[wood booger]

I am sure it has been mentioned here before, but I couldn't find anything.

When grabbing some rear brake at speed the whole rear end of the bike (a little over 6" of travel) vibrates to the point that it is scary. Almost a harmonic vibration/howl.

I have been running the brakes for 6+ months w/ no problem. Started in the last month or so. Ran the brakes hard all winter in the slop.

I know Avid has had rotor issues in the past, but this just started happening. Gen 3 (?) 160mm rotor and mag caliper.

Has the soft mag caliper worn in the piston bore?

Thoughts? Ideas on how to fix? I am switching to a 185 anyway, but I am open to suggestions.

 

[offtheedge]

hayes V8 rotors

 

[RUFUS]

Stupid question but have you changed out the pads?

 

[davetrump]

doubt you wore the bore in the caliper, not only is that super hard to do, it would result in a rapid loss of brake fluid.

like rufus said, replace pads

scrub rotor w/ alcohol and check that rotor is not warped too bad/ scratched excessively, etc.

noise is caused by vibration, and vibration is usually caused by misalignment or contaminated pads (pads are bad if the brakes howl but fail to stop)

hope this helps... and the thread does not get derailed by the guys in the boxxer hate thread

I am sure it has been mentioned here before, but I couldn't find anything.

When grabbing some rear brake at speed the whole rear end of the bike (a little over 6" of travel) vibrates to the point that it is scary. Almost a harmonic vibration/howl.

I have been running the brakes for 6+ months w/ no problem. Started in the last month or so. Ran the brakes hard all winter in the slop.

I know Avid has had rotor issues in the past, but this just started happening. Gen 3 (?) 160mm rotor and mag caliper.

Has the soft mag caliper worn in the piston bore?

Thoughts? Ideas on how to fix? I am switching to a 185 anyway, but I am open to suggestions.

 

[DhDork]

Make sure ALL bolts are tight. When you grab your brake, and something has play, this can cause previously mentioned "vibrations". Check the mounting bolts, the adapter bolts and rotor bolts. Pads on the 'non-paddy' side could also be worn out and causing them to move around a bit. Then your pads and rotor could be contaminated. Burn them, alcohol, sand them, file them, whatever. Get a fresh new layer of pad and rotor to grab on to. Also make sure your caliper is properly aligned. When the pads are hitting at an angle, this can cause a loud howl as well.

 

[Jm_]

I've had this problem with Avid Codes. It seems to be most prevalent with avid hydro brakes, and some have hinted that maybe avid doesn't do enough pad-material research.

In any case, anyone who knows a "sure fire" way of solving this really doesn't understand what is happening. It's a combination of the caliper, the pads, the frame, the rotor, and all those parts interacting and allowing a resonant frequency to propagate. If one of those parts was different enough it might stop the propagation, but you can't really know which one it is, or even if it will fix the problem. All you can really do is try a lot of these different things, different rotors, pads, etc.

The vibration is extreme, and I'd lose control of my bike back when it was real bad. I flipped the front rotor to the other direction and it works great like that. The rear brake eventually bedded in and it went away, but it took a LONG time, and maybe the front was somehow contributing to both brakes vibrating. When you talk about this problem, some people think it's "squeal" or whatever, but this ain't even close.

 

[wood booger]

Defintely not a pad contamination issue. I know what that is like, this is much different. Like JM says the the whole rear end vibrates so bad that it can be scary at times. Never experienced this before and I have been on discs for at least 10 years.

The pads are new, but I did switch from organic to sintered a few pads back.

Never had the problem w/ organic pads, and didn't have it with the sintered pads for a while.

I have centered and aligned everything and all bolts are tight.

Anyone consider the spindly cast adapter that Avid uses these days?

Anyway, today I will put on a fresh 185 rotor, new pads (sintered again), and an older stlye "solid machined from a block" adapter. I hope it works.

 

[Jm_]

Let us know if it helps. I also took out the avid CPS stuff and replaced it with solid stuff, it helped a little for a few days, but then the vibrations came back.

 

[KillerSloth]

I have the same issue with my Elixirs on the rear of my Coiler... It has been like that since I got them though (the first ride may have been fine). I have tried realigning the caliper a couple times and that hasn't worked. I am thinking about going to a 10mm bolt on axle instead of QR, hoping that it will help (flex issues maybe?). I'll try the cleaning of the rotor/pads and see if that works too.

It is a LOUD howl and pretty bad vibration (also doesn't seem to stop that well), just like you are describing. I don't think it would be contamination either since it has been like that since the beginning, but you never know.

It actually seems to go away if I drag the rear brake for a while, and don't fully let off. So I don't know what would cause that.

The front is fine, other than the adapter wasn't long enough, so I have to add some spacers to it.

 

[SylentK]

I had the same issue with mine, howling from the rear, but it went away after a while (a month?). I think it has something to do with being "broken in" or something like that...

 

[wood booger]

I have the same issue with my Elixirs on the rear of my Coiler... It has been like that since I got them though (the first ride may have been fine). I have tried realigning the caliper a couple times and that hasn't worked. I am thinking about going to a 10mm bolt on axle instead of QR, hoping that it will help (flex issues maybe?). I'll try the cleaning of the rotor/pads and see if that works too.

It is a LOUD howl and pretty bad vibration (also doesn't seem to stop that well), just like you are describing. I don't think it would be contamination either since it has been like that since the beginning, but you never know.

It actually seems to go away if I drag the rear brake for a while, and don't fully let off. So I don't know what would cause that.
The front is fine, other than the adapter wasn't long enough, so I have to add some spacers to it.

Mine does the same. If I grab a bunch of brake real fast then let off a bit it vibrates and then is okay. (a great habit to develope, "grab a bunch of rear brake real hard right before you want to actually brake) Almost like a glazed pad thing.

Are you other guys w/ the issue running the sintered pads?


Bike will be switched tonight but not ridden until Thur night. We will see......

 

[KillerSloth]

I'm still running the stock pads.

 

[wood booger]

So so for the first step I just switched rotors (same size) and put some new pads (still sintered) in.

Just barely got them broken in last night, but no vibration/howl!

I took the Gen3 rotor off and put an older one on. We will see if it makes it through the weekend in silence.

 

[tahoefreerider]

So did the new pads and rotor fix it? I'm having the same problem on my new Remedy. It didn't have a problem on the first ride, but since then its been constant.

 

[KillerSloth]

My friend was riding my bike and it still had that vibration/howl so while we were going down a steep road on the way to a trail he drug the brake... It pretty much got rid of it! I'm thinking it may be the rotor, I think because of all the holes it has sharp edges/burs that catch on the pad, so maybe draggin the brake cleaned it up a bit... Could also try buffing down the edges of all the little holes...

 

[wood booger]

So did the new pads and rotor fix it? I'm having the same problem on my new Remedy. It didn't have a problem on the first ride, but since then its been constant.

Nope, it went away for a bit, but is now back.

I am putting on a bigger rotor (185) and will see how that goes.

After talking to some people w/ similar issues, it seems like a small air bubble in the caliper could be the culprit also. The theory is that if there is a bubble behind one of the pistons it can cause it to have inconsistent pressure on that side and can lead to a vibration/howl occuring. One pad bites, the other "mushes".

Bigger rotor, bleed the brakes, hopefully that does it.

 

[adam12]

check the hub and make sure it has not come loose. Mine started howling this wknd and after going thru the brakes completely...i just grabbed the wheel...it had a little play in it. I tightened it up and away went the sound