High pitched sound from rear brakes

[splat]

I edited my kerosene comment before you posted your comment, but i would not use it on brake surfaces. There seems to be a debate on whether it actually evaporates completely or leaves a residue; one that I'm not expert enough to confirm or deny.

As far as the 2nd to last comment that's why i put "/sarcasm" at the end....


In regards to the tire:
If in "very slight amount" you mean something that might get flung on the tire when cleaning or lubing the chain, the answer is is generally no. But any loss in traction is a big deal, so try not to---or at least minimize it. Alcohol will dry the rubber over time. Once won't kill ya, but I'd not do that either.

 

[ST Guy]

make sure the pads are also bled properly, both pucks even when out. Also, new pads need BREAK IN, if you were hard on them the first 50 miles or so then you could have glazed them over. My truck brakes just started squeeling even with new rotors and pads... I chocked it out to "character", if nothing is wrong then im ok with that.

The breakin period, if done correctly, can be accomplished in less than a half hour. (More if the rotors are not new.) It involves repeated stops to really heat up the pads and rotors and transfer the appropriate amount of pad material to the rotor.

Of course, doing this is more risky on a bike because you better know your braking limits or you go down. Easy to do on a car, though:

http://www.stoptech.com/technical-s...ions-and-procedures/stock-brake-system-bed-in

Some more good papers:

http://www.stoptech.com/technical-s...y-definitions-and-procedures/brake-pad-bed-in

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

 

[ST Guy]

Like they told you at Evolution, give the brakes a week or so to bed in. Even then, the sound may not go away. Brake squeal is pretty common, depending on pad compound. Cheap organic pads tend to be pretty quiet, but they don't usually work as well.

If the rotors are used, yes, it'll take longer to bed in. And if the rotors are new, it'll still take a while if you don't aggressively bed them in. (And most motorcyclists don't do this because of the risks involved.)

However, see the links I posted above.

It strikes me that it would be relatively easy to build a brake bedding machine. It would be similar to a dyno but would have a second front roller hooked up to the regular rear roller. You'd then strap the bike down on the machine, front and rear and then run it up to speed and do the repeated stops necessary to properly bed in the brakes. And since the bike was strapped in place, there'd be no risk of washing out the front end or doing an end-o.

 

[pannayar]

I cleaned the rotor with a little bit of isopropyl alcohol (I believe the can says rubbing alcohol, labeled 50% isopropyl). Is there any difference b/w ethyl & isopropyl in this regard? See this post.

On the evaporation question, for the WD40 wiki says clearly "The volatile hydrocarbon then evaporates, leaving the oil behind...". Yet to find some such info on kerosene. It most likely does the same (or at least takes a long time to evaporate) because of the lasting smell...

 

[ST Guy]

Rubbing alcohol is almost always 70% alcohol and 30% water. ('Never heard of 50%.). For most purposes, it's fine. We even use it in our clean room for wiping down sufaces and cleaning things. If the 70% doesn't do the job for you the 99.9% isn't really going to do any better in that case use actual brake cleaning fluid.

 

[pannayar]

Rubbing alcohol is almost always 70% alcohol and 30% water. ('Never heard of 50%.)

This is what I used.

...in that case use actual brake cleaning fluid.

Any specific ones?

Btw, is it fair to assume that the swing arm stand goof up (see OP) would have nothing to do with the squeal? The squeal started after that though.

 

[ST Guy]

Well, I wouldn't assume anything. Does the wheel still turn smoothly by hand? Is something rubbing on the rotor other than the pads? Etc.......

Weird.....I've never heard of 50% rubbing alcohol.

 

[CAmudgeon]

Evaporation requires heat. Heat requires friction. A contaminated brake system may never generate enough heat to evaporate the contamination. Just don't do it. Brake cleaner is the only liquid that should go on the brake linings.

my rear brake squeals like an old bus. It also stops me. A little anti squeal grease on the back of the pads may eliminate the squeal if it bothers you. Else just live with it or try an oem pad set.

 

[pannayar]

Yeah, stopping wise there is no issue. My 'bother' is because the squeal started after my fumble with the rear swing arm stand (a day after getting new pads, see OP), and was not there before that.

It is a little "consoling" to know that you have a old bus

As long as it is like a door hinge squealing w/o any functionality hindered, I am willing to get used to it

 

[terdog55]

Why not remove the pads for a visual inspection?

 

[ST Guy]

A contaminated brake system may never generate enough heat to evaporate the contamination. Just don't do it. Brake cleaner is the only liquid that should go on the brake linings.

Contamination usually just doesn't "evaporate". Usually it's some sort of chemical or organic material that either has to be removed with a solvent and washed away, or has to be burned off with a lot of heat (think red hot). And that usually leaves a residue anyway.

Best just to clean it with a product designed for the job.

And yea, they may be squealing 'just cause they do at some point. Some high temp brake grease on the back of the pad where the caliper contacts it may help. I recommend this: http://www.permatex.com/products-2/...le-use-ceramic-extreme-brake-lubricant-detail It's also available in small cans at most decent auto supply stores.