1999 GMC Suburban 1500 4WD brakes pull right

[MrMarty51]

While You had that left side apart, did You take a real good look at that slack adjuster ?
Those things are usually marked with a L for Left and a R for Right.
What You are describing is a classic example that someone has installed a R side slack adjuster into the L or Left side of the rear brakes.
Especially after stating that it was okay, until You drove it for a while then it starts grabbing worse.
At this time, if it were mine wehicle, I would go to the parts store and buy a L, Left side slack adjuster and install it into the left side, adjust the brakes, take it for a drive and then report back.
It is possible that someone in the manufacturing plant may have stuffed a R side adjuster into a L side box.
Buying parts that are improperly boxed is not that uncommon.

 

[dbrannon79]

Something else I thought about too, is when it's starting to heat up and grab jack up that wheel and try to turn it. see if it's harder to turn by hand than the other side. if so, quickly loosen the bleeder screw and see if it releases. I know this is a classic way to diagnose the front for failed rubber hoses, but if this works for the rear, this will tell you there is possibly a blockage in the line between the Tee and the wheel cylinder. usually, a blockage will allow fluid to pass through under the pressure from the pedal being pressed but block it from returning when the pedal is released.

the hose at the Tee wouldn't be the issue in this case because both wheels in the rear would be doing the same thing. the blockage could simply be at the flare nut that attaches to the wheel cylinder. if it was partially frozen on the line when the first person worked on it started wrenching on the line and wasn't watching to see if the line was free on the nut. it might not be fully twisted but enough that it's causing and issue like this.

 

[chestervan]

Hey everyone, thought I'd drop in and give an update. I tried everything - including measuring pressure at each cylinder and it all checked out fine. I've not driven the truck much but it's been annoying that the problem continues. It finally dawned on me that I might have a bent axle flange. Put it on jack stands and sure enough, a really bad wobble. I'm surprised it wasn't perceptible while driving, but it seemed to be almost entirely side to side, not up and down. After a while the spinning slowed as the brakes became hot and sticky. And the oscillations on the offending right rear brakes seemed to cause a corresponding pulse in the pressure on the left side, as they started getting draggy too. Anyway, thanks for all your suggestions and ideas! This is a great forum.