Engine Harmonic Balancer-OE Replacement Balancer ATP 102256. MSG for any QA! See our other listings. ATP Automatic Transmission Parts Inc. The purpose of an harmonic balancer is to absorb crankshaft vibrations. Harmonic balancers are typically constructed in three pieces. The first piece is often called a hub. It bolts to directly to the crankshaft. The hub is surrounded by rubber… Read more →