I recently heard a driver ask, “Why aren’t all brake lines made of stainless steel?”
The driver asking the question was just hit with a $800 repair bill to replace brake and fuel lines that ran a long a chassis rail on an 11 year old truck. Stainless steel is used on some vehicles, but the majority of vehicle brake and fuel lines are mild steel tubing that is called Bundy tubing. And the majority of replacement lines are Bundy tubing.
Bundy tubing is cheaper than stainless steel, but it is easier to bend, flare and install. It can also be coated to avoid corrosion and abrasions. But, the coating can flake off. Stainless steel will not not rust, but it is harder and not as forgiving as mild steel.
Bundy tube is a double-walled low-carbon steel tube. It is manufactured by rolling a copper-coated strip and heating to 720 degrees, while the seam resistance brazed by a process called a Bundy weld. The copper and brazing coat the inside and the tube is sealed. It was invented by Harry Bundy in Detroit. The first car to use it was the Ford Model T.
Over time, the brake fluid can corrode the copper and steel. If the brake fluid ages and the corrosion fighting chemicals break down, a system can corrode internally at a very fast rate. Some brake fluid tests measure the amount of copper ions in the fluid to determine the condition. Once the copper is gone, the mild steel goes fast.
Is there a was to make brake any fuel lines last longer? YES. First, replace your brake fluid to protect the internal part of the brake line. Second, move South. If not driving in the snow or on roads treated with salt and de-icers isn’t an option, you can take the time to wash your car regularly at a car wash with an undercarriage sprayer.