BRAKING NEWS: A Closer Look into Brake Caliper Pistons
There are several factors at play when it comes to stopping your Ford Truck. These range from pad friction material, rotor material, suspension design, tire traction, and more.
We’re looking at brake calipers and how they impact stopping your truck. It’s a very important and sometimes misunderstood portion of the brake system, so let’s take a look at those pistons.
Brake caliper pistons, also sometimes referred to as “pots”, are the parts that put the force of the brake hydraulics into the piston pads to create the friction and heat forces to stop your vehicle. Pistons can be made of chrome-plated steel, aluminum, or phenolic resin thermoset polymer.
Simply known as a phenolic piston, the material is a type of synthetic polymer made by phenol, or substituted phenol, with formaldehyde, or more simply it is a form of plastic. The result is a material that is less prone to heat, moisture, and the environment around it.
Piston counts range from one large or two pistons on a sliding caliper to multiple pistons on a fixed caliper. A larger piston will have more contact with the brake pads and will give more clamping force.
However, multiple pistons can also increase the clamping force in a much smaller package. There is also a trade-off in pedal effort in a large single piston over multiple pistons as the brake fluid volume required for the multiple pistons will be less than a larger single piston.
Then here are staggered pistons and the stagger of the piston bore sizes allows a pressure differential between the leading and trailing edge of the caliper. So, the trailing edge piston will be larger than the leading edge piston for taper wear as there is a buildup of incandescent materials and debris that gets trapped between the pad and rotor. There is more pressure at the larger piston and forces the pistons to close in a way to prevent taper wear on the pad.
Finally, there is the design of the caliper and how it mounts. There is the Rigid Mount or the Floating Mount. Floating mount calipers slide on their brackets and self-adjust as the pads wear.
This is the type of caliper you see on your Fords most of the time. Rigid mount calipers do not move at all, but will not flex as much as the floating caliper for better brake performance. You’ll read this and may think of Brembo’s Monoblock caliper, too, but that’s not quite the same. It is a very rigid design and that is made of a single piece of billet aluminum and is a rigid mount design.
Find tips on brakes and much more in our How-Tos section here.
