Fracturing Crankshafts ?


Gruntled

Gruntled

GT Owner
Dec 11, 2005
203
http://www.stangsunleashed.com/index.php?categoryid=18&p2_articleid=94

This article mentions crankshaft problems with the GT500 and seems to point fingers at the balancer. It also mentions the design and weight of the balancer is similar to the GT. Does this mean we may have a future problem? Tell me it ain't so, that we have a stronger crank in the 5.4 than the 4.6.
 
White Petunia said:
http://www.stangsunleashed.com/index.php?categoryid=18&p2_articleid=94

This article mentions crankshaft problems with the GT500 and seems to point fingers at the balancer. It also mentions the design and weight of the balancer is similar to the GT. Does this mean we may have a future problem? Tell me it ain't so, that we have a stronger crank in the 5.4 than the 4.6.
Click to expand...

Hope so, Vince, especially for those who are going the Heffner TT route!
 
The Shelby has a 5.4L - same basics as the GT - hopefully the specially designed damper for the Shelby is the problem..... Just need to know how much the GT's damper weighs. Anybody knows?


From the articel found at:
http://www.stangsunleashed.com/index.php?categoryid=18&p2_articleid=94

"Sources close to the 2007 Shelby GT500 program are alleging that the crankshafts in the 5.4L GT500 engines are fracturing or breaking at the snout (nose) where the engine damper rides. The sources are alleging that the GT500 crankshaft breakage can be attributed to two complimentary issues. According to our reliable sources, Ford designed a crankshaft damper specifically for the GT500, but the damper weighs in at a hefty 26 pounds.

The weight of the GT500's damper, combined with the stress of the SuperCharger pulling on the crankshaft may be placing too much stress on the crankshaft's snout, which is causing the failures. By comparison, the balancer on the SVT Lightning's 5.4L SuperCharged engine weighs less than 1/2 of the GT500s. The GT500's balancer is similar to the Ford GTs, however is totally different from the SVT Lightning. Unlike the GT500, the SVT Lightning uses a stand alone pulley bracket support system, which threads into the damper itself."
 
Maybe somebody will start to make 5.4 cranks with center balancers like the 4.6.
 
When Ford was doing their testing for the GT, they put the car through "300 hour" test. I believe they run the engine at wide open throttle for the 300 hours. There was some trouble with the crank and ford make mods to it to resolve problems. Sorry for not being more specific, maybe somebody else will remember details.

If anybody is worried, go to the TT conversion because there is no more supercharger and the force necessary to run the sc will be removed frome the ballancer and front of the crank.
 
Well, the balancer is a harmonic balancer intended to dampen the unforseen harmonics from adding up in amplitude and having a catostrophoic effect on the crank itself. A test at a static RPM is likely not going to be revealing of a good or bad harmonic balancer. Real world driving at different loads and RPMs would be a good test. I imagine that as of this writing the collective engine hours of all the GTs in the world is probably 100X that of the new Shelby motor so I think we're probably good to go.
 
I wouldn't worry, two completely different crankshafts are released for the Ford GT and the Shelby Mustang.

The Ford GT crankshaft is svc part number 4G7Z-6303-AB. The Shelby Mustang crankshaft is 7R3Z-6303-AA.

As for the Shelby, that's why they call it testing...
 
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