# Brake Line Replacement Question



## Icefan71 (Apr 7, 2011)

I'm gonna replace the brake lines on my 72 Lemans w/ front disc, rear drums. I'll be bending them myself. I know, PITA, but much cheaper than buying pre-bent lines. My question is on the proportioning valves. Is that something that also needs to be replaced? They are very rusty on the outside. But I can clean them up if its just the outside. Don't know what the inside looks like. I don't hear too much about people replacing them on any vehicle. But if I'm gonna have all the brake lines off, I'd like to get everything done at once. I'll also be replacing both rear wheel cylinders.


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## Eric Animal (Oct 28, 2007)

IMHO...With all you are doing, replace them too.


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## pontiac (Mar 6, 2011)

if you are replacing the master as well, then yes. Otherwise, just clean it and be done with it. The new valves are not any better, just cleaner. If you can live with the old master, then the old valve will be just fine. If you are doing the new lines in stainless, the double flares are more difficult to make with hand tools. if just steel, then you should be okay. what about the lines from the master to the valve? Are you bending those as well? Different size tubing required.


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## Icefan71 (Apr 7, 2011)

Yes, I'm gonna replace the master cylinder too. I am aware that the brake lines are 2 different sizes. I believe they are 3/16 in front and 1/4 front to back. I'm going with steel not stainless. And I guess you guys convinced me. I might as well go for new valves. It only makes sense. Thanks for the input.


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## BearGFR (Aug 25, 2008)

Consider stainless. Normal brake fluid is corrosive and also "likes" water. Moisture in the lines leads to rust and that's the main cause of having to replace lines. Any other brake system components (proportioning valve, distribution block, cylinders, calipers) that are steel or iron inside will rust too. Stainless is more difficult to work with, especially flaring, because it work hardens quickly and will split/crack soon after. If you get the right kind of stainless it's a little easier to work with than most but is still trickier than plain steel. I got a full set of pre-bent stainless lines from Inline Tube - they also carry the "good" raw tubing for making your own.

Your call. I went with pre-bent stainless even though it's more expensive because I plan to keep my car forever and only wanted to do this job once. Steel lines would have eventually rusted and needed replacing again.

Bear


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## 66tempestGT (Nov 28, 2009)

mine are still holdind up after 45 years. when i replace them (whenever they start leaking) i expect to get another 45 or more.


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## Icefan71 (Apr 7, 2011)

Cost is my biggest reason for using regular steel and not stainless. I also figured this car is only gonna see warm weather and not much rain. My daily driver is a 94 Toyota Camry and that has its original brake lines with no signs of rust. My wife drives a 98 Expedition that the previous owner took to the beach and that also has no signs of rust on the brake lines. We had a Taurus that had bad brake lines only because they had a plastic cover on them that held water.


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## BearGFR (Aug 25, 2008)

Just to clarify, I'm talking about rust on the inside due to the nature of brake fluid and its affinity for water --- not rust on the outside. Some folks convert to silicone based brake fluid for this reason, but that too has its own set of problems.

Bear


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## pontiac (Mar 6, 2011)

water in brake fluid will only rust inside steel brake lines if there is oxygen (air) in the system. most if not all corrosion seen in brake fluid comes from air contact with the cast iron master cylinder, same place fluid gets water from, not in the steel brake lines. No way to avoid master from rusting, unless you have a master that is not cast iron. Failure on steel brake lines is usually from the outside in, not the other way around.


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