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Discussion Starter #1
I know a cracked flexplate can make a sort of knocking or ticking sound but I have never heard one in person. When the trans gets up above 160 it starts to make a sound like this. Its coming from under the car so I know it isnt the motor and I changed collector gaskets with no change. Ive checked for the converter to flexplate bolts hitting but havent seen any marks on them. Would this be a good guess? What flexplate would you recommend behind a little 350 with a th350 with a 9/12 inch converter with 3000 stall rpm?

Thanks guys
-Dan
 

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If it were the flex plate i would think you would hear it all the time or at a certain rpm. The trans temp shouldnt have any affect on a cracked or broken flex plate.
 

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Discussion Starter #3 (Edited)
If it were the flex plate i would think you would hear it all the time or at a certain rpm. The trans temp shouldnt have any affect on a cracked or broken flex plate.
It always make the sound but very faint. It started one day when I was out testing the converter that stalled at 4400 rpm. I didnt like that and I thought maybe it didnt either. :( But once the trans starts to warm up I can definitely hear it. I thought maybe the expansion as things heat up might be making it worse or causing a bolt to hit harder. But I haven't found anything yet. Im going to try disconnecting the converter and run the motor up to temp just to make sure. Either way, Im going to put in a new one when i change converters just to eliminate the stock rusty flexplate. I also had to drill out the holes to 7/16 for the new converter. Live and learn I guess lol.

-Dan
 

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Pull the dust cover and look at it while rotate the flywheel with a flywheel tool. You may need to remove the bolts. slide the converter back and inspect around the holes for cracks.
 

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sometimes a cracked flexplate will sound like the engine has a bad knock like a rod or main bearing. I could be wrong but if you put it into gear and try to stall it sound would get worse??? anyways just jack up the car check for cracks. Usually it cracks around the flexplate bolt area at the crank.
 

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when ive seen flex plates break, the usually break around the bolts at the crank. u can usually deff hear it on start up, or shut off. but the best way to know is just to pull it off and check it out.
 

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Discussion Starter #7

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My friend had a similar issue. Ended up being a slightly loose dust cover. A washer in between the cover and trans did the trick. Maybe something to check before you pull everything out.

I bought Summits brand SFI flexplate with similar specs to your TCI. Too early to comment since its not in yet but it looks pretty hefty and solid. The welds look good. But that price for the TCI doesn't seem too bad either.
 

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I had one crack between two of the big holes in the middle of the flex plate.
We used a big long screwdriver (2ft) as a stethoscope to find the sound was coming from the bell housing area.
 
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