Brake system fail safe question....

[slocrow]

In another post Lynn (Rumrumm) stated that he lost the brakes on a 92 vehicle. I semi posed a question so let me do it correctly.
Why with a dual master are there reports of complete loss of brakes? You know, pedal to the floor. Shouldn't the dual system provide some brakes? Isn't that the purpose of a dual system. I'm assuming that we are smart enough to know when one end goes and that this occurrence isn't happening only when the second system fails.
Lynn's is the second time I've heard of this complete failure. My brothers mid 90's Jeep was the first and he only blew one line. The front left was a rust out. ........................Frank

[enjenjo]

I have had it happen to me too. In every case there was a defect in the second braking system, that was masked by both systems working. Things like a leaking wheel cylinder, a second line bursting, stuck combo valve, brakes out of adjustment. This has never happened to me when the rear brakes went out, only with the front ones.

[Mikej]

The rear brakes could not be working and you wouldn't notice as the front does most of the stopping. I had front brake line break on a 73 Scamp and still was able to stop. If you would have been able to give it a quick pump, it might have able to stop with the rears. I almost always give my coupe a quick pump just to make sure I have brakes. Paranoid?  The brakes didn't work very well, when I first got it. Took me a couple of years to get it sorted out. Now its habit.

[Mac]

Just last week my son called from his GF house to tell me his brake pedal goes to the floor and he can't drive his Tracker home. I told him to walk around the car, looking underneath for dripping while the GF works the pedal. He came back to report he found the leak on the pass. side 2 ft. in front of the axle.
I figured OK, it's a rusted line to the rears and grabbed a can of brake fluid, a pair of wire cutters and vice grips. The plan was to cut the line ahead where it wasn't so rusted, fold it over, pinch it tight and limp home on front brakes so we could work on it in the shop.
Got the line folded and pinched, the master filled back up but I couldn't get pedal. My son, who's up under the hood watching the level in the MC, hears a hissing noise over by the front pass. side as I'm working the pedal, and we find another line rusted thru just an inch before the RF hose connection. It might have been bad if that front line held for just a couple of the 15 mi. trip home.  
We came back the next morning with car ramps, more tools and put new ready lines in right there in the driveway.

[jaybee]

I only had it happen once.  Think the front cup seal got hard and it just bypassed the fluid instead of sealing either end of the system.  I say "think" because it was -20* that morning and once it warmed up to 5 they worked OK but with a low pedal.  I limped it home and replaced it.

I learned something important about emergency brakes that way.  The car had a pedal-style ebrake with a tiny pedal parked right at the edge of the dashboard.  It worked fine when parked, but when needed it to stop the car it was a really bad design.  I tried 3 times but while the car was rolling toward a busy cross street I just couldn't get my toe on the pedal and get it depressed.  

Pedal ebrakes are fine with me but the lesson is that the position of EVERY control is important.  I prefer a handbrake now.

[58 Yeoman]

My wife says I should quit reading about all your problems here.  We were coming home from Peoria this afternoon, when I hit the brakes to stop for a sign, the brakes went to the floor, on my '99 Ranger. I still had some pedal, so I drove it the 10 or so miles home on the highway.   When I got home, I could see fluid dripping near the left rear tire.  I crawled under it, and sure enough, the long line from the front blew a leak.

I jacked it up, and found a joint under the drivers' seat, but when I put some wrenches to it, the front line fell apart too.  94k miles, but Illinois salt did a job on the underside.  Looks like a fun job in store.