Broken crankshaft, how does this happen?
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
I think there are too many possibilities to be certain of the cause w/o a laboratory evaluation. Couldve been clutch/flywheel balance, engine balance, dampner balance, knock/detonation, crank flaw. But u can see the separation is on the journal/counter weight junction which is a high stress location. That location is where most performance cranks have a generous radius and better yet a "rolled fillet" (cant recall what that is now but chevy used it on the LT4 crank which was a cast crank too). That area has a lot of shear force as the crank tries to twist - a result of a 90 degree crank.
Now a something a flawed crank with do when it fails is sometimes split on a counterweight throw and the engine continues to run slapping the pieces of the counterweight together on each revolution. Your mileage and performance will vary with this.
Those are some nice looking rods and hopefully u will be able to reuse them. I think u need to inspect all your balanced parts before reassembly to prevent recurrence. If that clutch/flywheel is suspect then ditch it.
Now a something a flawed crank with do when it fails is sometimes split on a counterweight throw and the engine continues to run slapping the pieces of the counterweight together on each revolution. Your mileage and performance will vary with this.
Those are some nice looking rods and hopefully u will be able to reuse them. I think u need to inspect all your balanced parts before reassembly to prevent recurrence. If that clutch/flywheel is suspect then ditch it.
