Squeaky disc brakes

tgotb

So the new crosser has disc brakes (Avid BB7), and they've started howling like banshees. I'm new to the whole disk brake thing; is there anything I can do to make them quieter?

At some point I assume I'll have to replace the pads. Is there an easy way to determine how worn they are without taking them out and examining them? On a commute where my caliper brakes needed new pads ~every 6 weeks in the Winter, how long can I expect the pads in my disk brakes to last?

Obviously if I don't solve the noise issue they'll last for ever, because I'll be too embarassed to use them...

EKE_38BPM

WD40 or GT45 on the discs!

PLEASE DON'T DO THIS. It is a joke.

gtvlusso

apply some coppaslip (copper grease) to the backs of the pads (the bits that touch the piston, not the disk!

Aidy

TGOTB wrote:

So the new crosser has disc brakes (Avid BB7), and they've started howling like banshees. I'm new to the whole disk brake thing; is there anything I can do to make them quieter?

At some point I assume I'll have to replace the pads. Is there an easy way to determine how worn they are without taking them out and examining them? On a commute where my caliper brakes needed new pads ~every 6 weeks in the Winter, how long can I expect the pads in my disk brakes to last?

Obviously if I don't solve the noise issue they'll last for ever, because I'll be too embarassed to use them...

Make sure there's no crap on the disc/pads. Make sure the callipers are set up properly (pads should be parallel to the disc, and the disc shouldn't flex under braking).

Simplest way of checking pads is to pop the wheel out and have a peer. Assuming you're running sintered pads (and it would be silly to be running anything else), and on road only, I reckon you'd see out the entire winter and some on a set of pads.

bails87

I've got BB5s and can see the pad thickness without removing the wheels. Just look down through the caliper.

When you do need pads, Superstar are excellent value, and decent pads too. Sintered should be fine for road use.

veronese68

gtvlusso wrote:

apply some coppaslip (copper grease) to the backs of the pads (the bits that touch the piston, not the disk!

+1 to this.
Also, do the pads have a groove cut down the middle of the material? That helps reduce squeal, if they don't have a groove but have plenty of material left cut a groove in them.
The squealing is caused by vibration. Check everything is tight.
Are the pads glazed? Clean them up on a bit of emery over a flat surface.
These are fixes that work on cars and motorbikes, same principles apply.

tgotb

Veronese68 wrote:

gtvlusso wrote:

apply some coppaslip (copper grease) to the backs of the pads (the bits that touch the piston, not the disk!

+1 to this.
Also, do the pads have a groove cut down the middle of the material? That helps reduce squeal, if they don't have a groove but have plenty of material left cut a groove in them.
The squealing is caused by vibration. Check everything is tight.
Are the pads glazed? Clean them up on a bit of emery over a flat surface.
These are fixes that work on cars and motorbikes, same principles apply.

Thanks, all makes sense. Groove parallel or perpendicular to direction of movement of disc?

rolf_f

bails87 wrote:

Superstar are excellent value, and decent pads too. Sintered should be fine for road use.

I'm not sure if I blame my Superstar pads or my crap Avid Juicy 3 calipers but I kept losing pads - the pad material kept dropping off the backs leaving a nice corroded surface. I'm disinclined to try again!

Aidy

Rolf F wrote:

I'm not sure if I blame my Superstar pads or my crap Avid Juicy 3 calipers but I kept losing pads - the pad material kept dropping off the backs leaving a nice corroded surface. I'm disinclined to try again!

I think that's a reasonably common complaint, although I've had no issues with them (and I've used a *lot* of superstar pads).

Do you bed them in properly?

Stevo_666

Sometimes all it takes for me to shut my squeaking pdds up is to give a few short sharpish pulls on the brake lever when going at speed/downhill.

nicklouse

http://www.sram.com/sites/default/files ... 08-000.pdf

Coppa paste is not needed. Never needed it on any cycle. But have used it often with cars etc.

Also mke sure the disc is correctly offset due to the caliper only moving one pad.

veronese68

Groove radial to the wheel. ie across the pad so the disc wipes across the groove not along it.

Ouija

Got BB5's, got BB7's. The squeal is caused by dirt and grease on the rotors (can also be on the pads, which is why you should never touch pads with your fingers.. as the oils in your skin can ruin them). Simply wiping them with a cloth, whilst it might get rid of visible dirt, won't necessarily degrease them. Need to buy a rotor degreaser from your LBS or Halfords bike section. Be careful not to get any in the calipers. Apply once a week. Makes the squeal go away and gives your pads more bite (squeal being the first sign that your braking performance is being compromised).

bails87

Rolf F wrote:

bails87 wrote:

Superstar are excellent value, and decent pads too. Sintered should be fine for road use.

I'm not sure if I blame my Superstar pads or my crap Avid Juicy 3 calipers but I kept losing pads - the pad material kept dropping off the backs leaving a nice corroded surface. I'm disinclined to try again!

That was a problem a long time ago, they seem to have rectified it now.

essex-commuter

All I do is wipe the rotors over once a week or so with a clean cloth and white spirit. Takes 30 seconds, the brakes are back at full power within 2 or 3 pulls and no squeals. Unless it rains heavy, then I can't stop the squeals...but at least I can still stop!

Why are sintered so much better than organic? I thought organic wore quicker but were less prone to squeal than sintered, is this not true?

OP: 6 weeks to wear out a pair of caliper brake pads - really?!

bails87

essex-commuter wrote:

Why are sintered so much better than organic? I thought organic wore quicker but were less prone to squeal than sintered, is this not true?

Sintered don't deal with heat as well as organic, they also don't grab quite as well, but they last longer.

The first two issues are more of a problem for downhill racers than commuters though. As for noise....I really don't know. It seems to depend on the brake and rotor as much as the pad.

tgotb

essex-commuter wrote:

OP: 6 weeks to wear out a pair of caliper brake pads - really?!

Yeah, though it is a bit of a worst-case scenario. Bike tends to pick up a lot of sandy grit in Richmond Park (gets carried onto the road by horses), and this combines with the general Winter muck to create a rather effective grinding paste; added to this, when it's freezing outside I'm not as diligent as I could be about cleaning the bike. Six weeks is probably a thousand miles, and that's enough to destroy a pair of pads. I also get through chains at a horrendous rate.
In the Summer, a pair of the same pads lasts well over 6 months...