Brake line failure

[Marlin]

Well I'll be. I had no idea a proportioning valve could do that. I just thought it regulated the amount of pressure going fore and aft, not that it would allow the front or rear to work if the other went out. Maybe I'll have to disconnect some of my brake lines to see if mine works or not. Since I don't have an idiot light for my brakes showing on my dash I guess it is working.

I suppose the line could have had a flaw in it to begin with, but I can't imagine the amount of pressure that would be required to blow out the inner rubber lining AND the braided stainless. Impressive.

I think my proportioning valve may be bad, or I have a huge clog somewhere between the front and rear, or I suppose it could be in the ABS garbage somewhere.
I may put a bolt in the front proportioning line tomorrow and see if I magically get rear brakes, if not, I will get the valve off the junk VX here in town. Probably a good time for me to remove all the ABS junk and hardline from the proportioning valve to the calipers.

[rowhard]

it's that master cylinder that does the split. This is from 'How Stuff Works' web page:

To increase safety, most modern car brake systems are broken into two circuits, with two wheels on each circuit. If a fluid leak occurs in one circuit, only two of the wheels will lose their brakes and your car will still be able to stop when you press the brake pedal. The master cylinder supplies pressure to both circuits of the car. It is a remarkable device that uses two pistons in the same cylinder in a way that makes the cylinder relatively failsafe. The combination valve warns the driver if there is a problem with the brake system, and also does a few more things to make your car safer to drive.

Sounds like you might have a few problems Chris

[Triathlete]

If you had a "clog" that should of showed itself when you bled the new lines.

[Marlin]

Not if the clog is not 100%, which would explain why the rotors stay clean, I need to pull the pads and check wear. They only have 10K miles on em.
As for the proportioning valve only being a warning, its straight out of the VX shop manual that it has a bypass to separate front and rear. I will figure it out tomorrow when I block the front port.

[Marlin]

Apex sales rep called yesterday, sending two new front hoses, should be overnighted on Monday, Tuesday at the latest. That means no VX for the next 4 or 5 days That means the rear diff rebuild can't happen until the VX is back up and running. Too bad I didn't save the crappy rubber hoses.