Brake plumbing / fuel plumbing question


Is using bigger tubing a problem? is supplying more volume an issue I guess is a better way to state the question.

I will be plumbing my rear end housing and have access to tubing but its not the size I keep seeing or getting told to use it would be .250 tubing vs .1875 tubing. So essentially id be supplying more volume to the caliper inlet than is needed but I do not think this is bad. Is my thought process correct?

Same goes for fuel lines. is it bad to run larger lines that end up reducing down say at the fuel rail or a regulator or even at the pump.



Well-Known Member
Very little drawbacks to bigger tubing.
-increased weight
-increased cost

Both of these drawbacks are marginal IMO.

You won't see any loss of pressure or performance with larger tubing.


Well-Known Member
The tubing does nothing to increase pressure or volume or anything like that. The volume of brake fluid required to push the caliper piston comes from the master cylinder pushing incompressible fluid into a closed system. Your brake lines could be an inch in diameter and it would still work the same way.

Josh 8

Well-Known Member
But. Larger tubing will expand slightly more than smaller tubing. How much? I don’t know. That’s really an engineering equation.

It probably won’t make a difference. But it certainly won’t help.

It could make bleeding the air from the system a lot harder. Small diameter tubing pushes bubbles out well. Larger diameter tubing could have air lock in the top of loops that never come out and render the breaks spongy and useless.


New Member
Late to the game but might as well answer if anyone else looks. The difference in volumetric expansion is proportional to the difference in diameter. So a 1/2" tube has 267% more expansion than a 3/16" tube. While that seems like a lot, it ends up being pretty negligible because the expansion is so small to begin with. A 3/16" copper nickel tube at 2000 psi will only expand 0.06% while a 1/2" will expand 0.16%. So you might not feel the difference HOWEVER a 1/2" line will burst at 2000 psi where a 3/16" can handle over 4000 psi. I wouldn't go bigger than 3/8" and you shouldn't really feel a difference between 3/16" and 3/8" line. This does not apply top braided line