Squealing rear brake

The Rookie

Herdwick wrote:

copper grease won't get on the braking surface of the pad unless you put it there, the same way it never gets when I apply it to a car or a bike brake pad to silence the annoying brake noise. please read the link

eg When a door creaks you spray some wd40 or whatever lubricant to the hinges to shut them up, the same applies for the damn pads!!! carefully applying some copper grease on the BACK of the pads will help eliminate the squealing, copper grease wont melt but rather stick to the surface applied, and won't contaminate other critical parts.

Oh dear, you don't get it yet.....

Car/ bike brakes get hot enough to burn off grease, you could get it there and not know, cycle brakes don't get hot enough, that has been said once, you may get away with it, you may not, it's not worth the risk when you could find yourself with no braking at a critical moment.

When you lube a hinge you lube the surfaces rubbing each other, the brake pad maybe move half an mm, but greasing that doesn't remove a squeal by aiding the pad moving as that is done in fraction of a second, not the seconds the squeal lasts it may work because the grease acts as an absorber, but it doesn't always because as you say it's a resonance and that may not be fixed by grease anyway (especially on Avid brakes).

Once you've understood that you'll see your suggestion is all wrong.

bykeshed

Strip the brake assembly, clean caliper and pads thoroughly with brake cleaner (I use brake cleaner from a motor factors), apply copper slip/grease onto piston and/or back of pads, re-assemble, adjust so that pads are ever-so-slightly in contact with the disc.

If they still squeal, buy new pads (current pads may be too contaminated), clean new pads with brake cleaner before assembling (don't touch pad surface after cleaning), apply copper slip/grease, re-assemble as above.

I experience an average of 1 in 50 bikes where the brakes still squeal after this and that's usually down to branding of the 'new' pads. Sometimes, like with cars and motorbikes, new products are already contaminated or faulty.

If you have one, there may be a slight chance that the anti-friction gasket is worn or missing. If there should be one, you may find copper slip/grease won't be enough to stop the resonance.

The Rookie

Why use the grease though, that is madness, do the rest, yes....

cooldad

Don't do this ^^^^^^^^^^^^^^ (Now two posts up - one finger typist)

Brake cleaner designed for cars will contaminate bike brakes which are much smaller and work at much lower temperatures.
Don't put any sort of grease or lube anywhere near the pads (or brakes for that matter). It will contaminate them.

If you must clean things (and it's a good idea to clean rotors before installing them), use isopropyl alcohol.

If pads are contaminated (most likely by doing some of the things in the previous post) replace them. And don't try 'cleaning' them first.

nicklouse

as above most Car brake cleaners contain a rust Inhibitor to stop the carst Iron discs rusting.

does not help your MTB Brakes one Little bit.