kcaalarcon

This is most likely a very stupid question but im going to shoot anyways. I have a 88 bird that originally had rear drum. Since then, I have swapped on a set of second gen cts-v brakes front and rear. I also have a wilwood 1 1/8 master. Now, I am trying to figure out the brake lines, front and rear. First question, should I leave the stock front lines the same size or make them smaller so they have higher pressure? second question, I should probly make my rear line off the master cylinder smaller because it was originally drum? I also have a 4th gen rear so that had disks. So after the T should I leave those lines the same size or also decrease their size?

Gregs_GSXR

just change out the spring inside the stock prop valve, and get new lines from Inlinetube.com then call it done.

I wouldn't go smaller. Brakes work on pressure and volume. Changing the line size smaller would slow the amount of fluid getting to the rear calipers.

kcaalarcon

Theoretically wouldn't it make the pressure higher?

Gregs_GSXR

Your right, but I would leave the line size alone and just change the spring.

kcaalarcon

Thank you for your thoughts. Does anyone else have any input they could contribute? Just want some different opinions on this?

RBob

iTrader: (1)

OK, you asked. As for line pressure, the diameter of the line doesn't matter. The psi at the rear of the line will be the same as the psi at the front of the line.

What the diameter of the line does affect is compliance. That is how much the line expands as the pressure goes up (1200 - 1400 psi). The larger diameter line will expand more causing a less effective pedal.

On the other hand (OTOH), drum brake systems use less pressure and more volume. Which is why there is a 1/4" (or 6 mm in metric) line run from the front of the car to the rear. The line needs to be large enough to move the volume of fluid that drum brakes require.

And with lower pressure the line doesn't expand as much.

To save cost GM used the 1/4" line for both disc and drum rear f-body's.

And that 1-1/8" MC may be too large. The line pressure is going to be too low for decent braking. Can make up for that via high friction pads.

Although, the larger diameter M/C will help with the rear pad knock-back.

RBob.

87350IROC

iTrader: (2)

Well said.

kcaalarcon

When I ordered the ms I kinda had my head up my a$$ so ill see how that goes once the car is on the road. 1 inch would probly be better suited than? And maybe downgrade to a slightly smaller rear line to the t?

kcaalarcon

Or I could probly get an ls1 master cylinder and that would work too?