Banging transmission

[dcdave]

Put a rebuilt transmission in my 78 F250 C6.

Pretty sure the converter was lined up in the pump and I used the bolts to ease it out onto the flywheel. Fairly certain I have it installed correctly.

Problem - Cranked the engine and about every half second there is this "muffled bang".

Anyone know what that might be.

Pretty sure it isn't drive shaft u-joints. It's very clear it's comding from the front area of the tranny.

One thing just in case this is a clue :-) - I have this nagging feeling I have this nagging in my head that I forgot to install the shaft between the converter and the tranny. I can't see myself doing it in my memory anyway. I have the shaft from the old tranny and no other so I guess the question is when you buy a rebuilt and the converter is installed there is a shaft in the new one right? :-)

If the converters were different could this cause this? (don't know that they are, just thinking.)

[archangel]

If the trans was assembled, it should be there, and I doubt there would be a bang if it were out.

Did you check the flywheel for cracks, make sure the converter nuts are tight, see if anything is hitting the flywheel, and be sure the studs do not stick out too far as they could hit something on the back of the block?

Also, after the bell housing is bolted tight to the engine block, the converter studs should still be able to turn back and forth a little bit in their holes before the converter nuts are installed and tightened.

There is the possibility something in the trans is hitting something else.