had a bit of work done on my brakes a few weeks ago, including replacing the rear cylinder. Yesterday I did my usual drive through to my mates, doing 60 coming up to a roundabout, braked, braked a bit more with the intention of just slowing down, then a car approached from the right and I had to brake hard - the pedal just sunk to the floor, and the brakes seemed to release (thankfully that car had turned off to go the way i came by this point).
Any ideas whats happening? Ive thought it could be air in the system, but havent had first hand experience of it happening before, so couldnt say to be honest. Other possibility was a brake line expanding under braking?
Anyone?