Most of us rarely think about brake and fuel lines, especially the hard steel ones. We make sure that the rubber flex hoses are in good shape, blowing out a rubber line could mean disaster; but the only time the hard lines get any attention is when you bungle up the fitting and have to replace it. What you may not realize is that lurking inside that hard line may be years of rust and corrosion.
Have you ever noticed how old cars always have really dark brake fluid? Unlike all the other fluids, brake fluid rarely gets changed, and that actually creates a little bit of a problem. Most brake fluid (DOT 3 and DOT 4) is alcohol based, more specifically Glycol-Ether. Being alcohol based, these fluids are hydrophilic, meaning they attract and absorb water. Over time, the moisture begins to rust the inside of the steel hard lines, turning the fluid dark. The contaminants from the rusty lines wear out other components faster and diminishes the fluid’s ability to resist boiling. Changing the fluid is just another part of proper maintenance, especially on a car that has been sitting for a long time.
The fuel lines have a similar problem, particularly with Ethanol blend fuel. If you drive a modern car (less than 20 years old), you won’t have a problem with running 10% Ethanol blended fuel, but we are not talking about new cars here. Our beloved classics have a few things going against them in terms of E10 fuel. Just like alcohol based brake fluid, ethanol fuel is hydrophilic. Combine the water absorption with the corrosive nature of ethanol, and the protective linings in the gas tank and mild steel fuel lines are in trouble. Fortunately, the fuel in the lines doesn’t remain static nearly as long as brake fluid, but over time, the effects of corrosion become evident.
Replacing the entire hard line system is a large undertaking, but the benefits go beyond safety. Old, rusty and crusty lines don’t look very good against nice clean paint. This is precisely why we decided to replace all of the hard lines on this 1967 Corvette project. When we finally got back to it, the original lines really looked bad compared to the restored frame and custom suspension. Not to mention the fact that they showed signs of previous repairs. They had to go.
To ensure the new lines stayed sharp, we placed a call to The Right Stuff and ordered a full set of stainless steel brake lines and fuel lines. Even though the brakes on the Corvette are aftermarket upgrades from SSBC, the factory hard line locations still work. With that in mind, we opted for pre-bent lines instead of bending our own. Pre-bent lines eliminate the guesswork and difficulty of bending and flaring your own lines. With the pre-bent lines, the entire replacement job took less than a day. If we had bent and flared our own lines, this would have taken several days, especially with stainless steel, because it is much harder to bend and flare compared to mild steel.
While most of the time the lines will arrive at your door perfect, ready for install, there is some room for error on these things. The long lines, such as the front-to-rear lines, are typically rolled in half in order to facilitate shipping. This long gentle turn is easily straightened, just make sure you unroll it slow and easy, you don’t want to kink it. The key to installing new hard lines is to take it one section at a time. If you can avoid removing all of the lines at once, you can match each line and install them as you go. Some vehicles will require shipping your old lines to the manufacturer to be copied, so it may not be possible for everybody. In this case, take a lot of pictures and label each line to match tags you place on the car so that you don’t struggle with placing the new lines.
A final note on brake fluid: if you take the time to replace the lines, now is a great time to upgrade to DOT 5 silicone-based brake fluid. This will eliminate the hydrophilic alcohol fluid and silicone fluid lasts much longer, as well as being better in all facets of use. There are two caveats for DOT 5 fluid. First, all components must be new, the benefits of DOT 5 fluid are negated with even a small amount of DOT 3 or DOT 4 fluid mixed in. Secondly, DOT 5 fluid aerates easily and traps air. This means you need to let the bottle settle before adding it to the master cylinder and pour it slowly. Other than that, it is much better than the lower grade (DOT 3 & 4) fluids.