Brake Piston Count Does Not Matter!
You may hear that having a higher piston count means better stopping power, or you may have seen calipers on the market with 6 or more pistons. Do not fall for the hype. It's just a gimmick some brake companies are hoping you'll fall for so you spend more money. Brake piston count doesn't matter! A 4-piston brake caliper typically performs as well or better than a 6 or more piston brake caliper.
Brake companies are trying to sell you on 'upgrading' to expensive 6 or more piston brake calipers, yet properly designed 4-piston calipers deliver the best combination of piston surface area, clamping force, and structural integrity. Many NASCAR, Sports Car, and NHRA cars use 4-piston calipers. If a 4-piston caliper can safely stop a 3500 pound Camaro when its chute fails at over 200 mph, or stand an out of control Monster Truck on its nose, then you probably don't need more than that for your vehicle.
Adding more pistons to a brake caliper means using smaller pistons, elongating the caliper, and adding holes in key stress locations of the caliper.
Using smaller pistons means the overall combined piston surface area actually decreases; resulting in less, not more, clamping force.
Elongating the caliper to accommodate 6 or more full-sized pistons means more flex in the caliper due to extended length. Caliper flex decreases clamping force and is the enemy of any brake system.
Adding more pistons of any size means boring more holes into the caliper body, which creates more flex.
To determine if this applies to an existing brake system, inspect the current brake pad wear. The worse the pad taper, the weaker the caliper. Deflection of the caliper is the sole cause of tapered pad wear! Even staggered piston bores can't prevent a weak caliper from tapering the pad.
TBM Brakes focuses on engineering outstanding 4-piston calipers that have a higher specific torque output and rigidity than any comparable 6-piston design. TBM Brake's range of optimized 4-piston calipers has proven to be the choice of champions and record breakers. In this case, more is not better.
It's simple science:
CLAMPING FORCE = PISTON SURFACE AREA ON 1 SIDE OF ROTOR x LINE PRESSURE
In a given location, you cannot put 6 round pistons with the same surface area as 4 pistons. The 6 pistons will always be smaller in overall surface area.
PISTON SURFACE AREA = PISTON RADIUS SQUARED X PI
PI is about 3.14159265359 Piston Radius is half of Piston Diameter
A small decrease in a piston's diameter equates to a relatively large decrease in the piston's surface area, so calipers really suffer when making room for more pistons.
Some manufacturers would have you believe that six pistons spread the force more evenly over the back of the pad. However, even if they did gain here (which they don't) the result of placing a piston in the key stress area of the body creates a far weaker caliper overall
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