Looking through a Hot Rod magazine the other day I came across this item bolted to the front of the crankshaft called the harmonic balancer.
How does it work, and why is it necessary if we already have the flywheel?
A previous thread on this subject, particularly GaryT’s excellent post.
To some degree, the crankshaft has to be balanced throughout its length. There are separate forces acting on the front compared to the rear, so the flywheel alone can’t handle everything. For more info, Google on harmonic crankshaft balance. Check out some of the sites that come up on the first page. They get into the nitty-gritty of crankshaft balancing.