I installed a set of Stoptech Stainless Braided brake lines awhile back, and I noticed last night while painting my calipers that the inside of my new 15" wheel was missing some paint. Strange sight---then I realized something must be rubbing and I looked closer at my brake line and noticed that the grommet mount it was on had come off. I had a zip tie holding it in place because the Stoptech grommet was kind of loose.

Anyways, I noticed that the plastic sleeve outside the braid was worn down to the metal braid. I know this isn't a good sign, and they need replacement, but what exactly does the plastic sleeve do? Will it leak if it's compromised? I didn't see any brake fluid, and brake pressure is still fine. I wrapped the worn parts with electrical tape for now--not like it'll do much, but as a precaution, until I can get it replaced.

 

The plastic layer over the braid is there mostly to protect the braid and underlying high pressure tubing from dirt, moisture and abrasion. It has no effect on the pressure handling of the hose itself. it also helps to spread out the bending forces and prevent kinking. If the braid has been exposed and worn, even slightly, it's best to replace the line, as this has become a weak spot. If the outer plastic layer is slightly damaged without exposing the braid, you'll be okay.

The 'business' part of the brake line is the tubing inside of the braid, coupled with the braid itself. The inner tubing provides the leak-proof fluid path and the overbraid acts as a girdle and give the assembly it's pressure handling capability. Any outer layer is there for protection and to provide a means of clasping the line in brackets and holders.

 

I agree with Greatbear, but based on personal experience if the braid looks like it has made contact with the wheel at all I would replace it.

I had this problem last year, with one SS brake line lightly rubbing on the inner edge of the wheel without my noticing it. I hit the brakes hard one day, and the line ruptured. That really freaked out the brake system, and I'm lucky to have kept the car on the road as it was really squirming around violently. I was left with very little use of the brakes, and actually had to use the parking brake (e-brake) to slow the car and creep to a safe place to park it. Fortunately the stock line was still available so after bumming a ride I did a parking lot repair.

Don't take chances.

Scott
90SM