When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Usually, a few quick jabs of the brake pedal, (all bleeders closed) will "reset" the Prop Valve.
If you suspect the P.V. is stuck in the rearward position, sometimes cracking open a front bleeder will shift the piston forward. And vise-versa.
Its spring loaded and does a fair job of getting you home with half your brakes, in the event you lose some fluid.
I have a picture of the internal workings of the Prop Valve and a picture of the tool that locks the little piston in place.
Click on my avatar, look for brake bleeding photo album.
The Prop Valve has an electrical switch on top that activates the brake warning light. The switch can be removed while on the car and the tool can be inserted without loss of fluid.
A note about Proportioning Valves. Earlier model years did not have one. They had a distribution block.
The Prop Valve was under the master at first, then later moved down to the frame.
Not all warning switches are the same. They changed design, so it's imperative you purchase the correct yr. Otherwise, your wire harness will not fit.
The Prop Valve seldom fails. Not really too much to it, Spring, piston, chunk of brass. Some people have had luck rebuilding them.
1969 with manual brakes.
I have been having problems getting my brakes to work properly, ever since I let the front reservoir of the master run dry When replacing the front calipers
I bench bled the master, so that no air bubbles were present, both gravity bled, and pressure bled with a Motive bleeder, until no bubbles. Pedal is very firm, however the car hardly stops. It seems that when I press the brake pedal super hard when trying to stop, it seems like the rear wheels are getting close to locking up. It seems to me that the fronts are hardly working at all. I would think that if the front brakes were working enter, there would be some dip in the front suspension - virtually none.
I thought perhaps the proportioning valve may be at fault, and replaced it with a new one....no change. At no time with the old or new proportioning valve did the brake light come on in the dash - the light comes in when I cycle the ignition key, so is it possibly a bad circuit from the proportioning valve? I have also tried stabbing the brake pedal hard several times with the bleeder closed, in an effort to reset the proportioning valve
...no change.
I have gravity and pressure bled the system many times chasing this issue - no change.
If the proportioning valve was tripped, doesn't it reset if you crack the front and rear bleeders at the same time?
If I had damaged the master by pushing the piston too far when bench bleeding, would i not have a soft or spongy pedal? Like i said before, it is very firm, and does not need pumping up.
The car is definitely not safe to drive this way, and I need some help and suggestions...
I have been having problems getting my brakes to work properly, ever since I let the front reservoir of the master run dry When replacing the front calipers
I bench bled the master, so that no air bubbles were present, both gravity bled, and pressure bled with a Motive bleeder, until no bubbles. Pedal is very firm, however the car hardly stops. It seems that when I press the brake pedal super hard when trying to stop, it seems like the rear wheels are getting close to locking up. It seems to me that the fronts are hardly working at all. I would think that if the front brakes were working enter, there would be some dip in the front suspension - virtually none.
I thought perhaps the proportioning valve may be at fault, and replaced it with a new one....no change. At no time with the old or new proportioning valve did the brake light come on in the dash - the light comes in when I cycle the ignition key, so is it possibly a bad circuit from the proportioning valve? I have also tried stabbing the brake pedal hard several times with the bleeder closed, in an effort to reset the proportioning valve
...no change.
I have gravity and pressure bled the system many times chasing this issue - no change.
If the proportioning valve was tripped, doesn't it reset if you crack the front and rear bleeders at the same time?
If I had damaged the master by pushing the piston too far when bench bleeding, would i not have a soft or spongy pedal? Like i said before, it is very firm, and does not need pumping up.
The car is definitely not safe to drive this way, and I need some help and suggestions...
