Re: Increasing front brake hose size opinions
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Brake pressure is a function of the caliper pistons resistance to movement, not the resistance of the lines. I think the main reasons manufacturers use small lines is because of cost and a smaller line is easier to route, not to create pressure in the system, and since there is very little flow in a brake system, a larger line is not needed. In short, you will be ok.
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Line size doesn't matter... it's the piston size on each end of the line.
I think they use small lines because then they can get more fluid displacement and get fluid out of the hot caliper. I could just be imagining this too.
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Tube & hose size does matter, a LOT! In steel tubing there is almost 2.5 square inches more surface area per foot with -4 or 1/4" tubing over -3 or 3/16" tubing. It is nearly 1/3 of another front caliper piston's area. That's a lot more surface area that will deflect. Deflection = mushy pedal. Put your hand on your rubber brakes hose and have a buddy stand on the brake pedal. That should show you that small is good. Going too far and trying 1/8 will not flow enough and cause a delay in brake application.
Don't use -4 for brakes in passenger vehicles, it's OK for hyd clutches. Bigger trucks, like 5 tons, use 1/4" hoses b/c of the large wheel cylinder volume.