Pushing a piston too far back?

jude436826

Hey there,

So I've got a bike with sram rival hrd, I've got some play in the lever, so I thought it must be a sticking piston, I then proceeded to push out the pistons slightly, then push them back in, I pushed the pistons ever so slightly back in more than flush with the caliper. I then put the pads and wheel back in to find that the right piston was moving less but the left piston wasn't moving in at all. I then proceeded to prevent the right piston moving in and squeeze the lever. Now the pistons move in but not enough to properly contact the rotor, there is also a lot of more of lever play. What could be causing this? And how could I go about fixing it if possible. Keep in mind I work at a bike shop. My guess would be that I"ve allowed a lot of air into the system and it needs to be bled.

Cheers

oxoman

Sounds like it's going to need bleeding assuming that you've not damaged the pistons or seals.

pilot_pete

You may have squeezed (one) piston out too far and allowed air in. I’d clean them with cotton buds and isopropyl alcohol before re-seating them, and then bleeding the system again with them fully back in the caliper. Once that is done, check them to ensure they both move freely and equally (being careful not to pop a piston out fully again whilst operating the lever with the wheel out or a piston spacer inserted). See how you go then.

PP