Related Photo Galleries
1. The first step in making sure our ’04 GMC Sierra stopped on a dime was to remove the supplemental brake assist unit on the passenger-side of the booster. This unit is basically an extra vacuum pump designed to kick on if vacuum drops below 6 in/Hg and turns off at 9 in/Hg. Despite its best efforts to supplement the brake booster, a little pump can only do so much when bringing a 4,300-pound truck to a halt.