Brake Lines @ Master

[84_chevy]

I'm going to be replacing the lines at the master cylinder and I have a quick question before I start.

I have noticed that the brake line that come from the master cylinder usually are spiraled several times before they route down to the proportioning value. Is there a added benefit in spiraling the lines like that or is it only done for appearances?

[k2rm]

I am not sure, but I believe it is to help prevent air bubbles from getting back into the master cylinder if air gets into the system. Air likes to collect in high spots. If air gets back into the master, bench bleeding is often needed which means you have to disconnect the lines and remove the master.

Its not required.

[84_chevy]

That kinda makes sence but for the line to be able to trap air bubbles from re-entering the master the spirals would have to be higher then the master. The line would have to go up and then spiral down for it to function that way. I always see the lines spiraling down so they would not be able to trap any air. Maybe people have forgotten the reason why the lines are installed that way and just add the spiral because everyone else Duz it that way without understanding why.
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[claytonisbob]

I always thought that was to give the lines a flex/vibration point since the master is mounted to the body which is isolated from the frame over the rubber body bushings. I think since most new cars are uni-body, they do not have/need this. Obviously there is little to no movement between the frame and body, but I would think vibrations could crack the brake lines over time if the line didn't have some sort of isolation.

I could be wrong, but that's what I always concluded. I didn't put a pigtail on my Chevelle, but I also have stiffer poly bushings.

[84_chevy]

I guess it's just strange that almost everyone installs the lines like that but no one has a definitive reason why. I'll follow suit and spiral the lines but I'd still like to understand why I'm doing it.
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[66shortwide]

spiraling the lines has absolutely nothing to do with air in the lines - in a hydraulic system air is bad no matter what. I was always told it was for vibration and body flex.

[gimmy 64]

it's for adding suspension to the lines so they don't brake. because they are mounted to body and frame and bend and twist at differant times.

[Rooster's 67]

Originally Posted by gimmy 64

it's for adding suspension to the lines so they don't brake. because they are mounted to body and frame and bend and twist at differant times.

Ding Ding Ding....winner.

The Spirals that are wound into the brake lines are there for flexing. If you were to plumb them without, you would run the risk of "work hardening" the brake line and causing the line to break/split.

you dont have to do spirals, you could always add in a section of flexible rubber line just like chassis to suspension.