There is a center section in the middle of the flywheel for torque limiting, and it can slip when you guys turn these trucks up.
They also can slip at lower power levels when hot or worn, but yes, turbo power levels are much harder on the silly things.
In the case of my '93, even at 250RWHP(more than you can get with a cranked up pump) I had no slipping issues... *until* I finally got the thing hot by driving 3 hours with an unloaded trailer.
(I'd driven with a /loaded/ trailer multiple times before that, but only 1 hour or less without issues).
edit:
Also, with my '92 - When I picked it up, it "needed a clutch". It slipped at barely above idle, though would get to 60 if you were really careful.
Pulled the DMF(which had been replaced maby 10 years before? It was an aftermarket one)
The friction disk was fine, the ball bearings were falling out of the bearing race, and I'm pretty sure the torque limiter was the failure point there.
And that truck hadn't been turned up much, considering it still had the torque limiter screw in stock spot and still had fuel screw adjustment to be made(made like 150rwhp on the dyno a bit later with maxed fuel screw, then cranked the torque limiter back out and made 200rwhp)
To the original thread starter, Ford did not install these dmf flywheels to aggravate all their truck owners and make them spend gobs of money years down the road, though it would seem that way. They installed the DMF system because of noise generated in the zf 5 speed by the diesel engine. Most likely you will install a conversion kit that converts your truck to a solid flywheel, if you find a DMF if it is pretty expensive. But be warned you may get some noise at idle and certain conditions from the trans. It will sound like it has gravel in it, but there is not a thing wrong with it. Some trucks are louder than others, but you will get some noise from it.
Yeah, true. Part of the solution is that the LuK SMF kit has two rows of springs in it; it seems to make a big difference.
The other thing you can do is add an extra quart of ATF to your 5-speed(through the top). This helps quiet it down, and I've never heard of anyone having issues from it.
Also, adjusting your idle speed a little can have a big impact - if it happens to hit a harmonic at idle, that's when you get the really bad gravel noise at idle. Adjust it up or down so it doesn't hit that speed, and it'll quiet it down more.