This came up after a heated conversation with a scrutineer last weekend who said he wouldnt sign off on any bike that made good hp that had a sharkfin attached via drill/tap/helicoil to the swingarm. I didnt pursue it as wasnt my bike and had already been through, but that's what I've done as per instructions provided as much as I didnt enjoy doing it. I have no bias either way, but out of interest has anybody heard/witnessed a failure of a swingarm where the sharkfin was installed via drill/tap/helicoil?
Our AMA bike was done that exact way. We did have the fin come loose during practice, only because someone forgot to put some loctite on the bolts, but the helicoils were in solid. Maybe the tech person was having a bad day.
Local club racing level. I've never seen them damaged around the sharkfin, I'll def catch him up next time to discuss.
IOM scrutineers are about the most thorough and strict tech inspectors you can imagine, and I'm pretty sure they not only pass that but require it.
To answer your question no. People drill holes in far more dangerous places than that, think bars. Inspector was a quack, or he "Polentoed" and wants everyone to be like him.
The swingarm on my ex-Parts Canada SS bike is drilled/tapped (no insert). I pulled the fin off swapping swingarms (about to go drill the new holes today, actually), and it was in for four years with red Loctite. I plan to use the same method. No nutserts/heli, just straight tap and red Loctite.