Going 6 inches on your 1999–2006 GMT800 Sierra or Silverado? Here’s how to do it without destroying your CV axles.
Why 6" Is the Tricky Range:
The GMT800 uses an IFS (Independent Front Suspension) with CV axles. As you lift the front, the CV axle angle increases. Beyond 3.5", the factory CV joints approach their maximum operating angle.
At 6" Lift – What Fails Without Proper Setup:
- CV boots tear prematurely
- CV joints wear rapidly from excessive angle
- Clicking or clunking from CV joints is common
The Fix: Upper Control Arms (UCAs)
At 6" of lift, aftermarket upper control arms are mandatory. UCAs reposition the upper ball joint to reduce the effective axle angle. Brands like Cognito, McGaughy’s, and SuperLift make UCAs for the GMT800.
6" Lift System:
- Front: 3.5" strut spacer + UCAs
- Rear: 4–6" blocks/leaf pack + extended shackles
Shock Requirements:
Factory shocks won’t work at 6". You need extended-travel shocks specifically for a 6" lift application.
Bilstein 5100 Series Front Shock – Set the Bilstein 5100 to position 2 or 3 for a 2–3" lift, or use their specific 4–6" lift shocks for larger applications.
Tire Fitment:
35" tires are the target with a 6" lift. Most 35x12.50R18 or 315/70R18 setups fit with minor trimming.
Driveshaft Considerations:
On 4WD trucks, extended CV axles or longer UCAs may be needed to maintain proper axle shaft length.
What lift setup are you running on your GMT800? Share your setup and tire size!