1994 Ford Aerostar 6 cyl Two Wheel Drive 177000 miles
I recently had the 4 speed stock transmission overhauled by a mechanic who has experience in this type of repairs. We both installed it with a kragen -remanufactured Flex plate and rebuilt torque convertor. It ran well and shifted very well for about six months and then while going up a small grade it broke down. I took off the transmission and the problem was the flex plate sheared at the bolts next to where it attaches to a small spacer and hub on the crankshft. The pilot bearing and hub is not worn out as it fits the torque convertor very snug.
However when I first installed the transmission, I did notice a very slight vibration when filling it up with oil at idle speed. Why does the flex plate shear? Do I need to use FORD original equipment parts for the flex plate and Torque convertors? What do I need to do to solve this problem?