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Discussion Starter #1
Well, we put a new flexplate in the Camaro tonight, and no more shaking. Here's the weird part. After driving it a bit, my buddies rolled into first pretty good, and heard a small thump. After getting it back on the lift, he found out that ONE of the converter to flex plate bolts had sheared off. Any idea how that happens? The only thing I can think of is that he torqued that one down too much. Any ideas??
 

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What kinda bolt? If it's a grade 8 or better, I doubt he torqued it enough to shear it. If it's not at least a grade 8, or it came out of a Mr Gasket package, then it's probly a defective bolt.
 

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Discussion Starter #4
Its a stock lt1 flexplate bolt. It has been off the car and re tightened about 5 times in the last year.... the flex plate was weightedand made the car vibrate like crazy until today. I had the weight taken off and the flexplate balanced within .9g today. It no longer vibrates, but the center hub where it bolts to the crank was slightly bent. It flattened back out when we bolted it up though, so that shouldn't be a problem.
 

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Its a stock lt1 flexplate bolt. It has been off the car and re tightened about 5 times in the last year.... the flex plate was weightedand made the car vibrate like crazy until today. I had the weight taken off and the flexplate balanced within .9g today. It no longer vibrates, but the center hub where it bolts to the crank was slightly bent. It flattened back out when we bolted it up though, so that shouldn't be a problem.
Upgrade the bolts
 

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Discussion Starter #12
Nope, its not bottoming out at all. Looking at the bolt this morning, it looks like it just snapped. The threads were not screwed up at all, nor was the hole in the flexplate, so it appears to be a fatigue failure. We replaced bolts with grade 8 stuff this morning, and all appears well. I got on it a few times pretty good, and it didnt skip a beat.

Just an FYI for all of you out there. This all started because I swapped the flexplate out with a TCI SFI approved unit. The part number was 399174, which is for a 1 pc RMS LT-1 thats been internally balanced. When I got the part, it had a weight on it like the factory flex plate, but the part number laser etched into the part and the number on the box matched what summit, jegs and TCI themselves said it was supposed to be, so we put it on. Well, apparently that weight was not supposed to be there (remember, I'm new to automatics, and VERY new to SBC motors. I've only dealt with 4cyl turbo stuff in the past). I called up TCI to find out what the hell was up with this part, and they told me that there was a batch of the 399173 plates (with the weight welded on) that were mis-marked as the 399174. The 399174 is supposed to be neutral balanced, which is what I needed.

Anyways, the stock flexplate with the weight removed was balanced within .9g, and now that its in the car feels completely different. Thanks for the advice here.


Off to Byron!
 
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