Brake line size

[92DSM89]

I have some brake line that i go for free but i'm pretty sure its bigger than stock. I have the adapters for the fittings so they will fit into the master cyliner, distribution block, and calipers.

Does the diameter of the the brake line effect pedal feel in any way? I've heard this argued both ways just wondering your guys opinion and knowledge...

 

[knochgoon24]

It shouldn't. Brake fluid should be incompressible.

 

[Calan]

I have some brake line that i go for free but i'm pretty sure its bigger than stock. I have the adapters for the fittings so they will fit into the master cyliner, distribution block, and calipers.

Does the diameter of the the brake line effect pedal feel in any way? I've heard this argued both ways just wondering your guys opinion and knowledge...

Theoretically it could...same pressure per square inch acting on the fluid at the caliper, but more square inches of cross sectional area to transfer that pressure. Realistically, I highly doubt if you would notice any difference at all unless they are like 1/4" ID lines from MC to piston; and even then the MC would probably be the limiting factor. Not to mention the fact that you would still be restricting it at every point you're adapting back down to factory ID.

But, I'd be a little concerned about more leak points with all those adapters.

 

[92DSM89]

Theoretically it could...same pressure per square inch acting on the fluid at the caliper, but more square inches of cross sectional area to transfer that pressure. Realistically, I highly doubt if you would notice any difference at all unless they are like 1/4" ID lines from MC to piston; and even then the MC would probably be the limiting factor.

But, I'd be concerned about more leak points with all those adapters.

Good Point I didn't think about more places of leaks but that right there might be reason enough to just run stock size.

But back to the theory, what differences would it make? Although I'm sure any difference is minimal i'm just curious.

 

[Calan]

But back to the theory, what differences would it make? Although I'm sure any difference is minimal i'm just curious.

It won't.

I wasn't exactly accurate in what I first said. The force changes at the piston as a function of pressure x area, but the actual pressure in the system would stay the same. Using a larger brake line size would really only be useful to help pads retract quicker (less restriction from fluid pressure loss as the MC relaxes)...but they could also create a slightly slower pedal response for the same reason.

But... you aren't changing the entire system, so once the lines are full and bled, you won't (shouldn't) see any difference at all.

At the very most, you might could come up with some additional frictional losses at the adapters or other very minor effects that are way out there in left field, if you really wanted to.

If you are interested in brake theory in general, this site has some very useful and interesting information.