Hi Folks,

So how does the rust form that makes brake caliper pistons freeze up?

The reason I ask is that I had that happen in both of my rear calipers well before the pads or rotors wore out. Both calipers had the inboard piston freeze in the open position.

Is this mainly because the car is parked outside and subject to the elements or is it because of water in the brake fluid?

Curious minds need to know to help prevent this from happening again.

Bert