What would cause my flex plate or flywheel to keep breaking in a 1999 Pontiac Grand Prix SE?

Improper installation, a warped or out of balance torque converter, any type of power train misalignment can put undue strain on the flex plate. Also shifting from forward to reverse while the vehicle is still in motion has been known to cause all types of drive train problems. I hope this has helped you a little and good luck with your flex plate problems. One other possibility, if you are using salvage yard flex plates a NEW one properly installed should solve your problem.

If your crank end play is excessive then it might cause breakage,but I have worked on hundreds of your make and have never seen this,IF you over torque it MIGHT crack once,but not multiple times,not trying to drag race a family car,?

i have seen this problem only once in a 2000 GP. After carefully inspecting mating surfaces of engine and transmission, i had found a small amount of corrosion around one of the centering dowels. This (in my case) was enough to keep the engine and tranny from being perfectly square to one another. This job was done twice before at another shop, they must have missed it. After a bit of cleaning surfaces and installed a USED flywheel, the problem never came back. I may want to mention, the flywheel was breaking when speeds of 140kms(90mph) were reached. (highway)

I have a 2002 hond accored and my flywheel already has broke twice i need to find. The problem quick so that stops happening