We have probably all been there!! Maybe like me you always put it down to a slightly bent rotor or caliper not properly aligned. Maybe like me a slight caliper adjustement with 50% worn brake pads resolved the issue...well nearly...and who cares a bout a little bit of rubbing noise which is drowned out by the noise of the trail?
Well I recently renewed the pads and the problem became worse. It got me thinking why would the caliper go out of alignment in the first place? It was also noticeable looking at the old pads that wear was not even front to back.
I am dealing with a Code 4 pot caliper on the back brake. I removed the wheel and pulled the brake lever whilst watching the 4 pistons...obviously taking care I did not push one out. The root cause of my problem was immediately apparent. One piston moved out a great deal more than the other 3, 2 pistons moved out a little, 1 did not move hardly at all.
To resolve this I first of all whittled down a tyre lever so that it would fit snug between 2 of the pistons, holding them in. I held one further piston in by hand with another tyre lever. Then operated the brake lever to push out the remaining piston...it only moved fractionally. I used a tiny ( make up) brush dipped in DOT ( SRAM brakes) and cleaned/lubed the exposed part of the piston. Then pushed it back in. I repeated this several times until it moved much more freely each time exposing a bit more of the piston....cleaned/lubed again with DOT....pushed back in. Repeat. Repeat with each of the other pistons in turn. It took time but finally all pistons moved freely and the same amount. I sprayed IPO into the caliper and wiped it clean and re inserted the new pads. The caliper was then centred..............and absolutely no rubbing.
Cleaning/lubeing the pistons is now something I will do everytime I change pads!!
Well I recently renewed the pads and the problem became worse. It got me thinking why would the caliper go out of alignment in the first place? It was also noticeable looking at the old pads that wear was not even front to back.
I am dealing with a Code 4 pot caliper on the back brake. I removed the wheel and pulled the brake lever whilst watching the 4 pistons...obviously taking care I did not push one out. The root cause of my problem was immediately apparent. One piston moved out a great deal more than the other 3, 2 pistons moved out a little, 1 did not move hardly at all.
To resolve this I first of all whittled down a tyre lever so that it would fit snug between 2 of the pistons, holding them in. I held one further piston in by hand with another tyre lever. Then operated the brake lever to push out the remaining piston...it only moved fractionally. I used a tiny ( make up) brush dipped in DOT ( SRAM brakes) and cleaned/lubed the exposed part of the piston. Then pushed it back in. I repeated this several times until it moved much more freely each time exposing a bit more of the piston....cleaned/lubed again with DOT....pushed back in. Repeat. Repeat with each of the other pistons in turn. It took time but finally all pistons moved freely and the same amount. I sprayed IPO into the caliper and wiped it clean and re inserted the new pads. The caliper was then centred..............and absolutely no rubbing.
Cleaning/lubeing the pistons is now something I will do everytime I change pads!!
