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Discussion in 'Drivetrain, Exhaust and Electrical' started by captdistraction, Dec 13, 2016.
Do you recall who you spoke to?
It looks like a factory damper to me with the dry sump pully bolted to the front. It definitely isn't an ATI.
Black Boss has a Roush built 5.2 in his new car. He does not have a dry sump. Maybe he will chime in with what balancer Roush used.
The Roush built 5.0 dry sump motor in my car has an ATI damper. So far so good.
I should have said that I really don't think there is a problem with the ATI damper. The 5.0L Roush engines I have seen all had a ATI. I suspect that improper installation and / or the damper or damper bolt coming loose would eventually cause a failure.
I’m sure I wasn’t capable of installing it correctly, which explains the failure. Doesn’t explain why I wasted everyone’s time with failure analysis.
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I sincerely apologize, that was not meant as a shot at you.I really was just stating that if something like that comes loose, it can eventually result in a failure due to unseen fatigue.
For example, I found that one of my Howe ball joints had come loose early this summer. I tightened it back up. It sheared in two in turn one at Watkins Glen over Labor Day. I personally believe that the ball joint failure was directly attributed to it loosing torque earlier in the year.
I still think that capts motor was not balanced as good as it could be, which was no fault of his. These are production built motors, even the crate motors. They get what is commonly referred to as a "Detroit Balance". Which is not a balance at all. Its just that all parts are made to a certain weight. Some combinations of parts are good, some are not as good.
Engine balancing is harder than most guys think. My buddy from high school now owns his own engine machine shop. He's scrapped plenty of cranks because they were not able to be balanced to racing tolerances. And not just stock cranks. He's had to send back brand new aftermarket cranks.
On top of this, I sent pics of the crank failure to the head metallurgist at my work. He said it failed due to low cycle torsional fatigue. Which agrees with the theory of a poor balance.
Stock rubber dampers really only work well at one rpm. Fluid dampers work less well at that same rpm but also add damping over a wider rpm range. If the crank has a known torsional vibration issue at a given rpm, lets say 7000 rpm, and Ford designs the stock damper for 7000 rpm, than you will not improve on that with a fluid damper. If you change to non-stock rods and pistons and wrist pins and actually spin balance the crank for these new weights, then maybe the peak torsional is no longer at the same 7000 rpm that it was stock. In that case, its possible that the fluid damper will work better than than the stock one. But without actually testing torsional resonances, we are all just guessing.