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Author Topic:   Nodular iron crank???
posted September 18, 2003 11:33 PM
I was checking out a company called Hawk Racing... they sell new "nodular iron" stroker cranks with standard journals for $130 and I am interested since we have a claimer... What the heck is nodular and has anyone got any info on this company??? Thanks..... NYhick

posted September 19, 2003 01:02 AM
To understand what nodular iron is, you have to know what basic steel, and cast iron is:

Steel has disolved carbon in it. Less then 2%. 4140 steel has .4% carbon, 1045 steel has .45% carbon. With low % of carbon steel does not cast well at all, it's like slush. That is why most steel parts are rolled (plate, bar ect), or forged (con rods, cranks ect). Steel has the same tensile strength as compressive strength. Steel also transfers harmonics very well. A steel crank will ring like a bell if you tap on a counterweight with a wrench.

Grey cast iron (engine block) has approx 4% carbon in it. This is about the right percentage of carbon that makes it pour well into molds. With that much carbon, it cannot be disolved with all the iron. The carbon settles out and makes what looks like tiny cracks all throughout the cast iron. All cast iron is pre-cracked. The cast iron has good compressive strength, but poor tensile strength due to all of the tiny cracks in the cast iron. The cracks are imperfections, stress risers where the material pulls apart. However, the tiny carbon flakes absorb harmonics and dampen vibration. Alot of heavy machine bases ect are made from cast iron. It also has poor ductility. Just like concrete.

Nodular iron aka ductile iron. Has a small amount of magnesium added. This makes all the tiny carbon flakes turn into round nodules. This gives the iron alot more ductility and higher tensile strength then plain old grey cast iron. You also have the carbon nodules that help dampen harmonics similar to cast iron. The GM cast cranks are made from nodular iron.

So the nodular iron cranks your talking about would probably be similar to a stock gm crank, material wise.

posted September 19, 2003 07:56 AM
also from what i've been told...anything advertised as "cast steel" is nothing more than nodular iron. just a fancier name.


posted September 19, 2003 12:45 PM
Where can we get more info on this "Hawk Racing" cranks?

At that price it'd make a good claimer piece.

posted September 19, 2003 02:37 PM
I bought one of these (hope link works) for next years motor. I think it's the same crank Hawks sells. I must say it looks pretty much just like the pic in the Ebay listing. When I mic'd it up, there's a few tenths (.0001"'s) taper on the journals. Like maybe .0002"-.0003" on the worst. But, for $155 to my door, I can't complain. That's about as straight a journal as you'll get on a reground stock crank. Yes, the big dollar ($500+) steel cranks are deadnuts on, but I can live with .0002" taper considering I'll be running .0025" clearance (or .0022"-.0025" when all's said and done).

Here's a good description of the strength of crank materials. Basically, an aftermarket nodular iron (or cast steel as some companys call them) crankshaft is as strong as a factory steel crank. It's a ton easier and cheaper to get an aftemarket nodular iron piece compared to ferreting out a stock steel crank that hasn't been beaten to **** already.


posted September 20, 2003 07:49 AM
I bought an aluminum flywheel from hawks racing.Turned out to be a fidanza brand which cost about 400 bucks through them and 279 from hawks.Was a quality piece to.Been rinnig it all year .Everything they sell has somebody elses name on it when you get it.

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