I had a front brake line blow out on my car yesterday. Luckily I was working on my brake bias in a strait line, and not barreling into a turn. You could actually hear the pop followed by the pedal hitting the floor. NOT GOOD!

Here's why it happed. I had done some welding a few weeks before about 6 inches away from the line. Some weld splatter had hit the line, but nothing that couldn't be brushed off. Braided line is actually "plastic" or teflon under the braided cover. The splatter melted the line and left no visible damage to the outside of the braided line. Plastic just turns hard and brittle when it gets hot, so the failure didn't happed till I put a lot of pressure on the line. Good thing I didn't need the brakes in an emergency situation.

It's easy to ASSume that braided steel line is tuff stuff and stronger than factory stuff, and it is as a brake line. It's actually much more susceptible to outside damage than a factory line. A factory line has several layers that can be damaged without significantly reducing its strength. What you see is what you get with braided line. I hate to admit this but we had a very similar failure on our SAE mini baja buggy at school. We used the plastic/teflon line that’s popular with the dirt track crowd. This stuff is the same thing as braided line without the braid. We had a soldering iron dropped on the line and caused some barely visible damage. The line busted when we got on the brakes hard. Should have realized that braided line was the same stuff with a metal cover.

Conclusion:
If you have braided line, and you have welded around it, or have any visible abrasion damage, change them now. Don’t wait, your life could be in danger.

The second part of this situation is that I had very little to no brakes when my fronts let loose. My theory on this is that factory drum master cylinder didn’t have enough volume to get the rear brakes to engage with the reduced travel the rear piston gets when the front brakes loose pressure. Normally your master is setup like this

Rear fluid ----rear piston----front fluid---front piston--Pedal


When you push on the pedal the front piston pushes on the front brake fluid that pushes on the rear piston and so on. If you remove the front fluid you waste that much pedal travel pushing air, then my rear piston didn’t have enough volume to properly engage my rear disk with the available pedal travel. I have too much rear pressure, so I have to run my wilwood prop valve about 75% closed , so I think I’m going to change my master to one with a larger rear piston to prevent this in the future.

Ohh yeah, I have LS1 brakes on the front and the equivalent to the old 10.5" rear disk that come on the early f-bodies on the back.

 

That sucks but at least nobody got hurt. Our FSAE team has never had an issue with them but you're right, they can be damaged by heat.
On our car, before competition and everywhere we zip tied the line to a hart part we used wire loom and/or slit rubber vac/fuel line for protection. It works out really well and is VERY cheap. It also keeps the lines looking clean and pretty (another reason we did that because our team was getting into the design semi-final's often).

 

yeah, abrasion can be just as dangerous. There is a post over on corner-carvers.com where a guy tied up his brake lines without putting something over the line. He ended up getting chumy with some trees and banged his car up pretty good.

I got some earls lines this time, and the ironic thing is that they even warn about abrasion damage right on the back.