My back brake calipers have quit working and I'm not exactly sure why! My car is an '86 and I've heard that the stock calipers are ****ty and that just happens! I've also been told that it could be the proportioning valve and I don't want to spend the money on the brake calipers if it's just the proportioning valve! WHERE is this proportioning valve located on our cars.... I've heard behind the master cylinder and I've heard on the engine cross member! How can I tell what my problem is?? Any help would be greatly appreciated!

 

The proportioning valve is the aluminum block that the brake lines run into after they leave the master cylinder. The two smaller lines exiting the valve run to the front brakes. The larger one runs to the rear.

Proportioning valves don't go bad. There are no moving parts within. The disk brake rear is a complete piece of absolute and total #*@&^!ing garbage!. Once there's a problem you can chase it forever. Buy an adjustable proportioning valve from summit and install a drum rear. The parts are 1/2 price.

 

Sounds like the master cylinder and booster went bad if you're not getting any braking. Have them replaced for $300 or do it yourself for at least half maybe less. The proportioning valve can go bad because it has needles and springs in it, but that would not be causing your problem.

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If the master cylinder and booster were bad then the front brakes wouldn't be working either! The front brakes work perfectly and as a matter of fact I still drive my car on a regular basis with only front brakes! No problems there! That is why I was thinking the proportioning valve might be bad... it's posibble for the needles and springs to go bad in a proportioning valve and not allow the proper amount of fluid back to the back brakes and cause them to quit working!

 

The 88 and older rear brakes have a gm recall, becausee of the adjusters frezeing up, because of a weak spring I beleive, I bet if you adjusted your e brake and losssened the lever up where the e-brake cable connects to the caliper your brakes will work again. Bleed your brakes to fresh fluid helps the adjusts stay free longer.

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You said calipers right? I dodn't recall any adjustors or springs in calipers. By the way I just replaced a proportioning valve for $100 and it didn't fix anyhing. Calipers for the front are $12 after core charge. I don't know how much the rears are, but can't be too far off. Check the soft line, because I know because they cause a lot of problems up front. To answer your question, that is exactly what the proportioning valve is supposed to do when you lose pressure to the rear(like when a line breaks), it only allows pressure to the front. The valves on these also work corner to corner if only one wheel fails.

[This message has been edited by ATOMonkey (edited July 23, 2001).]