Originally Posted by DIYMechanic
The sound is the best way to tell is a DMF is on nits way out. Generally when they're starting to get loose they will exhibit a distinctive "clack, clack, clack" sound when you shut off the engine. What it is, is that the back half (Flywheel portion) of the DMF is getting sloppy and bouncing back and forth against the dampener springs when the engine stops abruptly. If you're hearing that, then now would be a good time to get it taken care of before it comes apart and wrecks the trans.
If the truck is more or less stock, you don't need to spend that much on a SMF conversion. A very nice LUK setup (which I highly recommend for a stock truck) will only run you about $275 on Rockauto. And it includes a new SMF, the disk, the throwout bearing, pilot bearing, pressure plate, and all the hardware. A great deal on a good clutch and as long as you're at or near stock power levels it will work really well.
More Information for LUK 07226
Originally Posted by farmert
If you can rotate the DM flywheel back and forth more than 5/8 of an inch rather easily, it is on it's way out. Also it will have a vibrating rattle on shut down of the engine. It has a bearing in the center of the flywheel that can go bad, and it will give you a terrible vibrating shake from the tranny while driving. If that is the case, the tranny isn't long for this world, as it will crack the bell housing on the tranny. The conversion kit should be had for less than 1k for the kit. IIRC they run around 675 depending on the kit.
Thanks for the link on that LUK... seems like a good way to go. Truck I'm looking at has an aftermarket exhaust but I don't think any crazy mods, and for the time being my trailer is probably <5klb so it wouldn't get worked too hard anyway.
Did not notice any unusual clatter at shutdown, and no vibration up to at least 45mph, so hopefully it's either SMF or not an immediate problem, but I will try to inspect once I can get it in my shop.