I have a 71 with a big block set up that has discs up front and the heavy duty drums out back(the finned drum)the original mastercylinder didnt fit so i installed that dual diaphram one in all the chp mag's now that its in the car stops like crap the pedal feels like there is a brick under it and the car wants to go through stop signs..also it has an electric vacuum pump that pulls about 20 inches...my question what do you think is wrong with it? it isnt the converter its a 3000 stall any clue feel free to suggest problem or sol'n

Sounds like the metering valve is triped. Does your warning light work.

Troy

I HAVE THE SAME PROBLEM....WHAT IS A METERING VALVE WARNING LIGHT. AND WHEN IS IT SUPPOSED TO COME ON. I HAVE ON AND OFF HARD PEDAL AND CAR WONT STOP COMPLETELY SOMETIMES. VERRY SCARY BECAUSE YOU DONT KNOW WHEN ITS GOING TO NOT WANT TO STOP. :eek:

Sounds like the same thing as wild 72 I havent noticed a light. What do you mean triped?

First the obvious, your brakes were bled properly and not leaking, right?

The metering valve compensates for the front disc/rear drum pressure requirements. If it's not working properly then you'll have only front or rear or not enough of either. The brake warning light connects here, if you get this light on your dash then something is wrong. This unit mounts on a bracket on the frame below the booster, follow your brake lines from the master cylinder down and you'll find it.

Sorry I`ve been so long getting back to you.
Last week I shut my boxer puppy (78 lb ) in my shop by mistake,So he spent a night with my 66 elcamino and my 69 ss conv. Glad I had lots of extra clear on them. Been sanding and buffing for 3 days, I think every scratch came out.

Back to your brakes.Cecil has you going in the right direction.The warning light also serves as the emergency brake warning light. Thr metering valve is also a junction block where the front and rear lines branch out, there is a elect. switch in it , and a single wire going to the light.( most are light brown ).

When you have a failuer at the rear, the pressure drop trips the switch,shutting of the rear brakes, and turns the warning light on,but leaves you with front brakes. And visa versa.
The same thing happins if you open the brake system at eather end, while replacing parts or bleeding the system.

To kick the switch back you userley have to drop the pressure at the other end,

There is a special tool that screws in where the switch is and holds the valve open for bleeding purposes. But it is not needed very often.

HTH
GoodLuck
Troy-Curt graemlins/beers.gif

I dont ever remember seeing the light but I have a steerign wheel mounted tach and i cannot see the first 30? mph of my dash so i may not see it because it is being blocked... I know the rear brakes work..Ive locked them up before it is the front brakes that concern me..but from what you are saying you are suggesting that the valve has the front brakes disengaged...right?

If the rear ones are lockig up and the front is not, then I would say the front is not working. See if the switch wire is making connection, check the circut and bulb. When you apply the emg. brake the bulb snould light up.Ground the wire, the bulb should light up.Use a test light on the switch. If it is working,and you push the brake peddle hard it should light if it is triped.Good Luck

Troy

I have the same problem..feels like the brakes are working more in the front..my plug is disconnected to..also have a grinding noise but no signs of grinding

Ok tech guru's I just remembered that because my hooker competition headers are right on top on the little proportionign valve we speak of it is impossible to get to it. What can I do? I think the light comes on with the emergency brake but I'll have to check again.

Originally posted by doggy69:
Ok tech guru's I just remembered that because my hooker competition headers are right on top on the little proportionign valve we speak of it is impossible to get to it. Do you have good brakes until the headers get hot?

Even if i just start the car and Im going down the street and stop at a stop sign within two minutes within racing it around its rough to stop.
Today I was at Englishtown..talked to a brake guy and he suggested that the shaft from the dual cylinder might be lower and thsu giving me a harder pedal and he said even if tis not you could still move it higher to make the pedal more sensative...Is this true or am I chasing my own tail?
Dane