I don't have a torque wrench for the bike but I'm pretty sure I'm in the ball park. Reinstalled the wheel, checked the caliper position, tuned the rotor and adjusted the pads.

I don't know if this will work. I'll go out into the dry weather tomorrow and bed the brake in. We'll see if this does the trick.

Whatcha got?

I'd love to hear from all the disc brake folks about this sort of thing.  Is this really something some/many/all folks face with disc brakes face?  What you describe above is MORE maintenance than I have done on my bikes - in TOTAL - the past five years or more.  Change a chain, a cassette, lube the pedals, and replace a worn tire are about it for me.  I think I did replace the rim brake pads on my commuter a couple years ago, but man, this disc brake set-up seems a BEOTCH.  Maybe once it is done successfully it rarely needs to be done again? If it is more often than once every three years or so, then it is just annoying!  

Hoping @dennis or @ChrisL or @Dirtyhip has some longer term experience with taking care of disc brakes - set-up through expected maintenance effort.

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25 minutes ago, Razors Edge said:

I'd love to hear from all the disc brake folks about this sort of thing.  Is this really something some/many/all folks face with disc brakes face?  What you describe above is MORE maintenance than I have done on my bikes - in TOTAL - the past five years or more.  Change a chain, a cassette, lube the pedals, and replace a worn tire are about it for me.  I think I did replace the rim brake pads on my commuter a couple years ago, but man, this disc brake set-up seems a BEOTCH.  Maybe once it is done successfully it rarely needs to be done again? If it is more often than once every three years or so, then it is just annoying!  

Hoping @dennis or @ChrisL or @Dirtyhip has some longer term experience with taking care of disc brakes - set-up through expected maintenance effort.

My Fuji MTB had really loud brakes that new pads resolved.  The Sram Level TL’s on my Anthem are silent as are the TRP mechanical discs on my new crosser.

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54 minutes ago, Razors Edge said:

Maybe once it is done successfully it rarely needs to be done again?

Well, I am hoping so. Ultimately, if the squealing doesn't resolve, I expect I'll move to inexpensive pads. Cheap pads are likely to be quieter since they don't offer good grabbing ability.

I bed the new setup in yesterday. At this moment, the combination is quieter. I'm hoping as the brake gets used, it will calm down.

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I run XTR on the mountain bike. They can get loud when wet. Otherwise I have silent brakes. I run the ice tech stuff on my Cx. Those are also silent. Buy better brakes or get a better mechanic. We run the organic compound sometimes. They do wear very fast though.

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Aren't they BB7s? They are supposed to squeal. That's how people know you are coming. Seriously, I love BB7s, but they can howl. Try them on a fatbike in the snow. I figure this way the bears can hear me coming and run away.

I do very little maintenance on mine. Change the pads, clean the rotor with some alcohol, done. 

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Dumb question & slight thread jack but are disc brakes sold in pairs or individual brakes?   My TRP Spyres are OK but I was checking out the TRP HYRD (cable actuated hydro’s) and they were pretty reasonably priced assuming it’s a pair.  

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13 hours ago, ChrisL said:

Dumb question & slight thread jack but are disc brakes sold in pairs or individual brakes?   My TRP Spyres are OK but I was checking out the TRP HYRD (cable actuated hydro’s) and they were pretty reasonably priced assuming it’s a pair.  

The ones I have seen are sold individually. Assuming you are talking about the caliper, the part that hangs from the frame.

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I've been successful by taking the brakes out and doing several hard stops to seat everything and brake them in (pun intended).  No fooling around.  Get the bike up to speed and stop it as fast as you can without going over the top.

Beyond that I use a dial indicator and a rotor fork to get the rotors as true as possible.  I am assuming that you have rotors and calipers of the same brand here.  It's possible to mix Shimano rotors with other brand calipers (BB7's in my case) and have the brake track slightly intersect the open spaces between struts on the rotor as Shimano does not always use the same track (contact patch) diameter.  I have heard this was a situation with older designs but it's worth checking anyway.

Sometimes you can pull the pads out and put them back in and solve the noise problem.

Try the hard stops on cleaned brakes first as it seems to work the best.

Note:  my current setup is Avid BB7 mechanical calipers with resin pads and a Shimano centerloc rotor that is supposed to be used with metal pads.  I run extremely tight clearances between the pads and the rotor, only one or two adjuster clicks off of the sound of light scraping.  I can get away with that as I do not take the wheels off to mount on a rack and I am willing to spin the wheels and make a quick adjustment if I do have to remount a wheel.

 

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Everything is Avid. The back brake doesn't give me any problems. I wonder if, since the bike was in the show room for so long, the pads are somehow 'dried out' or something like that. It doesn't make any sense but there it is.

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31 minutes ago, donkpow said:

Everything is Avid. The back brake doesn't give me any problems. I wonder if, since the bike was in the show room for so long, the pads are somehow 'dried out' or something like that. It doesn't make any sense but there it is.

Is it possible that the caliper is mounted at a very slight angle.  It might be that loosening the caliper bolts and resetting the caliper in relation to the rotor may help.  This is a reach, but back in the day when I used rim brakes, pad angle would make a difference with regard to squeal.

I know that an important part of my setup is to get the rotor in the right place with the pads clamped down tight and the brake lever pulled firmly. (may take an extra hand).

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36 minutes ago, maddmaxx said:

Is it possible that the caliper is mounted at a very slight angle.  It might be that loosening the caliper bolts and resetting the caliper in relation to the rotor may help.  This is a reach, but back in the day when I used rim brakes, pad angle would make a difference with regard to squeal.

I know that an important part of my setup is to get the rotor in the right place with the pads clamped down tight and the brake lever pulled firmly. (may take an extra hand).

I've reset the caliper position several times. That's what led me to suspect the rotor as the problem, which has proven not to be the case. I did notice that the other rotor had a polished area in the track. You really shouldn't get a polished surface on a rotor.

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1 hour ago, donkpow said:

I've reset the caliper position several times. That's what led me to suspect the rotor as the problem, which has proven not to be the case. I did notice that the other rotor had a polished area in the track. You really shouldn't get a polished surface on a rotor.

I'm out of ideas then.  Try the hard braking then when you get a chance and see if by some magic it works.  It does for me as it is common for mine to squeal a bit if I haven't ridden in a while.

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2 hours ago, maddmaxx said:

I'm out of ideas then.  Try the hard braking then when you get a chance and see if by some magic it works.  It does for me as it is common for mine to squeal a bit if I haven't ridden in a while.

Oh yeah, I'll be looking at it. Right now I'm just letting it build up with long easy braking. The transfer of material should solve the problem, whichever method works.

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If none of this worked, used rotors make great trivets on a circle of cork.

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It still chatters. I just clean the disc and pads more often than should be needed. Since I don't need high speed braking on this machine that often, I usually just go a little easy on the front brakes and my nerves. I do need a nice little trivet. I am currently using an upside down pie pan.

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