The flex plate should bend slightly, hence the name "flexplate". The convertor nuts won't have an effect with the movement of the flexplate since it is rigidly mounted to the engine's crank. If the convertor nuts were loose, the convertor would move back and forth, but the flex plate would stay still. You'd have some interesting knocking sounds at idle if the nuts were loose.
Move the flex plate in and out again, and see if your harmonic balancer is moving in and out too---if so, then your engine's thrust bearing is shot. I have seen cars at the shop with a lot more then an 1/8th of an inch of thrust clearance, and they drove normal.
My Ford book recomends .004-.010 thrust clearance with a max of .012. If your measurement of .062 is accurate, then it sounds like time for some bearings, or complete engine overhaul.
Yet another possibility for flexplate movement is a cracked flexplate. It happens more than you'd think. Of course the only way to be sure is to separate the engine from the trans and visually inspect it.
Thanks for the info! I rotated the flexplate and gave it a visual and did not see any cracks. I will check the harmonic balancer for movement. I suspect it due to wear but I will also try to check the exact clearance, felt like 1/8 inch but who knows until you actually measure.
Like Cougrrcj says, it is common for flexplates to crack. When they do crack, 90+% of the time it is around the flex plate to crank bolts---which you can't see from the starter hole. With that being the case, you have to pull your tranny out to visually inspect.
Sometimes with a cracked flexplate, you'll hear a metal on metal tapping sound. When myflex plate cracked it only made the sound when the motor was cold because the two pieces on either side of the crack would rub against each other. When the motor warmed up, the flex plate would expand like any heated metal and the crack would then have enough clearance to not rub on itself.
I drove all the way from south Florida to New York---blazing through some of the way. The next morning in New York, is when I heard the sound. I drove the rest of the way to Massacusetts and when friend and 70 Cougar owner Pat Bauchamp helped me swap out the flexplate at his huse in RI, we saw that the crack extended in a 350 degree circle around the crank bolts. Amazing that it didn't fully break, becase I was beating on it as I neared it house---ha ha ha.
Well, I "monkeyed" around a bit more and was able to check the amount of movement a little more closely at the harmonic balancer. The measurement I got was 3/32 "....so that's about .09375.... a "little" over spec, lol. I guess that puts a cracked flexplate issue to bed? So I need a rebuild ...OK...but how soon should I do this? Is this something that can cause a breakdown or is it just going to make a bit more noise than usual and/or leak oil ? I wasn't planning a rebuild right away, hoping to drive it at a leisurely? pace for a while yet. Thanks for your help.
It's either pay now, or pay later. How long ago was the motor rebuilt? Ever? Well, if never, then it has been wearing since the day it was new and has been at this excess of clearance for quite some time. I'd say if you drive it leisurely, just go with, and run 20w-50 oil.