2004 GMC Sierra Brake Upgrades - Whoa, Baby!

After a small parking brake shoe adjustment (for a truer parking brake engagement), the new AP Racing brake rotor was slid into place.

Sam then bolted on the rear AP caliper mounting bracket using the factory 18mm bolts. The bolts were then torqued down to 52 lb-ft.

The aluminum four-piston AP Racing brake caliper was bolted onto the caliper bracket using two 10mm Allen head bolts. Each bolt was torqued down to 35 lb-ft.

Looking the part of a race truck, the new AP Racing rear setup was installed in just minutes. Both front and rear AP calipers were fitted with AP's own track-formulated brake pads. Much more aggressive than a street-only pad, the improved bite will help us modulate the brake pedal for occasional autocross days.

A simple test fit was done with the new BMF wheels and Nitto tires and surprising all of us, there were more than two inches of clearance between the back of the wheel and the caliper.

Up front, the pads had been replaced, but the original rotors were still in place after 144,00 miles. Deep grooves scared the surface and caused a severe vibration in the steering wheel. Combine those problems with the under spec rotor thickness and our brakes were a rolling death trap.

Sam got to work removing the factory calipers using an 18mm socket and with the caliper out of the way, he removed the soft brake hose with a flare nut wrench and pulled the rotor off the hub.

It's hard to argue the night and day difference of the AP Racing 14.25-inch rotor and six-piston caliper compared to the factory front brakes.

Sam then bolted the AP caliper mounting bracket to the spindles (note that this was a test-fitment and we later added the McGaughy's 2-inch drop spindle). The factory 18mm bolts received blue Loctite and were torqued to 130 lb-ft. The new rotor was then slid onto the hub. Not shown, we later purchased and installed new bearing hubs for the McGaughy's spindles because our hubs had a slight grind when spinning them. This was the perfect time to do some necessary maintenance, and besides, it was a bolt-on affair.

With a single lug nut keeping the new AP rotor flush against the hub, the new aluminum six-piston caliper was slid into place and bolted down using the new 12mm allen bolts. Each bolt was torqued to 45 lb-ft. During this step, we found the only problem with the AP kit. The new 12mm Allen bolts were roughly 5mm too long and bottomed out on the spindle, which marred the last few threads. We cut down the bolts and they worked perfectly.

If there was any doubt that our truck was going to stop, this photo should quench that worry. Sports car brakes, for a truck that will soon have sports car power and handling—the ultimate combo. Safety is a must and it doesn't get any better than AP Racing.

We were now ready to install the Goodridge stainless brake hose that came in the AP kit. Being sure to keep the hose away from moving parts, the hose was attached to the upper A-arm using rubber isolated C-clamps.

Once the AP/Stillen team learned of our plans to extensively test the truck, they added AP's rotor temperature paint kit.

Three different colors will quickly fade to white once different brake temperatures are achieved. This will let us know just how hot our brakes are getting under extreme use.

Another cool trick AP has under its sleeve, are these caliper temperature indicators. Applied to both our factory and AP calipers, we'll be able to monitor caliper heat during our testing.

We were now ready to bolt the new BMF Novakane wheels and Nitto NT05 tires onto the Sierra. The BMF wheels measured 20x9 inches and the Nitto NT05 tires were 275/40R20.

After a thorough brake bleeding using AP Racing Super 600 brake fluid, the GMC went out for a test drive. Performing several moderate stops from 35mph, the AP brakes were slowly bed in. After the initial stops, several more were performed from 50 mph, with careful attention not to lock up the brakes. Back at the shop, you can see where the pads were mating to the rotor surface.

Completely filling up the BMF wheels, the AP Racing brakes leave little doubt that this truck means business—both on the street and at the track.