I need to make some new brake lines..........on my 71 right under the master cylnder both brake lines make 2 loops before droping down into the porpotioning valve........why are the loops there...maybe to allow for vibration and provide a liitle give.....I'm wondering if I can eliminate them as it seems it would be kind of dificult to recreate...

 

Cars and trucks bend and flex as you drive. Many trucks have a frame that supports the body. The body is attached to the frame by rubber mounts, so there can be a lot of motion between the body and the frame. The master cylinder is attached to the body while some of the other brake components are attached to the frame. Also, when you step on the brake pedal, you flex the firewall of your car, moving the master cylinder but not the other components in the brakes.

A car is not always built with perfect accuracy. On one car the distance from the master cylinder to the anti-lock brake system pump will be slightly different from that on another. The extra flexibility added to the brake lines allows cars to be assembled even though they are slightly different from one another.

If the lines were short and straight, the motion of the car would eventually crack the brake lines; the continual flexing would fatigue the metal and eventually break it, just the way a spoon bent back and forth repeatedly will eventually break. By forming the brake line into a coil, the flexing in any one section is very small, and so puts almost no strain on the line.

 

All true! I would like to add that you can find pre-flared sections of tubing with the correct fittings at both ends that are made in many lengths. Get one several inches longer than the exact distance. The nice thing about these is that they are machine flared and have little to no discrepancy to the qualtiy of the flare. With these, you are less likely to have leaks or make mistakes that will frustrate you. They are also CHEAP.

you can easily bend double wall tubing around a floorjack handle for nice looking loops. They are easier to do than they look.

Buy a practice piece and get used to handling the stuff. Your new lines will look and fit great, just take your time.

 

To get those nice loops, wrap your brake line around a FULL
soda or beer can or a glass bottle.
Makes almost the same size loop

 

Use a full beer can then you have easy asccess to a refreshment to admire the job with when you are done

 

Also, there is some physics reason for doing it from a hydraulic viewpoint because it drops pressure before a joint or something like that.

 

Always wondered about that myself...

 

From a hydraulics standpoint, it make no difference actually. If there is no air in the line, there is no "compressable" fluid in the line.

So Force (F), times the Area (A) of the piston, is equal to Pressure (P) or... FxA=P These numbers are non variable within a fixed system.

When you push on one end of the system, since there is no way the fluid can be compressed, it must transfer that pressure equally in all directions.....since the other cylinder is not in a fixed spot, it will move, allowing the pressure to be eleviated.

THis is the simplest description. The coils are there for flexing, fudge-factor, and a classic look. The newer systems will often just have a "U" in the line or flexible lines. Those who prefere the old-school hotrodder look do the coils.