Join Date: Aug 1998
Location: Waldorf Md. USA
It sounds as though you might not have had the torque converter all the way back into the transmission ? When the converter is installed correctly, you should be able to pull it back away from the flywheel about 1/4 inch or so, or at least enough so that it is not touching the flywheel. If it is not into the front of the transmission all the way, it will be forced against the flywheel and it will not only end up breaking the flywheel, but probably ruined the front pump in the transmission also.
You also have to make sure that the converter goes at least part of the way into the back of the crankshaft. YOu should be able to pull it forward up against the flywheel without forcing it. This will also cause a broken flywheel.
If you had the first problem, I would recommend that you take the trans to the builder and have him examine the front pump for damage, and also show you how to properly get the converter all the way in, it is a bit tricky if you have never done it before.
If you had neither of the above situations, then I am not sure why the flywheel would have broken.
Hope this helps,
Advanced Automotive Machine
1971 Chevelle "Heavy Chevy" original owner
1973 Z-28 ..one family car...Brother bought it new in 73