sanding disc brake rotors

[fmradio516]

So a couple years ago I bought a set of BB7s. At the same time, I bought a set of rotors and pads. Did _some_ research on how to break them in. Somehow I did it wrong(i forgot what method I used) and they felt like crap and made a ton of noise. I tried cleaning the rotors and running some sand paper on the pads, but it never fixed it.

Fast forward a couple months and I pull the trigger on a new set of pads and rotors to take a whack at it again. I went with the speed up, slow down, speed up, slow down, speed up, slow down method. But I think I over did it. Took it to a massive hill in my area and did it multiple times all the way down. Well I think they got too hot as right after, there was a bronze tint to parts of the rotors. I have been riding them ever since, but they do also feel like crap and make a ton of noise.

But now the frame they were on broke and im getting ready to built up a new one with the same parts. While I have everything off, I was going to pull the rotors off, give them a clean with some alcohol, then touch them to the belt sander for a second, clean again.

Can anyone advise against this? Any grit recommended? Was thinking 600. They are smooth, so im not trying to resurface them, just trying to get some virgin metal to show. Id prob run the pads on some sand paper as well in case they are glazed.

Am I totally crazy?

[charliedid]

So a couple years ago I bought a set of BB7s. At the same time, I bought a set of rotors and pads. Did _some_ research on how to break them in. Somehow I did it wrong(i forgot what method I used) and they felt like crap and made a ton of noise. I tried cleaning the rotors and running some sand paper on the pads, but it never fixed it.

Fast forward a couple months and I pull the trigger on a new set of pads and rotors to take a whack at it again. I went with the speed up, slow down, speed up, slow down, speed up, slow down method. But I think I over did it. Took it to a massive hill in my area and did it multiple times all the way down. Well I think they got too hot as right after, there was a bronze tint to parts of the rotors. I have been riding them ever since, but they do also feel like crap and make a ton of noise.

But now the frame they were on broke and im getting ready to built up a new one with the same parts. While I have everything off, I was going to pull the rotors off, give them a clean with some alcohol, then touch them to the belt sander for a second, clean again.

Can anyone advise against this? Any grit recommended? Was thinking 600. They are smooth, so im not trying to resurface them, just trying to get some virgin metal to show. Id prob run the pads on some sand paper as well in case they are glazed.

Am I totally crazy?

I think you will destroy them. (Rotors)

Try some of this stuff below...and then bed them in riding slow and ride the brake but don't come to a complete stop before letting off the brake repeating 5-6 times at a mild then slow speed. This is what you were doing but overdid it on the hill maybe? Deglazing the pads is not a bad idea though. Just don't over do it.

This *might* work :-)


https://www.amazon.com/Squeal-Anti-Squeal-Disc-Brake-Paste/dp/B004JKD00O/ref=sr_1_1?hvadid=241918359586&hvdev=c&hvlocphy=9021731&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=10467689241749328534&hvtargid=kwd-31786175301&keywords=squeal+out&qid=1549815933&s=gateway&sr=8-1&tag=googhydr-20

[fmradio516]

I think you will destroy them. (Rotors)

Try some of this stuff below...and then bed them in riding slow and ride the brake but don't come to a complete stop before letting off the brake repeating 5-6 times at a mild then slow speed. This is what you were doing but overdid it on the hill maybe? Deglazing the pads is not a bad idea though. Just don't over do it.

This *might* work :-)


https://www.amazon.com/Squeal-Anti-Squeal-Disc-Brake-Paste/dp/B004JKD00O/ref=sr_1_1?hvadid=241918359586&hvdev=c&hvlocphy=9021731&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=10467689241749328534&hvtargid=kwd-31786175301&keywords=squeal+out&qid=1549815933&s=gateway&sr=8-1&tag=googhydr-20

Thanks but I should have specified that its more of a grinding noise. Less of a squeal. Not sure if that stuff still applies.

I will try just hitting the pads lightly. I was only going to touch each portion of the rotor briefly just to get a neutral surface again; though it might be harder than I thought to do it evenly. It would probably matter less if I did say 1000grit.

[Vientomas]

https://www.pinkbike.com/news/Tech-Tuesday-Silence-That-Squeaky-Disc-Brake-2011.html

I've sanded rotors and they worked perfectly thereafter. Click pics for more instruction.

[dddd]

The rotors will need some fresh breaking-in after any refinishing efforts, but best break in is done by gradually increasing the braking energy (heat input) over the course of perhaps hours of use (depending of course on how much descending you are doing.

Getting the rotors hot is not breaking them in, they should be broken in first before any high-heat braking. Normal trail riding is perfect for this, descending into the canyon is not.

I suspect your pad type is part of the problem, you didn't say what type (organic/metallic) and brand of pads you are using.

Changing to a different rotor with either different cutout shapes or different metal (alloying and/or processing) can also make a big difference in what type and level of noise occurs.

BB7's and other legacy Avid disc brakes are inherently noisy, a solid honk from the front rotor during heavy braking is expected with organic pads.
Shimano disc brakes (mechanical and hydraulic) are inexpensive these days and are much quieter than BB7's any day.

[Steve in SLO]

Would give Scotchbrite/alcohol a whirl.

[stien]

Came here to say to use alcohol. On the rotors!

[fmradio516]

I have already gave them a touch on the belt sander and then cleaned them with brake cleaner. Ill use some alcohol too before I put them back together.

As for the pads, ill do as they do in the link and take a couple passes on a piece of sand paper on a flat surface.

[SkyRider]

I have a few thoughts for you. First I would ask if the frame was faced prior to the original installation. Poorly faced brake mounts can add to noise especially in a single action brake such as bb7. What rotors and pads are you using? With certain compounds I would expect the bronze color you described. I would also add that some rotors are more prone to making noise than others and if you have an older avid design there is almost no way to get them quiet. From a shop and racing perspective I would not try to sand pads and rotors. If you truly believe that they are burned then the metal has changed and they are no longer safe. If you feel that your noise is from contaminated pads and rotors and the contamination is deep enough that sanding is your answer then again what you have is a safety issue since you will need to remove significant amounts of material and may also over heat the materials again. Cleaning/resurfacing brakes works on cars because of the thickness of the materials involved, bicycle brakes are to thin for that sort of treatment in my experience. Pads and rotors are cheap, dental work isn’t.

[fogrider]

I have already gave them a touch on the belt sander and then cleaned them with brake cleaner. Ill use some alcohol too before I put them back together.

As for the pads, ill do as they do in the link and take a couple passes on a piece of sand paper on a flat surface.

Alcohol is fine, but finish with soap and water! Same with the pads. When I cleaned with alcohol, it sill made a lot of noise, soap and water does wonders! I like dish washing liquid, it gets nice and bubbly...soak the pads for a couple of minutes.

[fmradio516]

thanks for the inputs everyone!

[charliedid]

https://www.pinkbike.com/news/Tech-Tuesday-Silence-That-Squeaky-Disc-Brake-2011.html

I've sanded rotors and they worked perfectly thereafter. Click pics for more instruction.

Belt sander? :-)

[charliedid]

thanks for the inputs everyone!

Let us know how it goes. I've always found disc brakes to be a bit of a struggle in the environments I ride it.

[Mikej]

Let us know how it goes. I've always found disc brakes to be a bit of a struggle in the environments I ride it.

Get some rotors-geez

[fmradio516]

Well I did the deed today. Also took apart the BB7s and cleaned them up a bit. There was a ton of hard corrosion on the plates. Its still there, but not as bad. I should have my build done by the end of the week, so we'll see how they work!

[Vientomas]

Belt sander? :-)

Ah, no...as per the suggestions in the link. Hand sanding.

[charliedid]

Ah, no...as per the suggestions in the link. Hand sanding.

Nevermind

That was my point.

Carry on