another disc brake query

avalanche

hi, anyone any ideas on disc brakes, im basically trying to avoid a trip to the bike shop where im sure they will tell me i need to replace something for what i am sure is an easy fix. my brakes are less thatn four months old and should be in good nick,

basically the rear pad (the side closest to the frame ) seems to rub off the rotor. When I look at it there is little or no clearance between the pad and the rotor - im not sure how you can get clearance here because the pad seems to have nowhere else to go. I have tried putting a card bettween the pad and the rotor, pressing the brakes and removing the card - this works as the rotor now moves freely,until i need to pull the brakes again and the rotors lock back in to the previous position,

i think this is slowing me down ( at least mentally ) and the constant squeal sound can wreck a good cycle.

anyone know how to fix this ? im using formula oro brakes,

thanks

rob1891

Sounds like a stuck piston, google for a good solution or do the following:

- take pads out
- put screw driver between pistons
- pull lever gently (pull too far and the pistons can pop out, screwdriver should prevent, aim to get the pistons out by about as much as they would extend when the pad is fully worn)
- drop dot fluid onto exposed piston body
- use screwdriver to gently lever pistons back in
- repeat

I've heard of bike shops doing quick fixes with regular oil, but I'd use dot fluid only. Your objective is to get the fluid to relubricate the seals around the pistons, which should happen from the internal side of the piston naturally, but sometimes they dry out for whatever reason.

Rob

edit: Your brakes use dot 4 hydraulic, use only dot 4 on them. dot 5.1 mixes with dot 4 fine, but you might as well stick to Formula's specs and use 4. Shimano use mineral oil, if you ever do this with other brakes be sure to use whatever hydraulic fluid is running in your brake lines.

avalanche

rob1891 wrote: »

Sounds like a stuck piston, google for a good solution or do the following:

- take pads out
- put screw driver between pistons
- pull lever gently (pull too far and the pistons can pop out, screwdriver should prevent, aim to get the pistons out by about as much as they would extend when the pad is fully worn)
- drop dot fluid onto exposed piston body
- use screwdriver to gently lever pistons back in
- repeat

I've heard of bike shops doing quick fixes with regular oil, but I'd use dot fluid only. Your objective is to get the fluid to relubricate the seals around the pistons, which should happen from the internal side of the piston naturally, but sometimes they dry out for whatever reason.

Rob

edit: Your brakes use dot 4 hydraulic, use only dot 4 on them. dot 5.1 mixes with dot 4 fine, but you might as well stick to Formula's specs and use 4. Shimano use mineral oil, if you ever do this with other brakes be sure to use whatever hydraulic fluid is running in your brake lines.

thanks very much rob, very helpful, i will give it a go later if i can pickup; some dot 4 otherwise it may be as well to leave it in for a service after all and get it done properly. seized piston sounds about right though. much appreciated.

kp29

most likely all u need to do is loosen off the two allen key bolts that keep the caliper in line with the pads( not the ones dat bolt to the frame) Once there loose pull the brake and whilst still holding the brake tighten de bolts back up.this will re-align the pads with the rotor. Really simple fix- nd most likely if you bring it to a shop they will just do it 4 you on the spot only takes two seconds:D