A "balancer" is in most cases for torsional harmonics. On a V8 the crank throws are 90° apart, and the constant power pulses and resistance during the compression stroke make the crank flex and produce bad harmonics. The harmonic dampener is designed to absorb them and minimize the damaging frequencies to the crank. I won't use fluid dampeners of any type. I tried the originals and they leaked quickly when abused. I can't imagine any of the imported stuff is any better. The TCI rattler uses small balls to dampen the harmonics. Most dampeners are elastomer, or bonded rubber. The outer ring moves and can "float" to allow the harmonics to be dampened. Fluid dampeners use a viscousfluid and an inner ring that does the same thing. IMO, best ones are ATI Superdampners but they dont always line up well with stock accessory pulleys. Teh SFI ones of various designs are held to a higer standard and generally hold up better. From now on it' all SFI balancers for my engines. I lost a Profssional Products replacement on one engine, and recently a Pro/Street (Cyco products) came apart costing my several hundred in time and parts to fix. So no cheap crap ever again.
