Some time ago I bought me that 89 Firebird and started "restoring" it.It was already shacking when I bought it but then I thought the engine wasn t tuned very well cause it had bad spark plug wires etc. So I changed the ignition stuff but the vibration wouldn t stop. So last day I put the car on a pit removed the flywheel cover and had my girlfriend start the engine. Ahmm what I saw was that the flexplate was moving back and forth.So is that normal and if not what could have caused this distortion? All the mounts seem to be OK. Thanks for advice.

 

the flexplate sounds like its cracked. If you leave it alone it will break the flexplate and the center will break away from the outer ring, leaving you with a car that won't drive. I learned this the hard way. If your flexplate is broken, fix it ASAP.

 

thanks for your reply