It's pretty obvious nobody who has spoken up yet has ever experienced a failure of a dual-chamber system. The scenario goes something like this- - - - - -you'll have a normal pedal on initial brake application, then there's a "pop" that's felt, rather than heard, and the pedal will drop almost all the way to the floor before it gets somewhat firm again. Depending on whether the front or rear system has failed, you'll either experience a nosedive or a long, gradual stop, possibly with some rear wheel lockup and sliding. Any part in the system can fail, a wheel cylinder, a flex line, or even a rusty metal line. Once one system fails, the pedal drop is caused because the two pistons in the master cylinder must physically come together to move the remaining fluid, instead of having a hydraulic push against the second M/C piston. The vehicle will stop, but there will be a noticebale loss of braking effect. A single-line system will lose all the brake effect with a failure anywhere, however!
Jerry
