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