Comments on: Why did front brakes on 1994 Ford Taurus not function when rear brakes failed?

By: Scott S

Scott S — Sat, 12 Jun 2010 03:54:14 +0000

Most of the replies you have recieved are either from crackpots or half wits (several know what they are talking about but oversimplified). First off DO NOT DRIVE the carAT ALL untill this is repaired. Adding fluid is not going to work in most cases AND putting the car on the road in this condition CAN RESULT IN CRIMINAL CHARGES called reckless endangerment. The vehicle must be repaired before being driven! Now on to the problem.

Without more information an exact answer can not be given. But the description you have given makes me suspect that one of the brake lines going from the master cylinder to the rear brakes ruptured. This isnt uncommon on an older car as the lines are steel and rust happens. When one of these lines breaks you will lose all pressure to the opening in that line, and no pressure will be applied anywhere else. This is the law of the path of least resistance. There is a valve assembly above the real axel that proportions the pressure to the rear brakes. If the rupture happens between this valve and one of the rear brakes you will still have some braking, but if it happens infront of this valve you will lose all brake power. There was a time that Detroit put the money into the brake system but we all know what happens when something works too well, the manufacturer starts cutting quality until the product is “just good enough”… Too bad the car prices don’t reflect these cutbacks.

By: bartzan41

bartzan41 — Thu, 28 May 2009 01:44:05 +0000

With an ABS system, this would not have happened, as the wheels are all separated hydraulically. with a non-ABS system, the proportioning valve actually has all the lines hooked to it in order to balance front/rear braking. With any major fluid loss, as in a burst hose or line, the proportioning valve is still trying to achieve 60/40 pressure, and as such will allow pressure to go to the rear, which then squirts out of the hose/line, and kills the pressure to the front. However, the emergency brake is always mechanical, for that very circumstance. Seems odd we call it a parking brake nowadays, because folks seem to forget its true purpose. For an EMERGENCY!!!!

By: Scott H

Scott H — Thu, 28 May 2009 01:44:05 +0000

There are a couple of possible issues here. Maybe your front brakes weren't working properly and your rear brakes had been providing all your stopping power? The front/rear brake systems are not totally independent. They share a vacuum booster and master cylinder. There is also a proportioning valve which directs roughly 60% of your braking power to the front brakes and 40% to your rear brakes. A failure in any one of these components can cause the problem you mentioned.

You also have the emergency or parking brake, which applies only the rear brakes, but is a mechanical system totally separate from the hydraulic system. You should have used that to help you stop.

By: jim

jim — Thu, 28 May 2009 01:44:05 +0000

You where probably driving with only your front brakes for a while. You probably ran low on brake fluid when your lines burst on the rear brakes. The rest of the fluid went in to the calipers as your your brakes wore out. Once there was more fluid in the calipers than in the master cylinder, the master cylinder sucked air and you lost your front brakes as well

By: 144289

144289 — Thu, 28 May 2009 01:44:05 +0000

Jim is right.
You were driving with just half the brakes working, and when you went low of fluid there were no brakes left.