brakes sticking when lever is released

[Warren]

hi,
need some help quickly,
my front brake, when braking hard, brakes.
when i release the brake, it carries on braking hard.

if i use it lightly, there isnt a problem, only when braking hard.

when stationary with the wheel off the floor, the brake seems to be fine, no sticking

plenty of meat on the pads, brake fluid is topped up nicely.


will it be just the road crud causing the brake to stick like this ? or is it something more serious ? like seals need replacing ?


it was quite tricky when braking hard after an overtake, then the bike continued to brake til i was near enough at a stand still.

please help, cos im stuck 100 miles away from home with limited tools, and i dont really fancy riding it while the brake is playing up

[dirtydog]

I'd say your piston/s are sticking you'll need to at least clean them or more preferably strip and replace the seals

[jonboy]

Ideally you want to take the calipers off the forks and see if you can remove the pads and pump the pistons out a little (but not too much!) and clean them as I would think they're all gunged up and sticking badly.

If you're unable to do this then see if you can pour boiling (or very hot) water into the caliper to hopefully remove enough of the crud that's causing this problem, which will hopefully get you home.

Also check your brake lever. Undo the bolt that holds it on and make sure it's not all corroded and is sticking there too. I remember Sid Squid taking my lever off and greasing it - I couldn't believe the difference as it was sticking and notchy, and just this simple operation of a little grease (butter would do if you're stuck - but NOT in any Brandoesque sense :lol: ) made all the difference.


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[Warren]

just cleaned the calipars up, and put it back together,

they wernt that dirty, as i had cleaned them up about a month ago.

went out, and still got the same problem :(

it only ever happens when i brake hard though which is strange,


so im guessing its new brake seals i need ?

cheers for the replies so far though :)

[Well Oiled]

This happened on my lads SV and was caused by the seal getting dragged out of its groove and trapped between piston and bore. root cause was build up of aluminium salt type crap in the groove which pushed the seal out. Don't know if that's what's causing your problem, but be careful as it ended up with the brakes grabbing unexpectedly mid-corner and causing an off for my lad.

HTH Keith

[Blue_SV650S]

If it isn't the seals/callipers, then it could be a sticky master cylinder piston.

Pull the brake on hard and then release the leaver, check the master cylinder piston returns sharply and fully. A strip and clean of the master cylinder might be in of the order!!

[Warren]

This happened on my lads SV and was caused by the seal getting dragged out of its groove and trapped between piston and bore. root cause was build up of aluminium salt type crap in the groove which pushed the seal out. Don't know if that's what's causing your problem, but be careful as it ended up with the brakes grabbing unexpectedly mid-corner and causing an off for my lad.

HTH Keith

hhmmm - i was hoping it would be something more simple than that.

but it only happens when braking very hard, under normal braking its fine.

[RandyO]

I have found it a waste of time & money to fuss with calipers, I just replace mine with new ones

[jonboy]

Obviously a Lottery winner.


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[Warren]

just a question, is changing seals a pig of a job to do ?

or am i best getting the dealer to do it ?

(i deteste giving dealers my hard earned cash when i can quite easily do a job myself at only a fraction of a cost)

[Warren]

I have found it a waste of time & money to fuss with calipers, I just replace mine with new ones

why not go the whole hog and just replace the whole bike ?

:lol:

[Fuzz]

just a question, is changing seals a pig of a job to do ?

or am i best getting the dealer to do it ?

(i deteste giving dealers my hard earned cash when i can quite easily do a job myself at only a fraction of a cost)

Well I didn't get round to replacing the seals, but it's not a major headache to do. This coming from someone who hates brake systems. The pistons are the hardest thing to remove without damaging them :-dd but once they're out, replacing the seals is easy. Just make sure both pistons move equally when you pump the lever. I had them both come out to a point, then the pressure would only push on one before the fluid pushed past the dust seal, and I had to rock the pistons out the rest of the way with my hand. Not easy when it's encrusted and won't budge either way. That's how you end up doing things you know you shouldn't, and pressing a plier print into the end of the piston.

[jambo]

You may well be able to re-use the piston seals, if you use a spanner or similar to stop the piston that moves fastest so they both come out together, then strip and clean the caliper use hot water to clean the seals up, if they are still happy and round and have no cracks in them coat them in universal rubber grease and re-use them.

To avoid unfortunate incidents with marking a piston, if you do have to use a *little* pursuasion to get a piston out, use external circlip pliers to grab hold of the inside of the piston, or use a bit of rubber or cloth between pliers/mole grips and the piston itself.

Or you could just play the lottery and buy a completely unknown set of calipers and see if they happen to be any better than your current set :roll:

You've not mentioned testing Jonboy's theory, have you taken the brake lever off, cleaned and greased / oiled the pivot and lever to check they move smoothly?

[Warren]

i havent yet tried johnboys theory, but if i get time, i will do it this afternoon.

came home last nite and didnt have any problems with it - its just a bit disconcerning really.