BRAKE LINES and tech question

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BRAKE LINES and tech question

December 13, 2014, 11:14:55 AM

I suppose i could have / should have opened up my shop manuals and found my answer but i will be a tad lazy and ask here first.

I notice on our cars, the front driver caliper is tied directly to the master cylinder.

***all other brake actuation passes through the next downstream device called the proportioning valve.

Why?

This adds to my theory of why people find sticking or failing calipers on the passenger side much more early than on the drivers side.

With no engineering education to back up what i am going to say.......... I would think that you would want the front calipers to have equal length supply tubing and equal designs , not having one caliper with super short tubing home run to the master cyl while the front pass is much longer tubing plus the added prop valve it has to over come.

for some reason i remember a few years ago about people taking apart and modifying their prop valves,, there use to be a lot of threads on this topic and i cant exactly remember why.

BRAKE LINES and tech question

Reply #1 – December 13, 2014, 04:06:32 PM

People modded their prop valves because they swap in disc rears, which take more fluid volume to effectively work than drums. So the prop valve will need gutted and/or replaced with an adjustable unit.

And also, in regards to '87-'88 cars, the brake lines are rather different on the 3.8 cars compared to the 5.0 cars.

BRAKE LINES and tech question

Reply #2 – December 13, 2014, 10:05:13 PM

The lengths of the lines do not matter because the pressure has to build in both calipers to apply. As far as adding failure because of longer lines that is not true. The reason ford ran seperate lines to the master is because they did not tie them together on the frame. I always tie them together at the drivers side brake hose and run one line to the master for the front and one line for the rear. The Combo valve is used for system failure indication and proportioning for rear brake balance. The length of the lines make absolutely no difference in brake performance or wear conditions

BRAKE LINES and tech question

Reply #3 – December 14, 2014, 12:16:26 AM

I'll ask again

Why does the front driver caliper homerun to the master cylinder while the front passenger caliper goes through the proportioning valve

BRAKE LINES and tech question

Reply #4 – December 14, 2014, 08:42:59 AM

It makes no difference ford just did not want to bridge it on the frame. The port is the same on the master. So if you have a line break in the front system you loose both sides anyway and light the dash warning light or break failure light Ford does strange things sometimes, One or two lines is not required to go to the balance portion of the valve. As long as it sees a balance between front and rear the shuttle valve keeps the light off. By the way the balance valve when in fail mode sends out a ground to light the lamp

BRAKE LINES and tech question

Reply #5 – December 14, 2014, 09:21:02 AM

ok,
same situation but there is a spiral wound section of brake line like you did tom off a master cyl,,
why is the spiral needed?

I always understood that there are static losses in line length+ the qty of bends each time you bend a line, it reduces its ID and that is additive like resistors in series.

BRAKE LINES and tech question

Reply #6 – December 14, 2014, 01:29:38 PM

Hhydraulic lines are different from air running inside a pipe.

We run loops like that in solid cable line to add a section for flex due to heat and cold cycles.

BRAKE LINES and tech question

Reply #7 – December 14, 2014, 02:20:13 PM

Brake fluid doesn't compress, therefore a 6" line will take no less effort at the pedal than a 16' line. as long as you have quantity in the reservoir for the piston to draw enough fluid from during braking, the lines care not how big, long, or what their ID is.

But obviously, a garden hose will hold more fluid by volume than a steel brake line. But you don't see garden hoses used as brake lines..or, I'd hope not.

As for the coils on a brake line under the master, I'd always thought that had more to do with heat dissipation and vibration than anything else...

BRAKE LINES and tech question

Reply #8 – December 14, 2014, 05:25:44 PM

The coils are done for strain relief. The master actually moves when you hit the brakes. Are they necessary probably not but that is my mark when i do brake systems. Just little fancy foot work i guess.