[Ron Sutton]

Hi Josh,

Originally Posted by BANKO

Another thing I noticed on your charts is an assumed static line pressure of 499psi for 7/8" MC and 679psi for 3/4" MC, can you speak to the what is an expected maximum line pressure in a manual setup.
Just to be clear ... I did not input that line pressure. That is an actual calculation of the line pressure with 100# of force from the driver's braking foot ... into a 6-1 pedal ... with those specific master cylinders.

I don't ever manually input line pressures into my calcs. I always calculate them. I use 100# of force from the driver's braking foot "most of the time" ... because for most adult males I have found that number to be representative of the driver pressing hard ... without tiring his leg out over the course of a race.

I have not performed calc's with "panic stop" level of pressures. But I know it can easily be double & more, because I see it when we're testing pressure at the calipers.

Using 100# is a good baseline starting point, but in the real world of racing, if I'm working with a driver long term, we're tailoring the brake system to him or her.

I've had 12 year old phenoms that weigh 74# body weight, so I had to "up" the brake system for them with more pedal ratio, smaller master cylinders and/or more aggressive brake pads.

Same with some bad ass female drivers I've had. Jessica Clark won two USAC Midget Championships & a NASCAR Modified race with us. She weighed 115 pounds. You don't want the driver to have to overexert themselves to achieve optimum braking force. Tiring them out over a race doesn't make sense.

On the other hand, you you don't want it too sensitive for them either. I had this crazy strong driver that could ... and did ... dead lift the front of a Midget (over 400#). We had to reduce the braking force for him, by switching to larger M/C's.

Make sense?


Some guys have mentioned measuring pressures of 800-1000psi. I assume this is primarily achieved by a greater input to the pedal rather than reducing MC size.
Yes.

Do you have numbers for the following driving styles: normal (non fatiguing pedal input), semi-aggressive pedal input (spirited driving / auto cross), aggressive pedal input (high speed track braking and panic stop situations).
Refer to my comments above.

As always thanks for your wealth of knowledge and willingness to educate us!

No worries.