In the statement above you contradicted yourself. First there is negligible flow, then there is no flow. The flow is equal to the piston size in your master x how far the cylinder in the master is pressed. That fluid has to go somewhere, and its not on the ground......I hope.
Back to topic.
So that I understand what you are saying, the smaller line will not allow the pedal to move as far because there is less deflection in the length of the line when the pedal is pressed NOT that the smaller line has less fluid within it(which is true, but because it is a closed system, the line is full and fluid cannot be compressed(for this argument) so the pedal does not move as far)? How much less travel 1/8"? If the above is true, I cannot see the line swelling/deflecting/expanding to the point that you will ever notice it on the pedal.

I first said negligible to be specific. In an engineering sense, it is none. That is why I reverted to saying none. It saves time, this is common. However I see it has now cost another reply. So it didn't save any time in this case.

The pads float approx 0.010" from the rotor. At that distance you are talking less than 0.25 in^3 of fluid moved for the front brakes, and less for the rears. Then you will need to flow more all the compliance in the system. But overall it is not a lot. You are talking ~3" of fluid movement in a 3/16" front brake line.

I tend to agree that it will probably not be noticeable. But I love the good pedal feel of SOME modern cars and am willing to try things to get that feel. Hence the thread. This project is a science experiment and I am ok with that.

A secondary benefit is 3/16" is a much more convenient size to work with. It allows me to do a cleaner install on my car.

John

Remember most modern cars have TWO 3/16 lines running to the rear (from the ESC module under the hood), they also tend to have cross linked brakes (the not crap ones anyways)... not one 3/16 line that then splits into two 3/16 lines at the rear end. Two 3/16 lines is roughly the same cross section as one 1/4.

Old cars had one 1/4 line that splits into two 3/16 at the rear... Again cross section 1/4 ~ 2 X 3/16.

Running one 3/16 to the rear is not at all mimicking modern cars, it is halving them. If you want to mimick a modern car at least run two 3/16 lines to the rear like they do.

And yet the master still only has one 3/16" or metric similar line coming off of it that splits at the prop valve.

If a single 3/16" is big enough for one corner of the front brakes with a combined piston area of 9.8 in^2 then it will be just fine for the combined rears with a combined piston area of 8.8 in^2

There are not 2 lines in modern cars for FLOW, it is there for redundancy. It only adds more compliance to the system.

some guys get it...some dont..