ECS Stainless Steel Brake line upgrade


Oct 18, 2016
2009 E93 335i

Stainless steel brake lines can improve brake pedal feel and is a good upgrade when you're doing other brake upgrades. The upgrade is fairly straight forward, however space is limited and can be difficult if you have large hands.

In this process you'll need to bleed the brakes, so it would be wise to have a brake bleeder, a brake line wrench(11mm on my car), brake fluid and brake cleaner to clean up the spilled fluid. Also make sure you have a cardboard box to protect your garage floor, a drip pan, rags for soaking up brake fluid as it oozes out of the lines while you're loosening them. A stubby 11mm wrench can come in handy for doing the tight turns. You'll also need a heavy weight or a brake pedal prop like a steering wheel lock to keep the brake pedal depressed.

Brake fluid and brake cleaner will ruin your paint so make sure to avoid getting everywhere. DOT 5 brake fluid is silicone based and is not water soluble.

Rear Lines

The rear left wheel is easily the hardest part of this entire install mainly due to space constraints. If you're looking for a reason to get mad and give up, lets start with this wheel. Start by cracking the lug nuts, jack up the car, put on jack stands and then remove the wheel and you'll have something like this:

There are three lines on the left rear which you'll be replacing, two short lines that feed each rear wheel, one of which goes into the caliper on that side. Since the brake master cylinder is on the driver side in the engine bay, they run both hardlines back to this wheel and then one of the lines runs over to the right side:
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Place a cardboard box down on the ground to protect it from spillage as well as a drip pan to catch the fluid that comes out of the lines once they are loosened. When you remove the lines, a bit more tends to come out once its been fully removed and this is where you'll be pouring it:

Now grab a heavy weight or a steering wheel lock and depress the brake pedal. This will prevent additional fluid from dripping out of the lines while you work on them:

Now get under the car and use your 11mm line wrench to remove the nuts on the bottom of the two short brake lines. Once you loosen the nut, use a rag to remove the nut the rest of the way to catch any fluid that seeps out:
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Now go on top and remove the top nuts. Keep in mind when you release the top nut, a bit more fluid tends to pour out so make sure you direct it to the pan:
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This is a comparison of the ECS line (red) and the OEM line (Black):

Now you'll need to install the new lines. The key to this is getting the collars on the fittings to fully slip into the star shaped brackets. if you don't get it fully seated, then the nut won't be able to catch any threads. Because the top is a more restrictive place, I started with the line furthest from the wheel on the top. I found the best way to get the nut started was to just give the suspension a bear hug, one arm on top one on bottom. Make sure your car is not on a jack and is properly supported by jackstands otherwise you could get seriously injured if the car fell on you. Once that was fastened, I did the other top nut and then went to the bottom. A stubby 11mm can come in handy, do not over tighten or strip this nut out. This is a shot of the top nuts, looking downward:

Here is the bottom looking up:

Next, you'll want to remove the brake line that feeds the caliper starting with the 11mm nut and then use a 14mm wrench on the caliper side. This one does drip more and will pour out a good bit of fluid once removed:
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Once removed, install the new stainless steel line, bleed the lines using a brake bleeder and put the wheel back on. Move over to the other side, where you'll only need to replace one longer line:
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Bleed the line, put the wheel back on and now move to the front.


Oct 18, 2016
2009 E93 335i
This guide has been updated to reflect the process for the front lines. The F30 brake conversion was done while creating this guide, so when the lines are reinstalled you'll notice different caliper covers and small differences.

For those interested, that guide can be found in our Documents section in the navigation, you may click here:


Front Lines

This part of the install is very straight forward and most importantly, very easy.

Put the brace/weight back on the brake pedal, crack the lug nuts and put the front end up on jackstands if it isn't already, then remove the front left wheel.

Position your drip pan below the brake line and loosen the lower portion of the line that feeds the caliper. You won't be able to remove it, just loosen it up.

Now remove the top portion of the brake line, use a paper towl to catch any leaking fluid and then be ready to pour the fluid that comes rushing out of the line into the drip pan below:

Remove the two rubber grommets from the metal hanger. They should just slide out of the side with enough force:
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Here is the new and old to compare:

Take the new line, and insert it into the caliper side:

And then the top:

And secure the grommets:

Now release the brake pedal and bleed the line. Repeat the process on the other side.

You're done!
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