The crankshaft is made of cast iron and has integral counterweights (see Figure 2-6). The main bearing and crankpin journals are machined with deep, rolled fillets for added strength. No machining of the crankshaft during service is allowed, since the fillets may be disturbed.
The front of the crankshaft has a shoulder and key for the mounting of a double-row roller chain sprocket to drive the camshaft. Timing of the crankshaft with the camshaft is performed with the crankshaft sprocket mark in a 12 o’clock position and the camshaft sprocket mark in a 6 o ’clock position.
The crankshaft uses the mass of the flexplate and torque converter to smooth its power pulses to the transmission (see Figure 2-7, view A). During engine manufacture, minor dynamic imbalance may be corrected at the rear by either welding weights or drilling holes in the flexplate.
A torsional damper mounted on the front of the crankshaft absorbs the twisting energy from multiple-cylinder power pulses (see Figure 2-7, view B). The damper is an assembly of a hub/inner ring and an outer ring held together by vulcanized rubber. During engine manufacture, dynamic imbalance may be corrected at the front by installing pin weights in one or more of twelve holes in the torsional damper outer ring.
During service, the torsional damper and crankshaft for each particular engine should be kept together to prevent mismatching. If a crankshaft has been broken, the torsional damper should be inspected as a possible cause for the damage.