Possible balance issue, or just unlucky?

[Valvebounce]

I did some racing last weekend.
Motor threw the fan and powersteer belts. On the last pass, it also lost one torque converter bolt, and stripped the helicoil on the opposite side.

Motor is a stroker.
Given that there were issues at both ends of the crankshaft, could an imbalance issue be playing a part?
The people who supplied the stroker kit advertise that they balance them to 1gram.

I've had other cars where breaking flywheel bolts, and having flywheel bolts shake loose was a common problem. (Even when the bolt holes where tapped out, loctite primered, and loctited in)

The crank had a number 5 main journal that was 1 thou oversize when the kit arrived. So I do have to wonder how much care has been taken?

 

[MrJLR]

It seems more likely that when one scattered, it cause the in balance on the other end.
Sorry to hear about your carnage.

Jeff

 

[nm9stheham]

If the crank and rotating assembly was out of balance and caused these 2 issues, then I expect you would have felt the vibrations long before the drag strip visit. Do you have any evidence or feel for an imbalance besides these 2 faiiures?

Without other evidence of imbalance, I would be inclined to attribute the causes for these 2 failures to things like pulley misalignment or overspeed belts, and the threads failing in the TC block, or similar issues.