Brake question

patman

patman

Club Member
I need to replace my master cylinder and proportioning valve on my '71 monte.

First, where can I find the proportioning valve? I can't find it any of the local parts stores.

Second, I've seen that people often use the newer plastic style master cylinder in older cars. Is there an advantage to that? And if so, how do I find out what year and model should I get?
 
Why do you need to replace the propostioning valve ? They rarely go bad ? I could look around for you but the only option may be to send the prop valve in for a rebuild. As for the master cylinder try a local Napa they tend to wharehouse older parts for those cars. Next day service worst case.
 
Sean said:
Why do you need to replace the propostioning valve ? They rarely go bad ? I could look around for you but the only option may be to send the prop valve in for a rebuild. As for the master cylinder try a local Napa they tend to wharehouse older parts for those cars. Next day service worst case.
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I'm thinking the proportioning valve because, I replaced the master cylinder last spring and the pedal was still VERY hard to push. The master cylinder started leaking between it and the booster over the winter. I just replaced the master cylinder today. I tried to bleed the brakes and can't get any fluid to bleed out at any of the bleeders. Pedal goes to the floor and I can't get it to come up at all. I didn't bench bleed the M/C, but I never had before either. Just bleed the shit out of the brakes. I'm going to crack the lines at the M/C in the morning and see if I've got anything coming out there. I've rebuilt/reworked tons of brake systems in the past and you're right, proportioning valves don't usually go bad, but I don't know what else it could be at this point.
 
Hmmm My thoughts are booster problems with the hard pedal and definately you need to bench bleed that master cylinder. The cheaters method to bleed the master is to loosen the line at the MC about 1/2 turn and pump the snot out of it.
 
Sean said:
Hmmm My thoughts are booster problems with the hard pedal and definately you need to bench bleed that master cylinder. The cheaters method to bleed the master is to loosen the line at the MC about 1/2 turn and pump the snot out of it.
Click to expand...

I pulled it off and bench bleed it this morning. Now I have to wait for someone to get home to bleed the brakes. We'll see...
 
So I replaced the front calipers and bleed almost a whole large bottle of fluid through the system. I've got some brake pedal, but it's real spongy. I talked to the guys at inline tube ( the link that you guys gave me ). They told me after I explained my problem, lack of pressure at the bleeders and I can't get the brake warning light to go off. They told me it sounded like the plunger in the proportioning valve in not seated and told me how to get it reseated. They said to crack both fronts at the same time and push the pedal. repeat until the light goes out and then do the same thing to the rears. This should recenter the plunger. So I'm going to try that. Wish me luck....ugh.
 
So, it actually worked! warning light's off and I've got pedal. At least I had it narrowed down to the right component.:cheers:
 
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