Body-off underway, bolt seized

[Ed's 1970]

Hi all,
The body is almost ready to remove from the chassis. My chassis has some rust and I decided to redo it. I am going to be installing a 540 big block, so all has to be right. Everything has gone great so far. I was successful on 7 of 8 chassis mount bolts. The only one which has given me a problem is the very back one on the driver side, at least it looked easy. I used about a 3 foot cheater bar and it broke loose. Unfortunately, I broke the factory bolt which is somehow spot welded inside of another steel part and the bolt just keeps spinning. U can get access from inside the car in the very back, barely enough room to do anything. My plan is to just grind the head of the bolt off so I can get the shell off and deal with it later. I can not believe the factory installed something like this so flimsy instead of using just a regular nut and washer.
Has this happened to anyone else and any ideas what to do?
Ed

 

[topless82vette]

try another method

 

[LVMYVT76]

can you get a saws-all on it???? Just cut the bolt. Replace all bolts. Keep the shims to each bolt and mark them.

 

[rgtrough]

Hey Ed, this happened to me also. I ground off the bolt and nut and then lifted the body off. Getting into the rear compatment to retrieve the rest of the bolt has not been attempted yet.

peace Bud

 

[6880 Mike]

...I can not believe the factory installed something like this so flimsy instead of using just a regular nut and washer.....

The caged nut worked fine for assembly purposes. GM wasn't expecting future Corvette owners to be doing frame off restorations after nearly 40 years.

 

[Ed's 1970]

It appears that the factory riveted on some sheetmetal to the fiberglass body, and this is where that "caged" nut is located. So, if I can't drill the bolt out to repair it, which i should be able to, I can always remove that sheetmetal housing by removing the rivets. Anyhow, I guess I am not too worried about it after all. It is kind of tight for a grinder, but can be done, a torch would be better but I don't have one. Too bad the factory didn't put on some antiseize compound on the bolts, I don't know if they had antiseize back then or not. I will be putting a little antiseize on the bolts this time around.

 

[6880 Mike]

...It appears that the factory riveted on some sheetmetal to the fiberglass body, and this is where that "caged" nut is located...

That's a factory reinforcement. If memory serves, Corvette Central carries replacements and you can probably get them from other Corvette vendors.

Do you have the assembly instruction manual? The AIM shows everything you've beein running in to so far and would be a help to you.

 

[LVMYVT76]

I wouldn't use a torch, fiberglass burns really easily!!! and so does rubber mounting cushions.

 

[Ed's 1970]

I wouldn't use a torch, fiberglass burns really easily!!! and so does rubber mounting cushions.

Well the bolt head is surrounded by steel. The body mounts are solid, it's a 1970.

 

[LVMYVT76]

You can't slide a saws all blade between to cut the bolt?

 

[GerryLP]

... My plan is to just grind the head of the bolt off so I can get the shell off and deal with it later. I can not believe the factory installed something like this so flimsy instead of using just a regular nut and washer.
Has this happened to anyone else and any ideas what to do?
Ed

The factory usually does not plan for their products to last a long time. They counted on you to just go buy another Vette...

GerryLP:cool

 

[Ed's 1970]

You can't slide a saws all blade between to cut the bolt?

Thanks for that idea! I will try it, I don't know if there is enough room for that. I will get that bolt head off somehow!

 

[topless82vette]

The factory usually does not plan for their products to last a long time. They counted on you to just go buy another Vette...

GerryLP:cool

This happened on mine when I did the convertible conversion. But I recall I did the opposite of what you are doing. I took some vice grips or a pipe wrench and dont ask me exactly how I did it. But I took and tightened the bolt till it snapped then dealt with it by removing the inside braces this bolt is associated with. I would have to look at my car then could tell you how I got the rusted bolt out for sure.

 

[Ed's 1970]

Well just a follow up. I was able to grind the bolt head off no problem. For the first part I used one of those air powered 3" cut-off die grinders, but it did not fit all the way within the steel frame. The rest I just grinded off with an angle grinder. The complete fix I was told is to go inside the car and chisel off the rivets that hold the square steel nut to the body. Supposedly they are easy to take off since they are aluminum rivets.

Turns out I had problems with another bolt. I was able to loosen it but would not come out. The one in the wheel well on the passenger side. I ended up cutting a small piece of fiberglass off on the bottom to gain access and then used a tiger (recip) saw to cut the bolt head off.

Now the body is ready to lift off.