2004 Chevy Silverado - Silver Autocross

After poking around in the stock bin file I noticed the red line was set at 6000 rpm and the automatic was set to shift at 5200 on the 1-2 shift and 5000 rpm on the 2-3. Like a kid in a candy store I got greedy and set the shift points to 5900 for both the 1-2 and 2-3 shifts. HP Tuners software quickly uploaded the changes and another test drive was required. The 5.3 happily pulled up to the new 5900 rpm shift point and the reduction in torque management allowed the firm upshifts it should have had from the factory.	I reduced the torque management table by 50%, turned "Abuse Mode" to "Off", and maxed out the "Max Engine Torque vs. RPM vs. Gear" table to 640. Following HP Tuners directions I was quickly able to upload the new value to the factory ECM.A quick drive later I was grinning like an idiot, smokey burnouts are now possible. GM uses torque management to extend drivetrain life so don't expect any sympathy if you burn up your transmission after reducing torque management and then beating the hell out of your vehicle.	HP Tuners VCM Suite allows real time scanning and data logging, a feature they could have easily charged extra for but included in the package. The data can be saved and used as a tuning aid to determine where changes need to be made after dyno or quarter mile runs.
The shifter mounted Tow/Haul button function is easily changed under the "Performance" setting in the transmission section of the HP Tuners software. Changing the Tow/Haul mode to Haul/Ass mode with an aggressive shift profile allows conservative transmission saving shifts for daily driving and tire smoking launches at the press of a button.	The excessive body roll was the last problem I needed to address before the autocross. A phone call to Hotchkis had one of its complete sway bar packages on the way which is offered as an upgrade for the Silverado SS. Hotchkis has quality sway bar packages for just about every GM vehicle made including you 2WD truck guys.The complete Hotchkis front and rear sway bar kit (P/N 2230) was the most time consuming suspension mod at about six hours, but also netted the most significant improvement in handling.	The gloss black powdercoated, 1 7/16, hollow Hotchkis front sway bar dwarfs the factory installed 1.125 bar. A one-inch hollow bar is added to the rear to balance the package.
Hotchkis upgrades the front sway bar bracket with a gusseted welded part and replaces the soft rubber bushing in the bracket end links with polyurethane.	The massive Hotchkis front sway bar bolts in with minimal frustration.A floor jack placed under the front crossmember makes it easy to raise or lower the front slightly to ease installation.	Rear bar installation requires dropping the fuel tank and drilling holes in the frame rail to mount the end link brackets. Moving the fuel tank is not difficult as long as it is not full of fuel. As the hydroformed frame rails are made of pretty tough steel, make sure you find your holes with a transfer punch and start with a small pilot hole before you drill the .400 hole Hotchkis calls for. Use sharp drill bits and plenty of cutting oil, otherwise the drill might grab the frame rail and try to twist out of your hands. Hotchkis gives torque setting for the fasteners, make sure you use them and check for tightness after a few miles of driving.
Spend some time mocking up the rear bar assembly before you locate your holes. Align the brackets such that the assembly won't bind when it is tightened. The sway bar should be as close to parallel with the ground as possible. Hotchkis can help you select rear sway bar end links for your application. The approximate 4-inch drop in the rear required 6-inch end links.	With the rear bar and brackets installed, the end links might contact the brake lines. As there is very little relative movement, and the lines have a rubber shield on them, this should not be a problem but periodic inspections are warranted to ensure this.

With the stance, alignment, and wheel/tire combo nailed, I felt it was time for some road testing. After about four thousand miles of mixed use I was pleased with the look, but not the handling or ride comfort. Highway driving exhibited very unpleasant characteristics in this combo. Where the truck used to have a very soft disconnected feel on the highway it now acted like it had bad shocks, and on uneven highway pavement it would bob up and down so bad that the CD player would start skipping. Body roll was annoying around town and terrible on highway offramps. Under braking and acceleration the truck would pitch excessively forward or aft. In addition to the handling problems, I still had to contend with Chevrolet's torque management, which was killing wide-open throttle performance and upshifts. While the truck looked good at this point, it had the road manners of a dump truck.

AT THE AUTOCROSS
The sway bar installation changed the truck's ride and handling behavior significantly. While potholes would create more cross-car or lateral input, the truck corners extremely flat and consistent, and high-speed stability and resistance to crosswinds are vastly improved. The real test would be at the autocross, after a little convincing the Northern Virginia Corvette Club was willing to let me run the Silverado at one of their sponsored events. The Corvette Club was cautious about letting a truck run as they have seen BMW X5s get up on two wheels. I assured them my truck was different and secretly hoped I was right. On race day I pulled up to the tech line and informed the inspector I "wanted to race the truck", after I convinced him I was serious he teched the truck and sent me on my way. When the time came for my first run an official reminded me that if I got up on two wheels I was done. Not wanting to make an ass of myself I switched on the AWD and eased the truck around the cones for a humble 78.7-second lap.

After I returned to the pits I took a lot of good natured ribbing for not knowing what the vertical pedal on the right was for. I didn't set any records, but I was safe and showed the promoters of the event I respected the opportunity to run a truck. On each subsequent run I picked up the pace, until my final run for a modest 67.3-second lap placed me in the middle of the novice category. The handling in AWD was fairly neutral, with a hint of understeer. I am sure running in 2WD would result in throttle oversteer. By my last lap the doubters were giving me the thumbs up and everyone seemed to enjoy watching the truck.