Harmonic Balancer/Underdrive Pulley

The SLP 100221 Harmonic Balancer/Underdrive Pulley is a performance upgrade for 1998-2002 LS1 F-Body vehicles. This unit provides a 25% underdrive, which can contribute to increased horsepower and improved throttle response. Unlike many aftermarket alternatives, it is constructed entirely from steel, offering greater durability. Key design features of the SLP 100221 include extra-tall belt-retention walls to eliminate belt slippage, a common issue with other LS1 balancers. It also incorporates integral timing marks for accurate engine timing and built-in puller-mounting threads for easier installation and removal. This pulley is keyed for high-RPM and supercharged applications, ensuring reliable performance under demanding conditions. It is designed not to cause false knock retard or erratic power curve dips. Installation of the SLP 100221 requires two new drive belts (Gates #K060763 and #K040378 or equivalent, not included) and the use of GM tool J 41665 for proper installation of the balancer. The product includes a new balancer bolt and detailed installation instructions. This pulley is exclusively for LS1 F-Bodies.