Push bike - Disk brake problem!!!

Jenks · World Chat Champion Joined: 22 May 2006 Karma :

Just as a few things to rule out, before i go and strip it or buy new parts....

Its a Trek 6000 Disk...

Both brakes were brilliant, Could lock up both wheels with ease, Stand it on the front wheel very very easily.

Now, we brought it back with us, from england to germany on a carrier...

Through rain and everything...

I Then tested her about 2 weeks later, and the front brake has gone rubbish..

Both brakes were squeeking like mad, But the rear has eased off abit, Only squeeks now and again.. But the front has stayed, it squeeks alot when you squeeze hard on the lever...
And wont lock up the wheel however hard you squeeze it... - Think old horseshoe brakes!!!...

They are Shimano Hydraulic Disc's.

*Edit, she has seen some VERY cold temperature whilst being here.. more than -17/18
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1978 MZ TS 250 1 Supa 5
1992 yamaha fzr1000 exup
1998 aprilia af1 sintesi

swampy · World Chat Champion Joined: 04 Aug 2004 Karma :

Brake, brake, fucking bbbrrrraaaaakkkkkkkeeeeeeee
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"I hate to advocate drugs, alcohol, violence or insanity to anyone, but they've always worked for me." Hunter S Thompson
"Faster, faster, faster, until the thrill of speed overcomes the fear of death..." Hunter S Thompson

MinhDinh · World Chat Champion Joined: 01 Jan 2005 Karma :

If they are Hydraulic then check the oil.

Perhaps the cold temp has affected that.

Squeekiness comes and goes I find on disc brakes.
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Hit the G spot. Wink

Jenks · World Chat Champion Joined: 22 May 2006 Karma :

checked the fluid. upto the max, and looks new still. doesnt seem to be a problem. (Just by looking)

Maybe - have the pads gone bad from the journey?
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1978 MZ TS 250 1 Supa 5
1992 yamaha fzr1000 exup
1998 aprilia af1 sintesi

geko · Derestricted Danger Joined: 03 Aug 2010 Karma :

Are the pistons moving on both sides of the caliper, or has one seized?

Have you had the pads out, give them a clean and a rub with some fine sandpaper.

Jenks · World Chat Champion Joined: 22 May 2006 Karma :

geko · Derestricted Danger Joined: 03 Aug 2010 Karma :

I avoid any kind of grease around the brake/pad. They don't generate enough heat to burn it off if any gets on them and even oily fingers can affect the brake.

I just use a bit of Wurth Brake & Chain Cleaner spray that I have for the motorbike. Drop the wheel out, clean the disk with it. Take the pads out, spray it on them and give them a light rub with sandpaper and rinse them off with it.

I've never had a seized piston on a bicycle disk brake but I imaging if one did seize it wouldn't be too clever because neither the caliper or the disc float, it relies on the pistons pusing from both sides.

Jenks · World Chat Champion Joined: 22 May 2006 Karma :

Well its fixed.. i had the pads out, and sanded them back abit, cleaned the disk and still the same, both pistons were fine.. Decided to bleed it..

Got no pressure at all, did it again, no pressure, screwed the cap back on the reservoir, and voila, pressure.. and its back in full force!! thanks chaps.
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1978 MZ TS 250 1 Supa 5
1992 yamaha fzr1000 exup
1998 aprilia af1 sintesi