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Vibration from rear disk brake


Windbreaker

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So I got a brand new Merida 120 for Xmas from Santa (well via the darling wife anyway Wink) and on the second ride the rear brakes started to make a helluva noise.

 

Took it back to the lbs. They took the shine off the pads, re-inserted and away I went - perfect. Well for one ride anyway then it was back to the same complaining noise every time I use them . The only time they don't squeal is when I really brake hard on tar.

 

So they replaced the pads telling me that sometimes they get a "dud" or two.

 

Yep, you guessed it, one ride later and back to square one. Now what? I've been told that I need to get this that or the other type of brake pads but I am not sure.

 

Anyone?

 

Windbreaker2010-01-26 14:24:35

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Maybe it's 'contamination' on the rotor? I would suggest giving it a good clean with some of those alcohol swabs you get for cleaning glasses, worked for me .....

 

Just a thought!
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I had the exact problem, I was using Shimano XT's I eventually got new pads but that didnt help, so It must have been the disc, because I now have new brakes and The problem is gone.

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Must say I had the xt's and hated them, servo wave is such BS !

Had endless rubbing and not much power. 

 

My new R1's though are out of this world.
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If cleaning the rotor doesn't solve your problem, take the bike back to the LBS and ask them to check that the pistons inside the rear caliper aren't stuck

 
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Vibration/ squealing is caused by someting being loose, start by checking the caliper is tight, the wheel in the frame is tight, the rotor, spokes, etc any one of thesse can cause the brakes to make a noise, contamination has been covered already...

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My XT's are just perfect!!

Second set of pads already.....not probs yet.

 

As for stopping power? Plenty enough to bring my 90kg's to a halt very quicklyApprove....downhill and on the road.

 

It is also how you use your brakes - feather them don't abuse them!!

I clean the rotors with some acetone every now and again and make a poit not to touch them at all with bare hands.

 

Works well for me...

 

 
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Vibration/ squealing is caused by someting being loose' date=' start by checking the caliper is tight, the wheel in the frame is tight, the rotor, spokes, etc any one of thesse can cause the brakes to make a noise, contamination has been covered already...[/quote']

 

It could be, but its not always, its the vibration from the brakes shuddering which reaches the frames natural vibration frequency.. Cant remember the story but you remember the story about the bridge in the states, the wind made it start vibrating swinging and later it was like waves comming down the bridge till it broke, Another example is  when you run your finger on the rim of a wineglass and it starts vibrating and making the sound.... you know the one?

 

Well thats what happened. I had it and everything on my bike was tightened to the max.
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Agreed Bos I've had two identical bikes, same wheels, brakes same size frame etc and one bike's brakes make a noise and the other doesn't, But I have found that a lot of people over look these other causes.

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Ok, cleaned the rotor with acetone - no alcohol available. I don't think that acetone leaves a residue.

 

Took the shine off the pads with sandpaper, re-inserted the pads.

 

Checked everything for any loose bits.

 

I live on a hill. Got some speed up and applied the brakes hard - 5s on 10s off etc

 

First 50m meters no noise but also not much stopping power. After 50m the vibration/squeal started and I had proper braking.

 

Something I never mentioned before. I also changed out the wheel. The problem is on both the original wheel and the replacement so it can't be the rotor. (Both could have been contaminated).

 

I don't hear any noise that I would link to a rubbing pad so I am quite sure that the pistons are releasing.

 

 

 

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mmmm Silver Ones, with black stuff on them LOL

 

edit: to note that this comment was as a result of a computer hijack. can't trust a woman alone with a laptop LOL

 

 

Windbreaker2010-01-27 13:00:00

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I had a very similar challange with my Shim M485 hyd discs..eventually they were replaced under warrenty and that solved the problem. Hope that you dont have to go to this extent.

 

Otherwise..how is your 120 going ? I have one in my sights for later this year..
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