Disk Brakes not releasing

[Elvis]

My XTR disk brakes are not releasing properly. It looks like dust contaminated the movement of the two pistons. Any advice on how to clean this?

[Elvis]

BUMP

[Daxiet]

I'm sure this suggestion will be shocking to some.

 

With my Juicy's I had the same issue, well the one piston was more bad behaved than the other. I opted to pump the brakes so that the calipers came out as far as possible while still allowing me room to get a tool in to press the pistons back in again. When the pistons where fully extended I tried spraying them all over with brake cleaner. In all honesty I didn't find this too effective so I resorted to the "evil" substance known as Q20. After fully extending spraying with Q20 and compressing the pistons a number of times the calipers behaved well.

 

The catch however is that lubrication close to a braking surface is risky and if it gets in contact with your pads will contaminate them (that can be worked around), I cleaned the excess Q20 with brake cleaner trying not to let it attack the Q20 that had got in around the pistons.

 

Disclaimer: Use at own risk

 

[DownhillGuru]

Good advice from  Daxiet.

[Bike Mob]

clean with brake cleaner while extended, lube with brake fluid.

 

return, and you will probably need to rebleed.

 

[Plentipotential]

clean with brake cleaner while extended' date=' lube with brake fluid.

return, and you will probably need to rebleed.
[/quote']

 

If your system uses mineral oil instead of brake fluid then lube with the mineral oil otherwise the brake fluid is gonna eat something in there. I have the xt system and it uses mineral oil, ask me how I know

[Cassie]

So, does anyone know what is in these so called break cleaners?

Will any type of degreaser (i.e acetone?) perhaps also work?

 

What is the exact purpose of the break cleaner sprays? Only degreasing?

 

 

[Johan Bornman]

Cassie, I have no idea. But since brake fluid is water soluble, I suspect soapy water. They won't be made for oil-based brakes since it is an automotive product where they only use brake fluid.

 

I think Daxiet's Q20 spray is a good idea. If it works, it works. A bit of Q20 contamination in oil inside wont do any harm either. At the end of the day you want to remove whatgever it is that's jamming the piston and Q-20 removes gunk quite effectively thanks to the solvent in there.

 

 

 

[GTfan]

So' date=' does anyone know what is in these so called break cleaners?

Will any type of degreaser (i.e acetone?) perhaps also work?

 

What is the exact purpose of the break cleaner sprays? Only degreasing?

 

 

[/quote']

 

I've always sworn by Clean Green, well to clean the chain and coggs etc, dunno how well it cleans breaks but it's worth a shot.. but don't take my advice, rather go to your lbs and ask them what they would do