I found a bumper in pretty good shape on eBay for my 1961 Olds 98. I am in the process of removing the old, dented one. My gramps was rear ended pretty bad in the early 90's and it's a mess, so I want to at least get things removed to see what I am truly working with. There are 2 large bolts and nuts (7/8" socket) on both left and right ends on the underside of the vehicle, that help hold the bumper and bottom metal trim (not sure what to call the lower piece that has the backup valences in them and the license plate) on the car. All four have been a pain to remove and I am to the point where the bolts merely spin, while the nut is rusted onto them. The bolts seem like a carriage bolt, with the rounded head and below that, a square shank starts before the threads, to lock it in place and keep it from turning. Well, the square part has either been shaved to a circle, or the hole it was sitting in has been rounded out and can no longer hold the bolt while I try to remove the stuck nuts.

What is my next best approach? Cut off wheel and cut off all four bolts? Tight clearances to get a grinder under there. I've tried wedging things in there to try and stop the bolt from turning but no luck. The bolts simply spin. Any ideas? See the pictures. Thanks all!

Passenger rear corner. The but has been removed to a point but will no longer come off due to the bolt spinning.

Lower nut.

Both 7/8" nuts, passenger rear corner.

 

Maybe a nut splitter would work for this.

 

Place a screw driver into the shot.
and apply pressure.
Or torch

 

The bolt is a carriage bolt with a square feature that is restrained in the slot as you tighten the nut. You need to hold the head of the bolt against the slot to restrain it. I've had luck using a large screwdriver between the washer and the bracket to do the same thing.

 

Since its already junk I would torch them off. It would take <5 minutes.

 

The hole that the square part of the bolt sits in is no longer square; it has been rounded beyond round. The nut is ON there. Rusted for years. At this point, since I don't own torches, how does a small 3" cutoff tool from HF sound for cutting through these bolts?

 

The cutoff tool will work fine.

 

Happen to know a carpenter (or other) friend w/ some tools? I own a Dewalt Oscillating multi-tasking saw/tool. Accepts wood & metal blades - would saw through that bolt in seconds.