zzyzx

You guys ever seen a bleeder screw back out? Happened to me this past week at Laguna Seca. My mechanic bleed the brakes, though it was probably my fault from over torquing the bleeder in the past. He thinks the thread may have been damaged and that caused the screw to work loose.


I was incredibly lucky. On the very last lap of the the last session of the day, I let the car coast down the hill. Had no brakes when I lightly got on them. Barely any pedal even with pumping it. Everything was fine under heaving braking into T11. Went from all fine to zero brake. If I hadn't gotten the chequered flag at that time, I would have had no brakes going into T2. I've been trying to get into the habit of tapping up my brakes, and this will make me now do this more consistently.

alexaqui

I think "regular replacement schedule" is the key to pretty much everything. Yet, I've talked with shops that tell their customers to ignore the Porsche recommendations and just extend everything 4-5x unless you are actively racing...

Why would SS lines be more susceptible to failure than rubber? I'm using high quality SS lines on my E36 and I keep an eye on them regularly. Not sure what to look for to be honest other than bulges/damage to the lines. I'm open to going back to rubber as I'm using stock calipers (with solid guide pins that are an entire issue of failure requiring constant maintenance).

I also had to "patch" a hard line! When I took the hard line out and looked at the bends, I could not get a shop to recreate the line. I also looked at high-quality tube benders and realized that it is not possible to get the same tight 90 degree bends that the factory lines have. I'm now running with a brass connector for the repaired section, connecting the old tube to new. Another point of failure...

This weekend, the top of the bleeder valve broke off (a shop worked on it last). No leaks so we ran it... I had the luck of being the first person to test it on track, so this thread came to mind! Let's just say I went slowly around the first session...

Thundermoose

My buddy drove in to wall at WGI at turn 1 due to loose bleeder screw. It happens. I use a very tiny wrench to tighten these and even then with very little force.

TXE36

There is nothing to see when inspecting a SS line unless it is something quite dramatic. My failed line looked fine, operated fine, until it popped and the brake pedal went to the floor. Even after failing, visual inspection reveals nothing other than brake fluid all over the place.

There are several fail mechanisms for SS lines. A common one is dirt gets inside the line between the teflon core and the braiding. The dirt then cuts its way through the teflon. The teflon core of a SS brake line is actually quite delicate. Then there are issues with fittings and crimps. If you search around you will find more failure modes.

The failure mode of rubber lines seems to be limited to ballooning under pressure, but not rupture. Perhaps the reason is long before a rupture, the spongy pedal from the ballooning makes it apparent that the line is beginning to fail. In other words, the failure mode with rubber lines is less severe and comes with a lot more warning. SS lines can fail suddenly.

The factory BWM rubber hoses (and I strongly suspect Porsche as well) are build quite well with significant reinforcement. They are not easy to cut open and while the outside of the hose looks to be nearly 3/8" in diameter, the inside diameter is very small. I also suspect crimps work much better with rubber hoses because they crush through so much material as opposed to the crimp for a teflon line.

On the Jag with the factory Brembos and SS lines, I was able to use the factory rubber lines from the base floating caliper brakes with the Brembo calipers by using cut down banjo bolts. For the E36, rear calipers are stock, so stock rubber hoses just work. Up front, I have Stoptech fixed calipers and they are not compatible with the factor rubber hoses, so I use Stoptech SS lines up there and replace very two years.

-Mike

jayzbird

zzyzx

Is it actually possible for fluid to weep around a bleeder? I used to think the same thing and seemed to have the same issue, but I've been told that this is not possible and that either I saw fluid that had gone past the piston seals or that there was residual fluid from bleeding. I was also told not to ever over torque these things, and that doing so will just screw up the threads and cause the failure that I had. But maybe someone with better technical knowledge can chime in.

Pretty scary to go from totally normal breaks to no brakes. It wasn't like brake fade or knockback where you can pump up the pedal. When I got back to the pits and inspected the brakes, there was a puddle of brake fluid under one wheel and the bleeder was just a few turns from being out completely.

As I've said, this taught me a lesson to always tap up the brakes on the straight.

jayzbird

mark kibort

Practice match rev downshifts without any brakes to get used to the possibility of brake falure. it can save your car/you. as i mentioned, i survived a brake failure going into turn 2 as well and didnt even get dirty using this technique...... i was feeling something was wrong with the brakes during the lap, so instead of going 125 at the braking point, i was probalby 115, and hit the brakes early, where the line burst. had it been on a 100% approach, the technique would have certainly reduced any chance of wall contact, and still might have been able to keep the car on track. something to think about and practice.