F-body brake booster ratio?
02-28-2016, 05:01 PM
#2
the booster working off engine vacuum I think is supposed to see at least 18" of vacuum. ballparking numbers call that 20" of vacuum. atmosphere is 30", so you're looking at 2/3 of atmospheric = 14.7 psi * 2/3 = around 10 psi of help.
I don't know the size/diameter of the booster, but pounds per square inch means if you got 10 psi of help from the atmosphere,
area = [pi * r^2] then
I don't know the size/diameter of the booster, but pounds per square inch means if you got 10 psi of help from the atmosphere,
area = [pi * r^2] then
Code:
booster diameter area force 7" 38" 380 lbs 8" 50" 500 lbs 9" 64" 640 lbs 10" 79" 790 lbs
02-29-2016, 09:12 AM
#4
I found a manual way to measure it below, but I was hoping to just find the ratio documented somewhere.
http://brakepower.com/help_abc_16_BAR_t.htm
http://brakepower.com/help_abc_16_BAR_t.htm
03-13-2016, 12:59 PM
#5
Do you think this will get me in the ballpark?
Assuming vacuum=15, Baro=30, diameter=8 equals ~624lbs of force generated by the booster
If I already know the brake pedal output force is 255, then would the booster ratio be 625/255=2.5%?
Edit: Found this also:
https://grassrootsmotorsports.com/fo...r/18218/page1/
Assuming vacuum=15, Baro=30, diameter=8 equals ~624lbs of force generated by the booster
If I already know the brake pedal output force is 255, then would the booster ratio be 625/255=2.5%?
Edit: Found this also:
https://grassrootsmotorsports.com/fo...r/18218/page1/
Last edited by JimMueller; 03-13-2016 at 01:48 PM.
05-11-2016, 08:59 AM
#6
In case anyone looks for it in the future. I bought this:
The dial on the gauge was only 2", so we had to make a guess when the needle fell between the marks. Also, the gauge face is plastic, and exposure to the brake fluid caused portions of the face to become cloudy. An extension between the adapter and gauge along with a glass face would make things easier all around.
With 120lbs of brake pedal pressure and Wilwood brake proportioning valve set to full flow:
LF caliper: ~925psi
RF caliper: ~925psi
LR caliper: ~1125psi
RR caliper: ~1125psi
We measured multiple times. Going through the OEM 1998 F-body ABS block, the front ratio is ~8:1, the rear ratio is ~10:1.
The dial on the gauge was only 2", so we had to make a guess when the needle fell between the marks. Also, the gauge face is plastic, and exposure to the brake fluid caused portions of the face to become cloudy. An extension between the adapter and gauge along with a glass face would make things easier all around.
With 120lbs of brake pedal pressure and Wilwood brake proportioning valve set to full flow:
LF caliper: ~925psi
RF caliper: ~925psi
LR caliper: ~1125psi
RR caliper: ~1125psi
We measured multiple times. Going through the OEM 1998 F-body ABS block, the front ratio is ~8:1, the rear ratio is ~10:1.