Hello,

I'm mid-way through replacing all the body mounts on my 1980. The project was going (reasonably) well until I hit the #3 on the passengers. As many threads on this forum talk about I spun the nut in the cage even after PB Blasting for a week. It took very little force for the nut to spin so I think the nut was rusted to the point where its points are rounded. I cut the head of the bolt off and was able to lift the body sufficiently to get to the flange and cage on the frame. See picture below.

I've ordered the new mount bracket for this location which incorporates the caged nut and I plan to find a mobile welder who can weld the new one on. I know absolutely nothing about welding and this type of metal work so please excuse the question if the answer is obvious but how do I get the old body mount bracket off that is welded to the frame, and do the least amount of damage to the frame? Without knowing better I'd just take my 4-1/2 in. angle grinder with a metal blade and start grinding it away but is there a better way to do this? For example, might an SDS hammer drill with a chisel bit break it free or would the concussive force cause more potential harm?

Thanks in advance for any suggestions! As a first timer doing body mounts this has been quite an adventure. This forum and the generous advice of experienced members has been invaluable.


This is the #3 body mount bracket I need to remove. Taken from the rear passenger wheel well looking to the front of the car.

 

Why did you choose to replace all the body mounts ? Rust ?

As for this #3 and no welding experience you're in a pickle. You may be able to use a sawzall but replacing it is gonna be interesting.

Good luck.

 

It started with me discovering that the #4 driver's side nut and cage (inside rear corners) had rusted to dust and the other side wasn't too far behind. I did some reading and felt that the only way to replace #4 was to lift the body one side at a time about 4 inches. In order to lift the body I had to loosen #1, #2 & #3. While doing that I discovered the rubber was totally perished in the #2 locations on both sides and pretty bad elsewhere. I also found fairly bad rust on the body side of the #2's behind the kick panels (the body side and floor pan is metal on 80's not fiberglass unfortunately). Not terminal rust but definitely in need of stabilizing otherwise the top bushing inside the car would eventually pull through to the frame below.. At this point it just made sense to do them all and replace with urethane. The job actually went relatively well until the nut on #3 passenger side broke free of the cage.

I've found a guy who says he can weld the new part easily enough. You can buy the flange with the nut and cage inside it for about $40 (see pics). I wanted to remove the old one before the welder arrived but am not sure how to. It might break free with a chisel or else I guess I can just grind the welds off?

Photo's courtesy Corvette Central.

 

When I replaced that same mount, I cut one of the welds (it was only spot welded on two sides) most of the way through it with a cutoff wheel and then popped it free with a ~1/2" chisel and hammer. Once it popped off, I ground the remaining weld down in prep for welding in the new mount.

 

Drill out the spot welds and use a cold chisel to remove it. Grind off the remaining weld and an area to clean metal for your welder to use. Easy and they will thank you.

 

I would start with an angle grinder and then any pieces you can't get to with the grinder finish with a chisel.

Richard

 

Makes sense, thank you!

 

Thanks for the feedback. I started with my AG with a metal cut off wheel and it came off fairly easily in the end. Mine was more than spot welded, I had bead welds on three sides but not terribly hard to cut off. Looked like a lot of spatter so I guess someone had done it before or there was a new welder at the factory that day!. I did gouge the frame a bit in places trying to get the right angle to cut but it all cleaned up ok with a wire wheel. By the way for anyone else, a 4-1/2 grinder is too small to avoid the frame. You have to some down an angle to avoid the body of the grinder hitting the frame which cuts the frame. Use a 7" so that you can get the blade completely parallel to the frame tube and cut under the flange of the boxed nut.

 

leave it there until the welder gets there. he is in a better position to decide what and how much to cut. you want the new mount as close as possible to the height of the old one. the new one may be a little shorter which may be better off attaching it to some of the remaining mount for height.

 

High speed cutoff wheel and an angle grinder. It will take about 5 minutes.

Lars