I've not seen a thread on this, here is a link to a failure of a harmonic balancer on a new Pentastar in an Aussie Grand Cherokee.
The fella that owns it is the brother of a guy I know from another forum.
Understandably he's not a happy chappy (not all the fault of Jeep, the dealer is evidently a bad one)
Here is some from an email conversation regarding it;
"Got a little bit of extra info from my brother & was slightly off on timing. Issue happened in 3rd week of ownership, started as crack in harmonic balancer which then loosened & ground into motor. Car was off the road for 3 weeks due to no parts in country, apparently as its a new model, & refusal to take parts off showroom model or replace car. Originally offered no loan car but after complaints lodged found a commodore omega.
Car was also damaged while in their care, with significant scratches/gouges to front corner of bumper bar which wasnt disclosed on pickup (was after work so dark when collected but noticed next morning) but when asked about it got something along the lines of 'oh yeah we need your car for paint now' so clearly aware of the issue. Now has to be booked in for front end respray.
I'm pretty sure Mark said he was posting about it online but brother wasn't so sure, will see if I can track down a link.
Mark talked to the Vic Customer Service rep a few times who basically told him he's was crazy & what a ridiculous idea it was to use parts off the showroom vehicle.
While the original issue itself may have been completely random the customer service displayed was terrible.