Originally Posted by Frank Reiner

Re: Balancing of MB flywheels, both manual trans & auto trans

In the manufacturing process, all flywheels are neutrally balanced at the end of the machining steps. They are then delivered to engine assembly and build-up. In build-up a flywheel (and front hub) is mated to a crankshaft, and the unit is checked for balance. In many instances, but not all, metal may be removed from any part of the assembly, including the flywheel, to achieve the desired balance condition. As a consequence, many flywheels will be drilled to remove metal such that the flywheel, checked alone, will no longer be neutrally balanced. It is for this reason that Mother Benz specifies that all replacement flywheels be matched for balance/imbalance to the original condition. The shop manuals illustrate the tool that can be used, and the procedure for matching.