[albanycobra]

Hi Paul
What it means is as the brake pads wear out the caliper pistons move further out. The problem is that there is nothing to protect the piston from dirt / corrosion / damage so when you put new pads in and push the pistons back the seal may get damaged or crap may just get under the seal and cause a failure.

Wilwood brake calipers are not road legal and state that on the box they come in. I have seen many cars regoed with them but like Mike says it's because the Engineer did not know or notice they have this problem.

I think Wilwood is a good brake caliper but not Road legal in Australia.