Crankshaft Failure

[hivewax]

http://en.wikipedia.org/wiki/Crankshaft

what can i look for to what of caused crankshaft failure?



maybe from engine balance... while ago, the distributor gear teeth was chipped. it was replaced with a billet steel. the old gear was a softer alloy. can bad engine harmonics cause this?

a machine shop stroked the original 289 to 347 using a Eagle stroke kit. after the rebuild, the car has seen ~9000 miles. the engine is still under warranty, but they want me to pay for a new forged Eagle crank and labor because from what they said the part failed due to driver's abuse or an manufacturer defect and not from their engine assembly process.

here's more discussion...
http://forums.vintage-mustang.com/sh...p?tid/1508530/

[Pro Stock]

Usually balance and harmonic issues won't cause the damage that you described, was the engine internally or externally balanced ? ask your engine builder this question and then based on his answer make sure that you have used the correct flywheel-balancer combination. As for your distributor gear problem it was probably caused by using a gear that was not compatable with the cam material (cast, billet ect) You can us a stock type gear with a cast iron cam but you need to use a different material gear (bronze ect.) on a billet cam. If incompatable materials where used then that would be the responsibility of the engine builder, there wouldn't have been anything that you could have done to avoid this problem, as far as the balance goes it would only be his fault if he either supplied you with the wrong flywheel-balancer combination or gave you the wrong advice on which combo to use. He's probably smart and will figure a way to cover his butt but give it a try anyway
P.S. we have been running a 347 developement engine on the dyno, 414HP so far
-Dale

[Pro Stock]

Sorry that I failed to cover the crankshaft problem, I was so focused on the cam that I had a brain fart. An out of balance conditition can cause crankshaft breakage and destroy bearings, please refer to my previous post regarding out of balance causes.

-Dale

[hivewax]

thanks for the response. i have the Comp Cams THUMPR cam, which is billet steel. the distributor gear now is steel. the one before was bronze, which chipped. shop said Comp Cams recommended steel gear. the engine is internally balanced... original 157-tooth 18lb. steel flywheel and Professional Products 6.4" balancer.

[MonzaRacer]

Buy a ATI Superdamper, I have as many issueswith Pro Products balancers as I have Fluiddamper. Both of those suck. ATI dampers have never gave me issues, every time I use a Fluidamper I see big issues upon teardown. Anjdfitting them just paline sucks. Heck I even like the Rattler dampers over FD.
sorry I just havent ahd any good luck withthem.
Lee Abel
AFTERMARKET PERFORMANCE