Brake proportioning valve

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Saw this term on a listserve about 80 series cruisers. What is this valve? Where is it? The right front brake on my truck sometimes locks up when I have been on it too long, like in line at car pool with the kids. Dealer recently replaced the entire caliper and said it was "broken." Still have the problem occasionally. Assume dealer can't recreate the problem (so don't just tell me to take it back, I wanna know what is wrong). Thanks for any help
 
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[quote author=Macondawg link=board=2;threadid=8896;start=msg76958#msg76958 date=1071692669]
Saw this term on a listserve about 80 series cruisers. What is this valve? Where is it? The right front brake on my truck sometimes locks up when I have been on it too long, like in line at car pool with the kids. Dealer recently replaced the entire caliper and said it was "broken." Still have the problem occasionally. Assume dealer can't recreate the problem (so don't just tell me to take it back, I wanna know what is wrong). Thanks for any help
[/quote]

whatever the real problem is it is NOT the proporting valve, it only effects the rear brakes and even if it did effect the front it would effect both sides equally. FWIW it's located on the frame, driver side up above(and a bit forward) of the rear alxe.

I dunno but when I have had a bad caliper I have always replaced both sides, I would really think a dealer would do the same, at my local dealer they rebuild the calipers in most case instead of replacing.

Not sure what really is the problem. Explain "lock up" a bit more

John H
 
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[quote author=Macondawg link=board=2;threadid=8896;start=msg76958#msg76958 date=1071692669]
...The right front brake on my truck sometimes locks up when I have been on it too long, like in line at car pool with the kids....I wanna know what is wrong...
[/quote]

A bad flexible brake line (the rubber line leading to the caliper) can cause the problem you are reporting.

Rich
 
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[quote author=Rich link=board=2;threadid=8896;start=msg77221#msg77221 date=1071728096]
A bad flexible brake line (the rubber line leading to the caliper) can cause the problem you are reporting.

Rich
[/quote]

Rich - how so?

I'm just curious how the rubber line would cause this, what would be going on ?
 
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[quote author=Riley link=board=2;threadid=8896;start=msg77225#msg77225 date=1071729805]
...I'm just curious how the rubber line would cause this, what would be going on ?


[/quote]

The inner layer of the flexible rubber line can seperate from the outer layer. Brake fluid can get inbetween the layers and force the inner layer to collapse and block off the brake line and in effect act as a one way valve. Thus you can apply the brakes, and the caliper can remain under pressure as the fluid slowly leaks back past the blockage. From the outside, all can look normal.

Rich
 

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Replacing those front rubber lines from the housing to the caliper is a :banana: job unless you don't have experience bleeding...then bump it up another :banana:
 

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