Mountain Biking - serious braking problems

i have basic shimano cable disc brakes, nothing special, anyway i am problems with my rear brake. when i brake, just before the wheel locks up at max braking point, this massive great squeal/vibration goes all up the frame, i have tried to adjust the inside pad(the one that doesn't move) but the screw got jammed, to the point where i had a pipe over the allen key and it twisted all in where the key & bolt lock together. this is incredibly annoying and effects braking performance somewhat. now, does anybody know whats going on and/or can they tell me how to fix the problem, i don't really want to pay through the nose for a bloke at the lbs just to have a look at it, thanks guys:D

Umm that's kinda odd. Mine does something similar where it vibs a tad bit right before lock up....so squealing...hmm...I dunno :\

Your squeal could be 1 or 2 things.
1. Off center contact. In discs since the pads are not fastened solidly (usually) a light force can make them vibrate. It doesnt usually happen but if the pads are off center enough the one that is farther apart will be prone to it.
2. Lubricated pads. It could be anything from grass sap up to bearin greas or chain oil. The easiest way to tell is to look at the rotor. Is there any discoloration other than silver on the rotors? If there is any kind of blue/yellow/green, they have oil on them and the pads. I have a post elsewhere on the site on how to deal with that event.

The shimano cable discs give you a bad first impression of how good discs are. You shouldnt have had to use a pipe/allen wrench to adjust the fixed pad. I think you might have been able to take the wheel off, releasing pressure on that pad, and then adjusting it. When you turn the adjuster a click, it pushes the pad forward, and then backward a little bit and winds up little closer than before you adjust it.

ok, i have figured out what the problem is, on the inside pad, the one that doesn't move, the pad rests flush up against a metal plate which is held in place by a bolt, now that bolt is sticking about 1 mm out from this plate, so the pad rest up against this and is a bit loose, somehow i hav minorly fixed this problem, but the brake does not feel right, not there is a surclip and a spring washer on the outside of the bolt, now my dad said about using a thing called quick-out, which is sorta like a reverse thread into the burred hole in the bolt, but i am concerned i could really screw something up, the other suggestion was to drill it out, but i thought that was a bad idea, and the fell of the disc's was so good when i first got them, after not even having v's before, i went over the handlebars quite a bit, but i hav also thought about buying a whole new bit, and salvaging the pads and internals for spares, problem is i don't know how much a new brake is, discluding the disc, as the disc itself is dead straight, but thatnks for the help people

Take off the shimano caliper, throw it in the trash, and put an Avid caliper in it's place. That's what I did, much better now :)

well, how about i swap the front and back and chuck some hydros on the front? how much is one lx deore hydro?

You are being a bit hard on the Shimano mechanical discs- I have them on my commuter and they work quite well- I have had ZERO problems with them - it is a good idea of course to adjust them (correctly) every so often and Shimano do provide service instructions on their web site to this effect. If you follow them you should not
have any problems.

CASH IS AN ISSUE, as i am saving up for, PSYLO"S, YAY!

If the screw must come out then yes, I would agree with dad on the EZ-out. They are far easier than trying to drill out an allen screw. More often than not, allen screws are hardened so it makes drilling a real pain. Another trick I have learned is to have both metric allen wrenches and SAE. There have been quite a few times the SAE size has worked with an almosr ruined allen bolt enough to get it out.

do what notfred and i did: get some avids and throw the shimanos in the trash.

same as notfred and dirtbike, get rid of the stock shimanos and get 6" or 8" aivd BB 7's they are 60 to 90 bucks and work worth every cent. the rotors of the avids are so much sexier too.

same as notfred and dirtbike, get rid of the stock shimanos and get 6" or 8" aivd BB 7's they are 60 to 90 bucks and work worth every cent. the rotors of the avids are so much sexier too.The stock Avid rotors aren't as sexy as mine. :D

http://img70.imageshack.us/img70/5154/RaiynRockhopper6.jpg

But yes, the Shi*No mechanicals SUCK in comparision to the Avid Mechanicals

are those the hope gothics?

are those the hope gothics?
Yeppers. Best rotor I've used with my Avids

hmmm 2 post in one day with people having problems with shimano mechs... i wonder what this means

mabey you should buy an avid, it will fix all of shimanos problems

Whats SAE, inpa?

In the world of wrenches there is Metric and Soceity of Automotive Engineers(SAE). Most cycling stuff and really most non-usa machinery is metric. American cars, aircraft, some old bikes are SAE. Those are the ones sized by fractions of an inch(5/16, 1/2 etc.)

What I am referring to is the Metric sized wrench may not fit, due to a ruined fastener, but sometimes the next size in SAE(which would be usually a half-step or so bigger) might fit well enough to save it.

Don't forget british standard, in use on a lot of bikes.

isnt british standard metric?