Changing Brake Lines

Rob · 04-12-2004, 05:49 PM

I am about to replace the brake lines on the M3 with the stainless steel kind. Is there anything special I need to do when I fill the lines with fluid? I am mildly concerned simply b/c it is not just air bubbles from the fitting I am trying to get out, it's the entire volume of the brake line.

I asked the same question at the 'fest - ignore one if you saw the other.

04-13-2004, 12:17 AM

Sometimes the lines can be a bitch to remove. Get a good set of flare nut wrenches to do it with. Other than that it's not much different than a normal brake fluid chance, from a bleeding standpoint

The HACK · 04-13-2004, 01:20 AM

Quote:

Originally Posted by Doug

Sometimes the lines can be a bitch to remove. Get a good set of flare nut wrenches to do it with. Other than that it's not much different than a normal brake fluid chance, from a bleeding standpoint

Flare nut wrench is a MUST. The metal on the end of the OEM fittings are a very soft aluminum and it gets pretty badly chewed up if you're not careful, and they're tightened to like 20 Nms and on such a small, soft fitting it's hard to get them off.

If you're not planning on keeping the OEM lines, I'd suggest using vice grips to get them off the fitting. Use a flare nut wrench or a crows feet to tighten the new stainless lines on. Crows feet will allow you to torque the line to the proper spec, but I've found hand tightening works well...But you don't want to over-tighten it though.

Rob · 04-13-2004, 02:04 PM

I hate admitting ignorance about stuff that seems to be baseline knowledge for the more experienced.

ops:

Why flare nut? Is it just because they get more of the wrench around the fitting? Oh well. You guys just identified a weakness in my tool supply. Off to Sears for new tools.

As long as we are admitting ignorance, HACK, I read the DIY you posted a link to at the 'fest (and yes, I realized I probably could have found it with a search after you posted it), and it looked like you changed a line and bled that line. Is there a reason not to change all of them and then bleed all of them after the fact?

HACK's DIY (in case anyone else is interested) - http://www.studio2321.com/carstuff/ssl_install/

SteveM · 04-13-2004, 02:41 PM

Quote:

Originally Posted by rwg

I hate admitting ignorance about stuff that seems to be baseline knowledge for the more experienced.

ops:

Why flare nut? Is it just because they get more of the wrench around the fitting? Oh well. You guys just identified a weakness in my tool supply. Off to Sears for new tools.

As long as we are admitting ignorance, HACK, I read the DIY you posted a link to at the 'fest (and yes, I realized I probably could have found it with a search after you posted it), and it looked like you changed a line and bled that line. Is there a reason not to change all of them and then bleed all of them after the fact?

HACK's DIY (in case anyone else is interested) - http://www.studio2321.com/carstuff/ssl_install/

Yes, it is to get more wrench surface area around the nut. It might also be a good idea to spray them with penetrating oil beforehand.

The HACK · 04-13-2004, 02:54 PM

Quote:

Originally Posted by rwg

I hate admitting ignorance about stuff that seems to be baseline knowledge for the more experienced.

ops:

Why flare nut? Is it just because they get more of the wrench around the fitting? Oh well. You guys just identified a weakness in my tool supply. Off to Sears for new tools.

As long as we are admitting ignorance, HACK, I read the DIY you posted a link to at the 'fest (and yes, I realized I probably could have found it with a search after you posted it), and it looked like you changed a line and bled that line. Is there a reason not to change all of them and then bleed all of them after the fact?

HACK's DIY (in case anyone else is interested) - http://www.studio2321.com/carstuff/ssl_install/

The brake lines was one of my first project (I did that almost 4 years ago) and at the time I did not have a full assortment of jackstands to keep the entire car off the ground, so I did a corner at a time.

A proper backyard HACK would've put all 4 corner up, change all the lines then bleed the brakes.

FC · 04-13-2004, 04:11 PM

I replaced the brake lines at the same time I did my first brake job on the benz. Try getting out brake lines that had been there for 12+ years! And no, of course, I didn't have the right tools. Still I got it done. I got air in the system because I let the fluid drip forever (like an idiot) and it took hours to bleed it all out.

That really was the most annoying thing. So as long as you don't let the system drip dry you'll be fine.

04-12-2004, 05:49 PM	#1
Rob The user formerly known as rwg Join Date: Oct 2003 Carmudgeonly Ride: Z4 Location: Vegas baby! Posts: 8,261	Changing Brake Lines I am about to replace the brake lines on the M3 with the stainless steel kind. Is there anything special I need to do when I fill the lines with fluid? I am mildly concerned simply b/c it is not just air bubbles from the fitting I am trying to get out, it's the entire volume of the brake line. I asked the same question at the 'fest - ignore one if you saw the other.

04-13-2004, 12:17 AM	#2
Doug Guest Posts: n/a	Sometimes the lines can be a bitch to remove. Get a good set of flare nut wrenches to do it with. Other than that it's not much different than a normal brake fluid chance, from a bleeding standpoint

04-13-2004, 02:04 PM	#4
Rob The user formerly known as rwg Join Date: Oct 2003 Carmudgeonly Ride: Z4 Location: Vegas baby! Posts: 8,261	I hate admitting ignorance about stuff that seems to be baseline knowledge for the more experienced. ops: Why flare nut? Is it just because they get more of the wrench around the fitting? Oh well. You guys just identified a weakness in my tool supply. Off to Sears for new tools. As long as we are admitting ignorance, HACK, I read the DIY you posted a link to at the 'fest (and yes, I realized I probably could have found it with a search after you posted it), and it looked like you changed a line and bled that line. Is there a reason not to change all of them and then bleed all of them after the fact? HACK's DIY (in case anyone else is interested) - http://www.studio2321.com/carstuff/ssl_install/

04-13-2004, 04:11 PM	#7
FC Solving problems Join Date: Oct 2003 Carmudgeonly Ride: M5 / 718 GTS / Cooper S / GTI / LR4 Location: Metro Boston Posts: 25,257	I replaced the brake lines at the same time I did my first brake job on the benz. Try getting out brake lines that had been there for 12+ years! And no, of course, I didn't have the right tools. Still I got it done. I got air in the system because I let the fluid drip forever (like an idiot) and it took hours to bleed it all out. That really was the most annoying thing. So as long as you don't let the system drip dry you'll be fine.