Question? My drive coupler sheared all the bolts completely off my flywheel and shattered my bellhousing is this a alignment problem or did the bolts possibly work loose due to vibration? Drive checked out good with the exception of the front drive seal that is leaking. Any idea why this may have happend?

If the bolts came loose than the bolt holes would be damaged, Plus they wouldn't all come loose at the same time.

How long has the coupler been on??????? Sounds like they were not properly torqued.

Where the bolts sheard off right under the head or did they shear off with some length to them? That would tell you if they backed out or not.
I use grade 8 bolts for that, did some one use junk??

Just some thoughts.. let us know.
Dick

There was an update to the bolts that hold the coupler also. The new ones have a slight taper under the head to help align the coupler. Don't know what year your unit is.

SHS-05-01 01/19/2005 Engine Coupler Fastener Change

Thanks you guys for your input if you have any more ideas why this may have failed that would be great!!! Two or more heads are always better than one!!

Once one or 2 bolts get loose, the others will soon follow and bolts will start breaking.

Does anyone know why this might take out the input seal on my drive?(too much reciprocating mass with the driveshaft off balance?) and as far as I can tell that is the only damage to my drive.

Thanks GRIFF what you said makes sense!!

What does the damage seal look like? Is this an XR drive? They have an updated retainer that has a lip to keep the seal in place. The first ones were being pushed out by pressure build up in the drive.. The kit fixed that problem. If it is an XR, that could be the reason for the damaged seal and not related to the coupler problem.