Pots, Pistons, and More...
Subaru, in an attempt to meet a targeted
price point for the US, opted to give us two pot or two piston
calipers for the front disc brakes. Elsewhere in the world,
Subaru gave WRX owners four piston/pot front brakes. We also
received single piston rear brakes while those WRX's in Japan
and Britain were granted dual pistons.
A brake caliper squeezes a brake pad on
either side of the rotor. A single piston caliper only has
a single point on which the pad?and hence the rotor?where
pressure is applied. A two-piston/pot caliper has two points
where pressure is applied to the brake pad. A four-pot setup
has four points?and a six pot has six.
The theory is "the more 'pots', the
better". With more pressure points spread along the brake
pad, the force can vary along its distance allowing for more
So, in theory, the more pots, the better
the braking system "potential". Other factors come
into play such as un-sprung weight of calipers and/or rotors,
inadequate master cylinder, improper calibration of the pistons,
brake pads, rotor size, etc.
In other words, just throwing big brakes
on your ride doesn't guarantee improved acceleration/deceleration.
However, tuned properly, you can tame your WRX's power better
than you ever thought possible.