i just rebuilt my neighbors 351W in his 94 F150. The transmission was also rebuilt not that long ago. I finished getting the truck together today, but when I test drove it, it vibrated real bad when the transmission shifted and the converter locked up. The converter is not that old, and it didnt shake before the rebuild. When I was installing the transmission, I bolted the transmission up and went to bolt down the torque converter but realized it was binding due to not being seated all the way into the tranny. I backed off the tranny and seated the converter the rest of the way in. Could that have damaged the converter enough to cause bad vibrations. It doesnt shake through first or second gear, just when it goes into third or OD and the converter starts to lock up. It also did it a little when it was in reverse at idle, but it went away during acceleration. I know its not caused by the engine, or the driveshaft. It doesnt matter what speed or RPM its at, only when the converter locks up. Any help would be appreciated, Mike

 

The converter drops back 3 times when installing,when you were turning it are you sure it went back 3 times to bottom out?Dont see how what you did with the install at first could of had anything to do with it.

 

I think the converter dropped back 2 times when I first tried to install it. I was going to check it with a straight edge across the bell housing, but I was in a hurry and just eyed it and thought it was in. I bolted the tranny up and I couldnt turn the engine over by hand to get to the converter studs. Thats when I realized it must not have been in right. i dropped the trans back out and the converter dropped in one more time, so I know it wasnt seated.
I pulled the plastic cap off of the bellhousing and I took off the metal shield to gain access to the flywheel and converter. While it was running, I looked for anything that might be visible at the flywheel. I can feel a slight vibration at idle, but it goes away when I give it gas. It looks like the flywheel has a tiny bit of wobble to it, but hardly noticeable. The main vibrations that cause the shaking comes in third or overdrive when the converter starts to lock up. What can be damaged during install if the converter is not seated all the way. Im hoping its just the converter damaged. Could not being bolted down perfectly cause the shaking. It shakes really bad at converter lock up. Im going to pull the trans out this weekend, is there anything I can look for before I take it to the trans shop. Thanks, Mike