Never had this happen before.
Red loctite, new Flexplates, new ARP converter bolts and after 3 passes, they are loose again.
I whacked the hell out of them with a sledge hammer with a 3/4" 12 point wrench like I always have done and never had an issue before.
What could be the problem?
Maybe I need to send the converter back to change the pads on the converter.
It's a turbo action 8"

I had a bad fluid dapner ,it was cracked and was leaking the viscous fluid out of it. the bolts would come loose after two passes.it wound up cracking my crank ,it started wiping out the thrust bg.i changed the crank and put a ati dapner on it no more problems.good luck.

Harmonics or vibration come to mind.......

Conv or the engine out of balance... did you degree the trans

Just for posterity, what made the FD crack and where was the crack.

Cartainly balance issues can make converter bolts come loose. I have also seen detonation do it, and pushrods that were flexing did it, but when the pushrod issue was going on, the adjusters wouldn't stay tight either. That one was a bummer to track down.

I had a alternator on it it cracked where the pulley was bolted to the crank never saw it till I took the pulley off.

LOL!!!

Detonation. Harmonics caused by detonation or anything else.

I like that answer best...ole Tom has a few words of wisdom every once in a while!!

We went through this on a short block that was supposed to be balanced. No noticeable vibration and the engine ran great. Brought the rotating assembly to a more reputable shop and it was quite a bit out of balance (don't remember the amount, but it was significant according to the machinist). After it was rebalanced, the problem went away. That is the only thing we changed.

This is what I am thinking it is too.
Going to check the ATI balancer today and see if its tight and if theres any cracks in it.
I remember it was tough getting it off last year before the rebuild. Hope I didn't hurt it fighting it off the crank.

Do you balance your slicks or are you one of these guys that say it isn't necessarily? How's your pinion angle and what is the run-out of your driveshaft?

Had a 727 input shaft with a slight bend do that till we found it!

We had the same problem . New build and 1st time ever using a trans brake. Was leaving off the brake in the low 3000 range and the bolts would come loose . Stepped it up to 4800 no problems again .

AJ and I discovered a problem with the full round B&M flexplates that cause the bolts to come loose.The flexplate does not tighten up flush with the converter pads it contacts the inside edge of the pads or lugs and the bolts no matter how tight will not conform the plate to the pads,the bolt as well as the pads only make contact on the inner edge.We checked the pads and they are flat with the converter and starter ring.The 4 leaf clover style plates have enough flex to set flat on the pads when tightened.Look at you plate to see if it contacts the entire pad.