At one point or another you may have heard a grinding noise when you went to start your cars engine. In most cases this is caused by damaged teeth on the flywheel or flexplate. A flywheel can be repaired but a flexplate will need to be replaced. Automatic transmissions use a flexplates where a standard shift uses a flywheel.
Detecting a problem with your Flexplate
A flywheel has teeth that can be damaged similar to the flexplate but the flywheel's teeth can be removed. These teeth are know as the ring gear. If the teeth on the ring gear are damaged it should be replaced. Also the surface of the flywheel can be damaged caused from friction of the clutch plate material or lack of. If any groves are noticed the fly wheel should be resurfaced before installation. The last thing to look for are what are know as "Hot Spots" that will cause the clutch to chatter or vibrate when using it. This is a slight warpage and can be visually seen by slight discoloration on the flywheel surface. The color of the surface will have a purplish tint in areas where the surface has gotten hot. This can be caused by hot rodding and or riding the clutch.
If you find that you need to replace the ring gear, follow these simple steps. Using a propane torch, heat the ring gear in one spot till it turn red. Then move the torch side to side passing over the red spot further and further away to make a larger area red. Continue heating till the opposite side is to hot to touch. Then support the flywheel on a block to where you can smack the ring gear off with a hammer. Clean the flywheel, Heat the new ring gear this time covering the entire outside until you can set it completely down over the flywheel. Note* it will cool fast and be extremely tight on the flywheel, so make sure to get it seated quickly.