Howling brakes

[Bigtallfatbloke]

I have just re set up my brakes, they were fine before but now they howl badly...horrible noises, very scary and frightened the neighbours cats...any way...I tried the sand paper trick...no joy. The pads are getting close to the wear lines now...I can t see any metal...and they are not wet. I think I set thenm up correctly...they certainly look fine to me.

Is this typical of worn pads ...shall I just replace them? I reckon there are a few hubndred miles in thiese yet though...skinflint I hear you cry

 

[domtyler]

Just wear ear plugs.

 

[LLB]

I had this happen and it was caused by a very small piece of grit on the brake block.

Take a close look (feel) for this before going further with it.

Just realised, it may be pad and disk arrangement

Check for warpage on the disk, and wear on the caliper slider pins as this can cause this problem

 

[ChrisKH]

Have you dropped any oil on the rim? I had this problem a while back. Worn pads shouldn't be more noisy. Would replace pads and clean rim if oil is a possibility.

 

[Amanda P]

If the blocks are nearly worn out, perhaps replace them first. You may not realise that they are worn out until the metal inside starts gouging into the rim. Blocks can wear quite fast on a wet mountain pass descent (as I found out coming down the Conor Pass on a filthy wet afternoon with worn blocks and a brand-new rim).

That may solve the problem - and you'll have to set the brakes up again then anyway.

 

[Amanda P]

You know about toe-ing in, right?

 

[Bigtallfatbloke]

I will replace the pads I think. It is possible there is some oil on th erims...although I was very careful and cleaned th erims after wards. I have set the brake pads so that they are parralel with the rims as they turn. I heard that perhaps angling the rear of the pad up a touch is a cool thing to do (is that toeing in??)...I didnt do that because th epads are worn almost to the line and I thought if I kept them level they might last longer...hmm...maybe I will try changing their angle before I re fit new pads...thanks.

 

[Amanda P]

Opinion seems divided on whether you should set the pads so that the front edge touches the rim just before the back edge, or vice versa.

Either way, if the pads hit the rim absolutely dead square on, that can cause squealing.

Other possible cures:

• lightly file the faces of the pads to remove a glazed layer that sometimes builds up.
• clean the rims thoroughly to remove any grease or black gunge
• check for play anywhere in the brake arms - if they're flexing anywhere, try to stop them (without stopping the brakes working, obviously)

Some brakes are more prone to squealing than others; I suspect it has to do with how stiff the arms are. Wobbly, flexible arms are more prone to squeal than stiff ones.

 

[Smokin Joe]

Opinion seems divided on whether you should set the pads so that the front edge touches the rim just before the back edge, or vice versa.

Either way, if the pads hit the rim absolutely dead square on, that can cause squealing.

Other possible cures:

• lightly file the faces of the pads to remove a glazed layer that sometimes builds up.
• clean the rims thoroughly to remove any grease or black gunge
• check for play anywhere in the brake arms - if they're flexing anywhere, try to stop them (without stopping the brakes working, obviously)

Some brakes are more prone to squealing than others; I suspect it has to do with how stiff the arms are. Wobbly, flexible arms are more prone to squeal than stiff ones.

Nope.

Toe the blocks in as much as you like and after a couple of rides they will be hitting the rim dead square. Think about it.

 

[Amanda P]

Well, no. My experience is that they don't.

As you squeeze the lever, one end of the (toed-in) brake block touches the rim first. Squeeze harder, and the brake arm twists so that more of the block face meets the rim. As you let go, the arm un-twists again.

Maybe if you have super-stiff, short-armed brakes this wouldn't happen, but on most cantis it does. (Cantilever brakes on your Galaxy, BTFB?)

Actually, since writing this, I had a quick look at Chris Juden's wisdom, which is worth reading...

 

[mondobongo]

Replace the pads, its false economy trying to eke them out a little more if you miss them wearing out you will knacker the rim. Metal on metal will squeal then.

Give your rims a really good clean and fit new pads should cure the problem.