Quote:
Originally Posted by BRIAN
Kore...I was referring to a GM style single piston vs any say 4 piston,6piston etc type caliper. I may be wording this wrong but what I am getting at is there has to be some pressure required to actuate a single piston cyl before pressure is applied to the rotor? I am not talking cyl sizes. If you were to take two equal sized volume single vs multi piston calipers would there be a difference?
Theory is great but I have swapped wilwood 4 pistons onto a car that had GM singles and there was a difference. Was it piston bore size? Maybe?
Not arguing just looking for good info.
Thanks
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If I understand your first question correctly, yes, there is some pressure required to actuate the pistons and that pressure is basically whatever is required to overcome the friction in the system, both mechanical from the seals and the fluid. That said, those pressures are so low relative to the max system pressures, it's virtually zero for all practical purposes.
Two calipers with the same overall piston area, regardless of whether it's a 1-piston floating caliper or a 8-piston fixed caliper, will exert the same clamping force. The advantage to 4 and 6-piston calipers is that they allow you to run larger brake pads and better support the backing plates. Single piston calipers tend to bend the pads over the piston under severe use.
When you swapped to the Wilwood calipers from the single piston GM calipers, changes in rotor diameter, pad coefficient of friction, MC bore and pedal ratio are all part of the equation. Without more info, it would just be speculation as to what was the primary cause for improvement.
In my experience, most people rarely upgrade fully functional, good condition brakes with high-quality components. We wait until the rotors/caliper/pads/hoses are basically falling off the car and then decide it's time to upgrade. While it tends to make for a huge improvement in braking performance...so would have new OE brakes most of the time (and I'm not talking about the cheapest parts you can buy from a discount auto parts store).
This site is great for good info, good folks and some amazing cars.
Tobin
KORE3