I've been fighting brake issues since I bought this truck in '07, mainly the brake pads aren't fully contacting the rotor surface. When I bought the truck, it was the front inside surfaces that had a band of corrosion (new pads & rotors), and it has happened several times since then on both front and rear, but this is the first time I've noticed it on the outside surface of the rotors. Here's a picture of one of the rear rotors, the other rear rotor looks identical.



The visible side of the front rotors look ok, but I can't see the inner surfaces due to the fixed plates that protect the rotor.

The truck now has a shudder when braking at ~35mph, almost like the rear brakes aren't getting must grip for a good bit of tire rotation, then hit a good patch of rotor, then back to the poor braking section. The ABS light is not activating.  

So far, I've replaced at varying times:
Pads
Rotors
Calipers (Apr '11)
Flexible lines (Apr '11)
Hydraulic brake booster (Aug '13)
Hard lines (July '14)

So pretty much the only things still original to the truck are the ABS module, master cylinder and the brake pedal itself.  I've only drive the truck ~35k miles in the 7 years I've owned it, I mainly use it for camping and Home Depot runs.  Any ideas what is causing this?

Kharn

Winter salt and a lack of use.  Bet the truck sits outside year-round, too.

I live in the rust-belt.  I have a summer-only car that is garaged.  2008 with 56K, brakes are perfect.

It sits outside.

I don't have the ability to pull the brakes at home, I have to go to the shop at my work if I want to change the pads (so going to just take a look is a big production, might as well take a big pile of new parts with me). When I last had the calipers off, I cleaned the pins and bores as best I could and put a layer of brake grease on the pins.

Kharn

Iirc those years GMs are somewhat notorious for rear brake rusting. I have an 02 crew cab 2500HD and the rotors are a lot like yours, only mine sits inside, but rarely gets used.  

Almost seems like at one GM acknowledged this issue? Need to do some Googling. I'm getting too old to remember this stuff

Wish I could help. My plan is a rear brake rebuild and then periodic lubing of the pins, moving parts, whatever.

Good luck!

I finally took my truck in to work to borrow a lift for the brake job, turns out I badly needed rear calipers as one side only had one functional piston and the other side was jacked up as well. Advance drove over a new set, now the truck brakes smoothly and quickly. They claim the parts have a limited lifetime warranty, I forget if this is the second or third set of calipers in 35k miles, so I'm definitely writing down the warranty and receipt number for the next time this happens.

But there was a big problem on my trip: I picked up a rock on the way to the shop and my power steering radiator is leaking. I had to search Ebay to find a matching picture so I could call around to find a replacement since its small size and odd location left everyone scratching their heads as to what it was, turns out not even the dealer had one in stock so I limped home and Amazon'ed a replacement. RockAuto doesn't even stock the part.

Kharn

Pads are binding. It's all in the setup of the pads. The 2500 pads have little half loop ears that contact the stainless sliders. They are stamped....badly in most instances. You need to use a file or dremel to open up those loops alot. Then test fit them in the bracket you may need to grind the end of the pad backer plate to shorten them up as well. You want them so loose that you'll think they will rattle.

The pads I just put on definitely fit better than previous sets as far as fit on the brackets, but I did have to remove one of the squeal clips as it just wouldn't bend into a position to pass the bracket without touching.

Kharn

One pad per side should have one sensor the other should have two and they won't go together the wrong way....I have seen new pads where all 4 had two sensors..yeah I just break them off.

 

This is exactly my experience as well regarding the pad to caliper bracket fit. Removing the bracket and cleaning them up helps also.