Ralph sent the following to sone of his SS racers, I thought I could get some thoughts here..


JP is still having trouble with his converter. It unlocks or chatters while
cruising at highway speeds. This is the same thing that the fist converter
was doing before it grenaded. He also gave me another clue yesterday that
has me thinking. He said there was a hole in the flywheel inpection cover
that looked like something blew out from the inside. Hmmmm. Since the other
converter didn't physically break apart, what coulda caused that hole. None
of the teeth were missing from the flexplate and i assume the tranny shop
woulda spotted any missing bolts. So here's my theory: One of the weights
fell off the flexplate (assuming the LT1 flexplate is externally balanced).
Now the engine is outa balance and the flexplate is vibrating causing the
converter to destroy itself. There is no noticable vibration rev'ing the
engine in neutral, but he has been complaining about a vibration while
cruising the highway. The facts are: something caused that hole in the
inspection cover, the vigilante shouldn't have grenaded behind a stock
engine and it is still not fixed. As you know he reaces a lot and therefore
the engine is routinely spun to 6000+ rpms. It's quite possible one of the
weights took off.

My questions are: is the LT1 externally balanced with weights on the
flexplate? If yes and one is gone, could that cause the converter to self
destruct? Could that also cause the converter to chatter or just unlock for
no apparent reason? Wouldn't the engine vibrate badly? even in neutral?
What other symptoms would there be?? He's going to take it back to the
tranny shop and take a close look at the flexplate ASAP.

Oh also the inspection pan the covers the flexplate has 2-3 holes in it . it looks like it was hit from the inside by a shotgun, and about 6-8 dents that did not go through.. The old converter looked fine, could a weight have come off the flexplate

Tobin, you out there? I know you know this stuff....help.

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Hmmm, Yes the LT1 is externally balanced on the flex plate, neutral balance on the dampner. It is usually just one weight to compensate for the missing flange on the one piece rear main seal. This is the same on the L98. If you lost that weight it would cause a vibration, especially at specific RPM's. It should cause the same vibration at the same RPM's in neutral too though. I don't think the imbalance could cause a chattering. I wonder if the lockup soleniod is actually sending a chattering signal to the converter? Why, I can not say. That could possibly end up grenading the lockup clutches.