Disc Brake Help Please: Pistons won't retract fully

Hi all,

I have just put some new pads in my Formula R1’s but can’t retract the pistons far enough to give clearance between the new pads and disc.

Individually, each piston retracts fully but then when I go to push back the second piston the first pops out again.

I have tried to push both together but no luck. I have also tried pumping the pistons out a little with the brake lever and then pushing back in and repeated a few times in case the seals are just a little sticky- but again no luck.

The only think I can think is that there may be too much fluid in the system but they were fine on the last set of new pads and I haven’t bled them or messed with them since.

Am I missing something simple? What can I do to get both pistons retracting fully? Bleed?

Many thanks in advance for your wisdom 🙂

DanW

It does sound like too much fluid Open the bleed valve ad push the pistons back catching the bit of fluid that will come out

where did you get the pads from?

iirc some new pads* come up thicker than others, removing some hydraulic fluid might fix it

*this is going back a while now, cant remember the pad manufacturer or the brake brand that it particularly affected, a ‘way back when’ search on here might shed some more light

The original pads were the ones that came stock on the R1’s. New pads are Formula too but I guess the new pads may be slightly thicker. It’s the only thing I can think would change and prevent new pads fitting.

Strange thing though that the front brake is fine and just the rear causing trouble 😕

I had the same issue with my formula oros. Bleeding them sorted it.

Great, thanks for the help guys. I thought this was probably the solution but wanted to check I hadn’t missed something stupid first.

Ta! 😀