@fozzi58 Not sure if you have tried taking a wire brush to your rotors yet or not and if that helped or if re-bedding your brakes again has solved your issue completely but I figured I would post up the route of repair I chose since we have similar brake and suspension systems installed on our trucks.
After having my mechanic give the brakes and whole front end a thorough inspection to include inspecting the front brake calipers he confirmed that everything with my front-end suspension wise was in great condition (most parts recently replaced). He confirmed that there were no issues with my Wilwood 6-piston TX6R calipers and that the vibration and pulsing in the brakes was coming from the brake rotors themselves.
But I was still experiencing a "looseness" sensation up front and an "after shock" experience in the front-end after going over large bumps and sudden elevation changes in the road; ie sewer lids or grates, changes on the highway between bridge and roadway etc. This was despite confirming there were no issues with my recently replaced OEM front control arms, ball joints, inner/outter tie rods, sway bar mounts and end links.
So I ended up biting the bullet and purchasing new Wilwood rotor rings, front pads, and rotor bolt kits. Even though my front brakes only had maybe 10-12K miles on them. Which sucked but is what it is.
Additionally, after googling around the interwebs I had learned that a few other owners of Silverado/Sierras would talk about expereincing similar front end symptoms as I was and how replacing steering gear or steering mount bushings would resolve it. Another forum member had also informed me of an updated steering gear mount bushing part number specific to our K2XX SUV platform that GM updated and was a potential solution to some experiencing front end symptoms like I was describing. The new updated steering gear bushing is GM Part #84234960 and there are (2). The old bushings are filled with rubber, but leave these open slots on the sides of the bushing that are not filled with rubber. The new steering gear mount bushings GM Part #84234960 are filled with solid hard rubber, not slotted openings on the new ones.
Replacing my old 143K mile steering gear mount bushings with the new updated GM part number bushings has eliminated the play in my front end. No more do I experience or feel "looseness" or any "after shock" going over bumps. My truck rides like new again.
There is one takeaway and minor difference we noticed when replacing the front brakes this time.
First off keep in mind the front 16" Wilwood rotors are a 2-piece rotor design. Each rotor has a rotor ring; This is the slotted or dilled & slotted rotor part that is actually the surface area that the caliper and pad squeezes and makes contact with. The rotor ring is assembled to a Wilwood rotor hat that is basically the hub mounted area of the rotor that mounts to the wheel hub, the rotor ring and rotor hat is assembled with a Wilwood Bolt kit and each rotor is self-assembled with the rotor bolt kit with very specific assembly instructions, torque values, sequence of tightening, along with the use of some lock-tite for the assembly of the 2-piece rotors.
The first Wilwood TX6R Front BBK I had installed for 72K miles with zero brake issues the entire life, and upon rotor and pad replacement probably could have pushed the brake pads another 5-8K miles. The first set of rotor rings and rotor hats assembled with Wilwood Bolt Kit 230-12176 the bolts were torx bit. Disassembling them required the use of a torch and an impact gun turned up pretty high to get the bolts out and disassemble the 2-piece rotors.
The second set of Wilwood 16" 2-piece rotors were assembled the same way and also used Wilwood Bolt Kit 230-12176, however this time the bolts in the kit were hex head bolts and not torx bit. We didn't think anything of it really since the bolt kit was the same part # we figured it was just an "update" or something that didn't matter. As long as the same assembly instructions were followed all should be the same.
So we are now disassembling the second set of front 2-piece rotors, these are the ones that were only 10-12K miles old now pulsing vibrating like crazy under normal use. We did not have to take a torch to the rotor hat bolts (hex head bolts) to disassemble these ones. They unbolted much easier than the first set. Now, it's possible that this was because they were only 10-12K miles old vs. 72K miles on the first ones.
The third set of Wilwood 16" 2-piece rotors the latest Wilwood Bolt Kit 230-12176 showed up and they were with torx bit bolts now again like the originals and not with hex head bolts like on the second set. We have reassembled this third set of rotors and re-used the same rotor hats from my second set of rotors (the ones that were vibrating and pulsing like crazy) and all installed, pads and rotors bedded in, ZERO VIBRATION OR PULSING IN THE BRAKES NOW.
Maybe the rotor hat bolt kit being torx bit vs. hex head bolts makes a difference? Maybe it's just a coincidence? But it was the only variable or change between the 3 sets of brake rotors and the experience with them so far. I have only now had these brakes installed for a few days so they're still very new. I will report back if I experience any issues with them as I put more miles on them.
