Disc Rubbing - How did this happen?
Plyphon
Posts: 433
Just wondering how this situation came about - i've fixed it allready just odd.
Went for a 2hr ride
Brakes working perfectly before and during.
Came home, brakes working perfectly.
Pressure washed the mud off bike about 15 minute after being home.
Front brake suddenly rubbing left pad.
I assumed it was water so let it dry off in the sun - but today it was still rubbing.
Went for a quick spin thought it might be grime - nah, still rubbing.
so I just re-centred it and it works perfectly - just wondering if anyone could guess what caused my pad (or rotor) to shift over the half mm or so it took to rub the pad? (To clear up, it was a 100% rub rather than the "swiiish-swiiish" of a wobbly rotor).
cheers
Went for a 2hr ride
Brakes working perfectly before and during.
Came home, brakes working perfectly.
Pressure washed the mud off bike about 15 minute after being home.
Front brake suddenly rubbing left pad.
I assumed it was water so let it dry off in the sun - but today it was still rubbing.
Went for a quick spin thought it might be grime - nah, still rubbing.
so I just re-centred it and it works perfectly - just wondering if anyone could guess what caused my pad (or rotor) to shift over the half mm or so it took to rub the pad? (To clear up, it was a 100% rub rather than the "swiiish-swiiish" of a wobbly rotor).
cheers
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Comments
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Sticky piston. Take the wheel out and check both pads are moving evenly when you brake - just a mm or so, so you don't pop the pistons out.I don't do smileys.
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools0 -
ill give that a go tomorrow, whats the cure for a sticky piston?0
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actually now I think about it the bike has a free service coming up - just gonna let them deal with it haha, cheers!0
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I'd say it's more a bedding in issue then.0
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Had exactly the same thing. Water has got into the system and created too much pressure that's why the piston comes out slightly. I re bled mine and all was fine after0
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So assuming your right, your happy to ride the bike with water where brake fluid (DOT or mineral) should be, IF (and I doubt it) water got in, then you'd have to completely flush the fluid to get rid of it.Frosticles wrote:Had exactly the same thing. Water has got into the system and created too much pressure that's why the piston comes out slightly. I re bled mine and all was fine afterCurrently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0 -
The Beginner wrote:
So assuming your right, your happy to ride the bike with water where brake fluid (DOT or mineral) should be, IF (and I doubt it) water got in, then you'd have to completely flush the fluid to get rid of it.Frosticles wrote:Had exactly the same thing. Water has got into the system and created too much pressure that's why the piston comes out slightly. I re bled mine and all was fine after
I didn't think it was water ingress either. But after it was jet washed the brake started rubbing. I took the brake off, removed the pads and pushed both the pistons back. One then slowly started to push out about a couple of mm. I pushed the pistons back again and undid the bleed screw. Very small amount of fluid was released and piston then stayed retracted. Bled the whole brake replacing all the fluid. Now perfect again. (elixir 7's)
I will guarantee all you need to do is re bleed the brake.0 -
Bleeding gets air out of the system. If there's no air, there's no point in bleeding.I don't do smileys.
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools0 -
cooldad wrote:Bleeding gets air out of the system. If there's no air, there's no point in bleeding.
Also condensation..............................................
Just bleed it. It will be fine!!!!!!!!!!!0 -
Rubbish - if the lever is squidgy, or travels to the bar, bleeding might be needed. For rubbing or a sticky piston it isn't.
OP now says they work perfectly so they don't need bleeding.I don't do smileys.
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools0 -
cooldad wrote:Rubbish - if the lever is squidgy, or travels to the bar, bleeding might be needed. For rubbing or a sticky piston it isn't.
OP now says they work perfectly so they don't need bleeding.
Ok then I'm Lying :roll: I don't care what you say seeing as you know it all!!
I was trying to explain that I had Exactly the same problem after jet washing (Stupidly) the brakes!!!!
I will now refrain from trying to offer advice seeing as the know all police always know better!0 -
I didn't say you were lying. But if he has managed to get water inside the system, which I doubt, they should have a flush and new fluid. But if they are working fine, they don't need bleeding. That's all.I don't do smileys.
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools0 -
How does jet washing your bike equal getting water in the brake lines? Very odd.
I bet there was nothing wrong the brakes, just needed to bed in, so the pistons find their normal position.0 -
woah now!
I don't think it was a bedding issue - I have ridden the bike plenty (even done a 2hr ride the day before no issues) so i think everything would have bedded in by now?
I didn't exactly pressure wash the brakes... never directly, but we did do the forks so you know maybe some hit the calliper hard.
the brake works fine now, and feels the same, just came out of align somehow (either through the pad moving due to X Y Z reason or something else) - all i had to do was manually realign it.
I will add the "undo calliper mount bolts, squeeze brake and redo" method didn't work - I had to manually hold it while tightening - which leaves me to believe one pad is travelling more than the other.
I'll mention it to the LBS on Thursday and see if the address it in the service.
But as I've said the brake still feels 100% the same and stops me on a dime.0 -
And there would have been no problem at all if any of you had cable disc brakes
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Pressure washing more likely got grime behind the pad ect..0
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Chunkers1980 wrote:Pressure washing more likely got grime behind the pad ect..
yeh beginning to think its as simple as that. Might take it apart tomorrow after work.0 -
How did condensation get int a sealed system?Frosticles wrote:cooldad wrote:Bleeding gets air out of the system. If there's no air, there's no point in bleeding.
Also condensation..............................................
Just bleed it. It will be fine!!!!!!!!!!!
Bleeding is rarely the answer, but often used wrongly, in many cases hiding other issues.Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0 -
And moreso if it did manage to, it would not cause the lever to feel spongy, it would just boil over at lower temps!The Beginner wrote:
How did condensation get int a sealed system?Frosticles wrote:cooldad wrote:Bleeding gets air out of the system. If there's no air, there's no point in bleeding.
Also condensation..............................................
Just bleed it. It will be fine!!!!!!!!!!!0 -
Only if in the calliper, the lever never gets hot enough.......Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0
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Well obviously yes....The Beginner wrote:Only if in the calliper, the lever never gets hot enough.......0 -
Bleeding wont get rid of condensation, The water would be absorbed by the brake fluid as it is hygroscopic, This is why its advised brake fluid in cars should be changed every 2 years.
This is also why on fluid bottles you see 'Dry' and 'Wet' boiling points.
So no, bleeding the brakes would not in any way clear condensation. Unless you completely flushed/drained the old fluid out and re-filled with fresh0
