Thread: will a reground stock crank work

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The $200 cranks are probably typical porous Chinese castings. I would feel more confident with an older American ground crank. I personally have a cast iron crank turned .020 under in my truck and it is holding up just fine to over 400 ftlbs of torque. It only costs about $90 to have a crank turned. The crank grinders radiused the jornals and chamfered the oil holes as well.

Originally Posted by 76GMC1500

The $200 cranks are probably typical porous Chinese castings. I would feel more confident with an older American ground crank. I personally have a cast iron crank turned .020 under in my truck and it is holding up just fine to over 400 ftlbs of torque. It only costs about $90 to have a crank turned. The crank grinders radiused the jornals and chamfered the oil holes as well.

Guess what??
Scat,Eagle,etc. are all made in China.
If you are buying a crank under $800 other than a factory steel it's made in China.
Also don't worry to much about we have a crank made in China in a 700+hp dirt burner.
Night after night at 7,500+ rpm's.
Yes,it is made from4340 steel.
Our back -up truck that pulls the race car around has a 496 BBC and it has a cast steel crank in it.
30k miles later and still working great.

Erik is right. And I wonder how many bicycle part fillers are in any 4340 purchased from China.

I require material certs on all critical machinery components at work; why settle for less on our own stuff? No need to answer, but the point is you would be amazed at what variations in quality you can get in materials. 4340 is definitely on that list as well.

What you want to know in general is;

1) Composition ranges and tolerances
2) Processing methods and temperatures
3) Inspection procedure for detecting flaw size and tolerances
4) Stress strain curve (tensile test) on material drop

That's part of why real racing cranks cost real $ ................

Kitz

Originally Posted by kitz

Erik is right. And I wonder how many bicycle part fillers are in any 4340 purchased from China.

I require material certs on all critical machinery components at work; why settle for less on our own stuff? No need to answer, but the point is you would be amazed at what variations in quality you can get in materials. 4340 is definitely on that list as well.

What you want to know in general is;

1) Composition ranges and tolerances
2) Processing methods and temperatures
3) Inspection procedure for detecting flaw size and tolerances
4) Stress strain curve (tensile test) on material drop

That's part of why real racing cranks cost real $ ................

Kitz

As we all know steel is a blend or mix of different metals.
If I remember right both the Scat and Eagle are made in China but machined here in the US.
I have seen a 540 BBC with a Scat crank go over 1,000 on the dyno with two stages of n20.