Brake pedal ratio question

Is this correct?

From what I know about pedal ratio it is.

Ratio is: The long distance divided by the short distance.
In that picture, the short arm goes off at a slight angle, so maybe it's more like an inch and 1/8th = 1.125, if you measure actual center to center.
5.75" and 1" would be 5.75:1
5.75" and 1.125" would be 5.11
That 1/8th of an inch makes a big difference when the long arm is that short.

You can't necessarily go by the total length for pedal ratio for the above reason, and because the short distance can also be on the same arm as the long distance. Like this one: http://www.firstclassbrakes.com.au/wp-content/uploads/2014/02/brakepedal.jpg

6:1 is what I've always heard so that's not too far off.....

Adding a little length on the long arm will enable you to fudge a little on leverage when running manual brakes. I believe 6 to 1 is about average and small changes can make a big difference.

6 to 1 or 7 to 1 is considered "ideal", but I have gotten by with 5 to 1 in a tight situation. On a light car (under 2,000 pounds) it isn't as critical as on a 4,000 pounder.

Don

Also depends on whether you are doing power or non power brakes...

The master cyl bore makes a big difference also. In our builds and master assemblys we use a 1 1/8" bore with a 7:1 ratio. The big bore puts out a lot more fluid than a 1" bore and the longer ratio, make it easier to get pressure.

RPM said:

The master cyl bore makes a big difference also. In our builds and master assemblys we use a 1 1/8" bore with a 7:1 ratio. The big bore puts out a lot more fluid than a 1" bore and the longer ratio, make it easier to get pressure.

Click to expand...

Very true, the bore makes a huge difference. However, pressure = force divided by area. That means that the larger the area is, the lower the pressure is.
P=F/A
Larger bore = more volume, lower pressure.