Costa Tsimiklis wrote on Friday, December 24, 2010 - 01:49 am: Upto 100psi of pressure loss with floating calipers due to slide effect. More fluid is required to actuate the pistons due to their size.
As per my previous comments about the TT stock 2 pots the brake pad wear is exceptionally even. 100psi of pressure loss when the calipers might be producing 3000psi is minimal 3.3% but it does have a small effect. As I understand it before the caliper overcomes the opposing sliding slide ie the 100psi it will make contact with one side of the rotor and provide a very minimal braking force. This came sometimes been herd as noise under very light braking with floating calipers.
Costa Tsimiklis wrote on Friday, December 24, 2010 - 01:49 am:Fixed 4 pots, require less pressure and fluid to actuate
* Brake pressure is directly proportional to the torque force from the brake pedal, actuating the master cylinder piston. If more volume is required to shift single or dual piston floating calipers, theoretically upgrading to 4 pots should improve pedal response due to the lower pressure required to effectively actuate the caliper pistons
As a rule of thumb this is exactly the opposite when comparing 2 pot floating to 4 pot fixed calipers. The 4 pots require more fluid and have extended brake pedal travel in almost every compareable application in existance.
quoteauthor{Costa Tsimiklis,Friday, December 24, 2010 - 01:49 am,* Early travel brake force and/or effectiveness may be greater in a 4 pot setup, which has the feeling of 'improved' brakes. }
As per above this is not correct in just about every 2 float to 4 pot fixed comparable brake system.
As per the article copy/paste.
Costa Tsimiklis wrote on Friday, December 24, 2010 - 01:49 am:Because of this design you loose approximately 100 psi. 4 piston calipers squeeze from both sides and are fixed (don't float), so they (4 piston) do not require as much pressure.
Not true I think this isn't a clear statement. The pressure on both sides of the rotor applied by the caliper must be the same and this statement seems to be implying something different to this with a floating caliper. 4 pot fixed calipers can use less pressure combined with a larger rotor with more rotor torque to provide a similar braking force but this is not what I think they are implying in that statement.
Costa Tsimiklis wrote on Friday, December 24, 2010 - 01:49 am:The single piston caliper also requires more volume to work.
Not true infact in almost every compariable applicaiton in existance this is exactly the opposite.
Costa Tsimiklis wrote on Friday, December 24, 2010 - 01:49 am:The area of a 2 3/4" single piston caliper is 5.93 si VS the area of two (2) pistons on a 4 piston design of 3.53 square inches. (you only multiply by 2 piston to get the area because the other 2 pistons are being apply at the same time to squeeze the rotor, unlike the one piston design) anyway 5.93' si VS 3.53 is a big difference. Does the volume effect the braking? Yes,
This is again a mis leading statement implying that you only use 2 pistons of a 4 piston caliper to calculate the required volume of fluid also implying less pedal travel for a 4 pot setup compared with a 1 pot setup. This is totally incorrect.
As a general rule which is true for every application I have seen and is true for every compariable system the more pots the larger master cylinder bore is required.
Nissan 350z uses 1" bore for floating 2 pot calipers and 1"1/16' bore for the brembo 4 pots.
Supra uses 1" bore for floating 2 pot calipers calipers and 1"1/16' bore for the 4 pots.
As I said previously I have a set of LS400 calipers and rotors which I used on my own car but removed to go back to the stock 2 pots.
I would be more than happy to offer them to be used for a brake dyno test for comparison.
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