Replaced Brake Lines

[Bubbles]

I followed Mr.5's DIY to replace the mid brake lines (here:http://www.e90post.com/forums/showpo...1&postcount=17).
One of the more challenging mods I've worked on to date. My hands paid the price because there isn't much room to work with.

I went with Stoptech Stainless lines. Great quality but I wish the lines had the "star design" at the hose connects that the OEM lines have to prevent rotation as you tighten down the lines. ECS lines have this with their "exact fit" lines. It wasn't a huge issue, but given the challenge in swapping the mid lines, every bit helps. The install for the lines to the calipers are a breeze.

Tip #1: depress the brake pedal about 2 inches using something to wedge between the seat and the pedal to prevent significant fluid loss while you are wrenching away. The fluid loss was minimal during the nearly three hour install (second time around will go quicker).

Tip #2: You need a quality Flare Nut Wrench 11m to loosen and tighten the hard lines. The metal is soft and will round off very easily. I bought 6 identical wrenches from pep boys, out of the six only one had the tolerance I was comfortable with. Also, I hit the bolts with Liquid Wrench (any penetrating oil should work) the day before to ease breaking the nut free. I loosened it to the point I could use my fingers to remove the line.

Did a full flush with Castrol SRF brake fluid using a Motive pressure bleeder. I always pull the old fluid from the reservoir with a measuring syringe as there is no reason to push old fluid through the system (don't pull too much and add air). I then top off the fluid reservoir with fresh fluid and attach the pressure bleeder (I don't add fluid to the pressure bleeder). Start with RR, RL, FR, FL (Facing the rear of the car).

I bled the rear lines first. Starting with the RR line until nearly half the reservoir was depleted, released the pressure AT THE BLEEDER TOP, then refilled the reservoir and bled the RL line. Refilled the reservoir again and bled the FR and FL (Refill was necessary due to the length of the lines).

The Feel: I was skeptical at first, but the feel is great, tremendous actually. Much more brake-by-wire feel. The OEM lines are very good, but the difference in pedal feel is significant. The true test will be at the track, I expect consistent firm pedal feel for longer than can be achieved with stock lines.

Running Stoptech ST-60s with Pagids RS29s on the front and Stock Calipers and RS-7 Pagids on the rears.

[biggynuts01]

Feel any difference?

[mkPOTO]

i did when i ran the same lines, pedal feels stiffer and when you stomp on them there isnt much delay like stock (it might be all in my head lol)

[Bubbles]

Originally Posted by biggynuts01

Feel any difference?

Originally Posted by mkPOTO

i did when i ran the same lines, pedal feels stiffer and when you stomp on them there isnt much delay like stock (it might be all in my head lol)

Well put mkPOTO, the seems to be a reduction in the delay, a much more brake-by-wire feeling.

The pedal feels great.

[e92zero]

^^^mkPOTO/Bubbles, how much of the pedal feel difference do you think is because of the fresh/new/different brake fluid vs the ss brake lines?

[mkPOTO]

Originally Posted by e92zero

^^^mkPOTO/Bubbles, how much of the pedal feel difference do you think is because of the fresh/new/different brake fluid vs the ss brake lines?

less travel for sure, i dont have to stomp on them to stop, now all i have to do is push it lightly. Huge difference from when I went to the track with stock lines, I had to brake early sometimes and now I just push it alittle more brake better on the aftermarket lines

[Bubbles]

Originally Posted by e92zero

^^^mkPOTO/Bubbles, how much of the pedal feel difference do you think is because of the fresh/new/different brake fluid vs the ss brake lines?

When I swapped on the BBK a few weeks ago, the pedal did not feel this linear. Even cold, the feel is different.

I've flushed my brake system before with fresh SRF fluid and this feel is not from new fluid.

[e92zero]

^^^Thanks for the info, mkPOTO/Bubbles.

[Bubbles]

My hands are healing and I must say the upgrade is worth it.

[Sleeper519]

Nice job. Didn't the BBK kit come with SS lines?

I thought it was interesting that you don't fill the pressure bleeder with fluid, just refill the reservoir periodically. Any advantages? I may try this just to keep the bleeder hoses from getting all gooey.

[LiM3y]

Originally Posted by Sleeper519

Nice job. Didn't the BBK kit come with SS lines?

I thought it was interesting that you don't fill the pressure bleeder with fluid, just refill the reservoir periodically. Any advantages? I may try this just to keep the bleeder hoses from getting all gooey.

I have tried both methods and now just refill the reservoir and use the power bleeder to provide pressure. If you use hose clamps (I put a ball valve in the bleeder hose), you can keep the pressure in the bottle while you top off the reservoir in between bleeds.

[THE TECH]

Originally Posted by Sleeper519

Nice job. Didn't the BBK kit come with SS lines?

I thought it was interesting that you don't fill the pressure bleeder with fluid, just refill the reservoir periodically. Any advantages? I may try this just to keep the bleeder hoses from getting all gooey.

+1

[THE TECH]

Also, which Motive bleeder cap are you using? I need to buy the Euro one for mine and they make two different ones.

[Bubbles]

Originally Posted by Sleeper519

Nice job. Didn't the BBK kit come with SS lines?

I thought it was interesting that you don't fill the pressure bleeder with fluid, just refill the reservoir periodically. Any advantages? I may try this just to keep the bleeder hoses from getting all gooey.

I bought my BBK used (front only), so I don't blame the seller for not wanting to deal with the mid-lines. I did swap all brakes to SS lines (including the stock rear calipers) I don't fill the pressure bleeder because I believe if you factor in clean up time, not filling the pressure bleeder saves you time. Plus, I like to keep my risk of brake fluid spillage to a single location and I think it adds to the longevity of the bleeder's hoses.

Originally Posted by LiM3y

I have tried both methods and now just refill the reservoir and use the power bleeder to provide pressure. If you use hose clamps (I put a ball valve in the bleeder hose), you can keep the pressure in the bottle while you top off the reservoir in between bleeds.

Interesting, but I'm conservative and release the pressure completely between fills, again just a cost benefit to me.

Originally Posted by THE TECH

Also, which Motive bleeder cap are you using? I need to buy the Euro one for mine and they make two different ones.

I believe it's the Motive European "Black Label", it's not the one that comes with the bleeder.

[THE TECH]

Originally Posted by Bubbles

I believe it's the Motive European "Black Label", it's not the one that comes with the bleeder.

Thanks.

[adc]

I just replaced my clutch slave cylinder in my Miata, for which I had to buy a set of flare wrenches. I can feel the success of that operation coupled with the new tools pushing me towards doing this mod on the M3. lol.

Thanks Bubbles!

[1SICKM]

How does depressing the brake pedal prevent fluid loss? I would think it creates more because your pressurizing the system

[Bubbles]

Originally Posted by adc

I just replaced my clutch slave cylinder in my Miata, for which I had to buy a set of flare wrenches. I can feel the success of that operation coupled with the new tools pushing me towards doing this mod on the M3. lol.

Thanks Bubbles!

Do it man, you won't regret it!

Originally Posted by 1SICKM

How does depressing the brake pedal prevent fluid loss? I would think it creates more because your pressurizing the system

You'd think but it actually slows the fluid loss, think of it creating a pseudo closed system.

[schnell325]

Good to see a review of the Stoptech SS lines.

[JAJ]

Originally Posted by 1SICKM

How does depressing the brake pedal prevent fluid loss? I would think it creates more because your pressurizing the system

When the brake pedal is fully released, there's a duct that opens between the reservoir and the master cylinder. As the pads wear, fluid flows from the reservoir into the master cyliner to keep the system full.

When the pedal moves forward, the first few millimeters of movement close this duct off. If you close the duct before you open up the brake lines, no fluid can flow into, through and out of the master cylinder. Surface tension combined with the slight vacuum that forms keeps the system from draining while you work on it.

[Bubbles]

Originally Posted by JAJ

When the brake pedal is fully released, there's a duct that opens between the reservoir and the master cylinder. As the pads wear, fluid flows from the reservoir into the master cyliner to keep the system full.

When the pedal moves forward, the first few millimeters of movement close this duct off. If you close the duct before you open up the brake lines, no fluid can flow into, through and out of the master cylinder. Surface tension combined with the slight vacuum that forms keeps the system from draining while you work on it.

Good explanation, thanks.

[THE TECH]

Where's everyone getting their Castrol SRF from? And, are you buying more than one liter for the flush?