Harmonic Balancer ang tawag dyan.

Ang function nyan ay to absorb minute engine vibration.

The rubber is vulcanized between the outside ring mass and the inner ring which has a key way to locate to the crank. The vulcanized rubber allows the outer ring to counter act the crank vibration.

If you weld the outer ring to the interior mass you will eliminate this function. The result will be a two piece crankshaft(broken in two).

Buy a surplus unit.