[COLVERT]

Originally Posted by Typhoon190

I was under the impression that putting fluid through the master cylinder 'the wrong' way could flip the seals if too much pressure was behind it. I've always taken care moving the caliper pistons back when replacing pads, as the 'proper' way is to allow the fluid out of the the bleed valve I thought?

Does ignition on make the ABS modulator open circuit, or does the engine need to be running? Thanks.

If the folk that keep this old wives tale alive thought about it would they think the seals would flip if you braked hard !!!!

As I said in the previous post the circuit through the master cylinder is OPEN CIRCUIT at rest. The piston moves back PAST the filler hole from the reservoir. This is how the fluid in the master cylinder is automatically topped up.

This through-hole is closed off as the piston moves forward under braking.---