Cracked C6 flexplate

I bought a 1979 460 and C6 this weekend for the Torino project. It had a cracked flexplate. When I unbolted it from the crank, and went to remove it, it broke apart where it was cracked. I have read that it is not unusual for flexplates to sometimes crack near where it bolts to the crank, but was wondering if there is any theory on What causes a flexplate to crack? Should I be concerned of any other underlying issue or was it just the weakest part that finally bit the dust? If I decide to drop in the used motor/trans setup and replace the flexplate with a new one, should I have any concerns related to the reason it originally failed?

I think you should be fine with replacing with a new one I have had on a couple on different engines broken flex plates and looked like they where from starter being mislined and not ingageing right the flex plate doesn't give as much at the bolt area and makes the flex plate brake around the bolts from what I have found.

It seems I've seen more aftermarket plates crack than stock for some reason.

I have had two(2) flexplates crack exactly like yours on my RV. I recently discovered a broken rear transmission mount. I wonder if that might have been the cause.

Look into hays they have a really nice heavy duty flexplate and it doesn't break the bank either .Doug

Aftermarket flex plates that are cad or zinc plated suffer from hydrogen embrittlement cause by the plating process. They can be "baked" xxx*s for x time to remove it and prevent it from happening. Few manufacturers do. Having this happen on a "stock" unplated flex plate ( to me ) screams torque converter imbalance to some degree. It is certainly not rotational torque issues.

Did you have this ring on it when you took it apart? Supposed to help spread out the load to prevent cracking.