Boxster brakes piston size question

[quint22cp]

Boxster brakes have different size pistons in the caliper.
Which piston is the leading, large or small ?
Is it the same for the back as the front ?

........dumb questions I know, but I don't want to fit them upside down.

[BertBeagle]

The following is true in every instance with brake calipers:

1. In every case the small piston is the leading piston. This means that as the car rolls forward the brake rotor rolls by the small caliper piston first. You may have to remove the bridge pipes and bleed screws and swap them end for end to achieve this set up.
2. When you have staggered pistons (two different piston sizes in the same 4 or more piston caliper) - you can, most times, convert a leading caliper to a trailing caliper. Worst case you will need a new bridge pipe.
3. When you have staggered pistons in a caliper - you can never convert a LH caliper to a RH caliper or vice versa.
4. Bleed screws always need to point up to facilitate bleeding the air from the system.
5. Some, but not all, Brembo calipers have an arrow on the side of the caliper. This arrow shows the rotation of the brake rotor through the caliper when the car is moving forward. With the caliper mounted as leading or trailing, the arrow must point in the direction of rotation of the rotor.

[V12man]

On Boxter brakes you will need to move the bleed screws to the other side of the front caliper if you are going to fit them as a leading caliper on your car - fairly simple - with the caliper off the vehicle, unscrew the bridge pipe and bleed screws, and swop them around to the other side of the caliper - then you are good to go to install them on the leading side of the wheel.

It's a bit messy - keep a cloth handy.

Guy