How to remove spinning rivnut?

[ecarnell]

I’m in need to remove my aluminum skid plate – last time it was off was 2 years ago. Been doing top side/Pela oil changes and haven’t had to go underneath.
I’m planning on doing struts in the near future – and have a small exhaust rattle that I need to investigate – but the bolt for the skid plate on the rear driver’s side just spins…..
Worst case I can notch carefully the skid plate and remove all the other bolts and slide it out – but I’m open to any other ideas.
I’ve tried to lift car /compress the skid plate around the rivnut – but the added pressure still isn’t enough to stop it from rotating.
Tried hammering in a screw driver – but no success.
Tried impact and wrench – still spins.
I am thinking about trying to drill through the washer – into rivnut and frame in order for it to stop rotating (enough clearance to get a socket around the bolt head) – made screw in a bolt to stop it from rotating?
I would rather not resort to cutting off the head of the bolt – and dropping it that way – as I want to make sure I have enough bite to remove the bolt (but may have enough shank left on the bolt that I could get a pipe wrench around it.
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Any other bright ideas?
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I plan on getting all of them tack welded in place – to prevent this from re-occurring on any of the other ones……
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[KMWilliams]

I vote for cutting the head off the bolt.

You tried everything I would do first.

 

[runonbeer]

Just drill the whole thing out. You'll need to replace that rivnut anyway since it wasn't installed correctly.

 

[CBS06]

yep they spin, PITA-- cut it off , vice grip it out , New riv nut , I Tack welded one spot. Made sure rivnut was tight- made sure bolt was not to tight in rivnut -tapped it out a little. Longer bolts added polyurethane sway bar end link bushings $8 to the rear between frame and plate. rattle gone and it comes apart a few times a year for cleaning and re anti seize.

 

[ecarnell]

Not much - can just hammer in a large flathead screw driver - pushing/compressing the small rubber washer in-between plate and rivnut.