I rebuilt the braking system on my suburban because of the following problem. On wet roads if you hit the brakes hard only the right front wheel would lock, none of the others would. I had it to two repair shops, & was told that I could have a bad caliper, bad hoses, bad wheel cylinder, etc, etc. So I went & replaced everything, New master cylinder, new calipers, new drums, new shoes, new pads, new hoses, new wheel cylinders, new springs for the drums, had the brake lines flushed.
I still have the problem with on wet roads the right front will lock up but not the rear or the left front. Now on dry pavement I don't have to worry cause I will stop. My pedal is kinda soft, but not mushy. If you are on gravel & you smack the brakes on you can see where the front are locking up but not the rear.
My mechanic has adjusted out the rear brakes till he could barely get the drums back on, but still the rear will not lock up.
My mechanic said the only thing he could think of is that the brake proportioning valve has gone bad.
My only problem is trying to find one, no parts house carry's it - the dealer does but it cost's $116.00, & they have to order it. Gmparts4less carrys a pressure metering valve. They say that it will fit, but I do not know if it is what I need.
Can you help me out & tell me if this is my problem?
I am @ a loss as with as many cars that I have worked on in my many years, never have I ever run accross a brake problem like this.