Rick's Free Auto Repair Advice

Replace rusted brake line

How to replace rusted brake line

by Alex Steil

You can replace rusted brake lines yourself with an easily bendable brake line from S.U.R. & R. and an inverted flare tool. I’ll walk you through the entire process on a Subaru, but it’s the same on most cars and trucks. But first a background on the rusted Subaru brake line problem.

Why Subaru brake lines rust and leak

Subaru actually put some effort into preventing rusted brake lines. You’ll see some images below showing of how Subaru not only coated their brake lines with a vinyl coating, but also ran most of the line inside the vehicle to prevent it from contacting road splash.

The brake lines run from the master cylinder on the driver’s side to the ABS pump/valve assembly on the passenger side. From there, the lines goes through the firewall and down along the passenger side rocker panel towards the back seat.

subaru rusted brake lines underhood

subaru brake lines along rocker panel

Then they go through the floor pan under that back seat to a 4-port union under the vehicle.

Subaru brake line to back seat

Here’s where all the Subaru brake line rust problems start

Subaru brake line union rusted brake lines

Subaru stopped the vinyl coating about 1″ from the flare nut at the union and THAT’s where the brake lines rust. It’s a very tight spot and all four lines rust out right there.

Here’s how I fixed the Subaru rusted brake lines

I could have simply cut the old lines where they exit the vehicle under the back seat. But in a moment of sheer insanity, I thought it would be a great idea to replace one brake line in a single run from the union under the hood, through the firewall, along the rocker panel, down through the back seat floor pan and then down to the union under the vehicle. It’s doable and using the S.U.R.&R. copper/nickel brake line make bending very easy. But running the new brake line through the firewall wasn’t easy and I wouldn’t recommend it unless you have an extra full day and a full head of hair–because you’ll be pulling it all out by the end of the day. Hello Subaru, did you have to make several 90° bends inside the dual layer firewall before exiting into the engine compartment? Well, I did it.

I should have just cut the lines at the back seat, installed two double flare unions and run new line from that point.

Here’s a shot of the new S.U.R.&R. line going through the back seat floor pan and me cutting the other line.

cut old brake line in back seat

I used the Titan Tools #51535 Double Flaring Tool for 3/16″ brake line to make the double flares for the splice in the back seat area. It’s an OK tool for the money as long as you don’t mind fumbling around with multiple wrenches to clamp the line in place and then use a different wrench to make the flares. Here are the steps.
back seat brake line splice finished

Next, make the under body flares

This is where I used the S.U.R.&R. pistol grip flaring tool. It is SO much easier than the Titan Tool and it makes a better flare. First I clamped the brake line into the die. Then I inserted the S.U.R.&R. flaring tool with the inverting plug, squeezed the trigger a few times, then reversed the plug and made the final flare.

Here are the images.

setting tubing depth in SUR&R die
making final flare with SURR tool
completed flare

Now I was ready to bend the lines and screw into Subaru union

Here are the first two lines in place
replaced rusted subaru brake lines
And now all four lines have been replaced
replace rusted brake lines
While I was there, I also replace the flexible brake line hoses and the short brake line sections from the union to the hose. This was the only time I had to use a bending pliers. I made all the rest of the bends by hand without tools. That’s the beauty of the S.U.R.&R. product; it’s so easy to bend.
brake line hose

Rusted brake line cost

The shop quote for this job was a little over $1,100. Since I was stupid and wanted to replace one brake line from front to rear, I bought a 50-ft. roll of S.U.R.&R. Ultrabend brake line. But I could have done the splicing and rear line replacements with just a $25-ft. roll.

I bought the Titan Flaring tool (around $50) and S.U.R.&R. lent me their tool  (Thanks S.U.R.&R.). But even if I had purchased the S.U.R.&R. piston grip tool kit for around $300, my total cost on the brake line replacement would have been less than $400, including all new flare fittings. NOTE: Do NOT reuse the old flare fittings. Why? Because the rust has already compromised the anti-corrosion coating. Don’t be a cheapskate, new fittings are only about $2-each.

FTC NOTE: Aside from lending me their flaring tool, S.U.R.&R. didn’t provide any free goods for this story and they did not pay me to write this post. I did not give S.U.R.&R. any prior assurance that I would write a positive review in order to borrow their tool. I wrote all the favorable comments because it really is that great of a tool and their brake line is absolutely wonderful to work with. As mentioned earlier, I purchased the Titan Tool and I did not get paid to cover their tool in this post.

Bottom line—Fix your own rusted brake lines and save

Posted on by Rick Muscoplat


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