Brake issues again

[Mild Thunder]

1989 Crew cab Dually with hydroboost. Since i bought this truck, the brakes havent felt right. Replaced master cylinder, rear shoes, hardware, wheel cylinders, and adjusted them so there is a slight drag. Bled system. Also bypassed the load sensing proportioning valve and replaced the rear rubber hose at the rear axle. Not loosing any brake fluid.

Pedal still has felt low, and braking power from the rears is marginal at best. Yesterday i was towing my boat, and felt truck pulling to the left while on the brakes. Thought maybe it was the trailer. Unhooked trailer, and still pulling to the left.

Got out and felt all 4 wheels. Fronts were equally hot, driver side rear was HOT, and you can smell the shoe a bit. Passenger rear was barely warm. Something is going on with these rear brakes. Had to stop in a hurry with the boat in tow, and the front wheels locked but rears didnt. Tried again to lock them up without the trailer hooked up, and still wont lock the rears.

Owned this truck for 6 months now, really like the truck, but the brakes are making me want to sell it.

[VileZambonie]

Go through again and check your brakes. Post pics if you can. Make sure the primary shoe is on the front. No grease or contamination, no leaky wheel cylinders and that they are properly adjusted. If you feel that you have inadequate braking pressure in the rear after you verify everything the problem is most likely the combination valve. Inside the combination valve is a metering valve, proportioning valve and a differential pressure valve. The metering valve delays the application of the front brakes until enough pressure is generated to overcome the spring pressure of the rear brakes return springs. The proportioning valve limits the pressure to the rear brakes (about 600psi) to prevent rear wheel lock up. So if everything check out ok and there is no blockage in the system get a new combination valve.