How to Identify Cast or Forged-Steel Crankshafts

Print this articleCast crankshafts are typically used in low-horsepower applications. They are the least expensive to produce and wind up in all but high-performance vehicles. Steel crankshafts are capable of handling a lot more twisting force and higher rpm than a cast crankshaft. A cast-iron crankshaft is made in a mold, after which it is installed in a lathe and ground to specifications. A steel crank is forged and twisted and hammered into shape.

Related Searches:Difficulty:Moderately EasyInstructions 1

Look at the counterweights on the crank. A large parting line with grinding marks on it is indicative of a forged steel crank. That is because it was forged and bent into shape. The cast iron crank will always have a very thin straight line on the counterweights. This shows where the crankshaft was separated from the mold. The thin line is the parting line between mold halves.

2

Read the casting numbers and call the dealer for confirmation. Look for an engine with four-bolt main bearings and you will very likely have found a forged steel crank. Most all four-bolt-main engines were performance engines that included a forged steel crank.

3

Look closely at the surface of the crank. A forged crank has a relatively smooth surface, while a cast-iron crank has a pock-marked appearance and a rough surface.

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