Crankshaft turned down
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Crankshaft turned down
Looking at stroker cranks from some of the suppliers I have seen cranks that are brand new but have been turned .010 on either the mains or the rods. They are quite a bit cheaper than non turned. They have been turned by the manufacter I assume there was just some cleaning up needed. These are Eagle 4340 cranks. Turning .010 is not much, what do you guys think on the strength of these cranks. No blower or high hit of nitrous but I was thinking in the future of about 500 HP spinning 6500 to 7000 rpm.
Le Mans Master
Joined: Mar 2004
Posts: 7,465
Likes: 1,486
From: Little Rock AR
There were some factory defective Eagle cranks out there being unloaded on Ebay and other places a while back. Turning a crank does not make it significantly weaker. The quality of the re-work would be the critical factor. Buying one that does not need rework would be my preference.
I have used Eagle SIR rods before and they were realy nice. Out of the box they look impressive. The balancing guy said they were well matched and I had to have him show me where he did any weight removal because it was so small. They are spinning around at over 7000 RPM inside the 302 in my Camaro and I am not afraid of them letting go. I would buy them again.
-Mark.
I have used Eagle SIR rods before and they were realy nice. Out of the box they look impressive. The balancing guy said they were well matched and I had to have him show me where he did any weight removal because it was so small. They are spinning around at over 7000 RPM inside the 302 in my Camaro and I am not afraid of them letting go. I would buy them again.
-Mark.
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
I don't think .010 is all that critical. For me it would come down to pricing. If it were $20, then I would not consider it. However, if the price is reduced 50%, that's a different story.
As to who turned them doesn't really matter. I would be more interested in why it had to be under-sized. It may have only been a machining error and they ground to much off one journal and instead of tossing the whole item decided to regrind and discount.
As to who turned them doesn't really matter. I would be more interested in why it had to be under-sized. It may have only been a machining error and they ground to much off one journal and instead of tossing the whole item decided to regrind and discount.
Burning Brakes
Joined: May 2001
Posts: 1,102
Likes: 0
From: spring city pa
A .010/.010 crank is safe to use as the surface hardness will still be intact . The trouble comes into play when the shaft has been ground taking too much material off the shaft at one time . This will burn the surface and damage the heat treat . There are kits available with a solution that can be applied to the journal surfaces that will indicate if the surfaces have indeed been burnt ! The crank grinder operator simply removes the blue burn marks when doing the finish polish operation . The corner radius of each journal should be very carefully inspected visually by the purchaser for a smooth tool mark free transition .
Good luck
geo
Good luck
geo
