I have tried to loosen both Right Hand #3 and #4 body mount so I can adjust the gap on the door.

Good news is that with a jackstand under #3 the door gap opened up about 1/8" when the car is in the air. #3 body mount bolt came loose really easy. If I can remove a shim from under #4 then the gap will be real close and I can take about 1/16" of the centre rear of the door to get it nice.

Bad news is #4. I saturated the #4 for 2 days with PB Blaster from the top (I think the nut is under the RH spring for the deck lid).

#4 bolt turns and it sound like the nut is turning.

Question is: Is this nut a nut? or a body nut that was supposed to be riveted but it has broke loose?

Thanks,

Pete

 

Body mount #4 is a caged nut. The cage is riveted to the body, and in most case, the rivets have long since corroded away and the cage and nut spin. You need a second person to hold the cage inside the car while you turn the bolt outside.

 

Bruce,

I figured (and was afraid) that was the case. Now I have to take the decklid off, remove the deck lid spring and get to that stupid nut.

Let you know how I go.

Pete

 

I just cut my bolt off under the car. This freed the nut and cage to come out of the top. If the cage is spinning (with the nut) you need new mounting hardware anyway...do you really have to remove the decklid?

 

I may get away with not removing the decklid but I have to remove the spring that holds it up anyway. Will be alot easier to remove the spring if there is no wright on it. If the LID is out of the way I can work on the hinge/spring and see what is going on.

I didn't think of cutting of the bolt. That is an option though.

Did you do this on a convertible or a coupe?

Pete

 

Pete...it was on a coupe...hence the question about removing the deck lid. I had 1 of the 2 back there spin the rivets off. So I just used a grinder with cutting disc (2 or 3") and cut it off above the head...hope this helps...just don't cut into the mount welded to the frame. It took me about 30 minutes

 

I wish I had a coupe for this job. The vert has a spring and the hinge for the deck lid right over the top of that stupid caged nut. Even if I cut the bolt I still have to take the spring out to remove the bolt/nut from above. Another C3 challenge.

At least I have started though. I was too chicken to start on the door because I knew something like this would happen. Hate it when I am right!

 

Peter: You have to remove the decklid (and springs, hinge assembly, etc.) to get to the interior #4 body mount cage nut on a C3 convertible. The cage nut is in the corner interior area under the entire hinge assembly.

 

Patrick,

Thanks. I am going out to do it now. I better take some pictures for the others that follow in my footsteps.

Pete

 

I'm doing the exact same thing on my 71 Convertible today. Got one #4 mount out. Had to cut the bolt head off and remove the deck lid hinge w/spring. On the other side the bolt spun so I cut the head off. Unfortunately the cage is still in place over the top of the mount and now I can't push it out. I'm going to have to pull the spring on this side too.

Anyone have a trick for getting the deck lid hinges out? The top two bolts are virtually impossible to get to. I got one out with a distributor wrench and a lot of bad language. Any hint on removing the hinges would be great. Also, how do you get the mount cage out if it's still attached but the bolt is turning free?

Pete,

I don't mean to hijack your post. I figure you're going to have the same problems or you'll have a great solution to share.

Thanks,

Whiplash

 

Whiplash,

I have another post with pictures. I cannot find it but here is the scoop.

The spring has to come out before you remove the deck lid hinge. You need to either pry it off and pull the spring out in its compressed state or jam some wood (think door shims) between the coils when it is expanded to keep it around 5.5" long (coils, 7.5" total length). A pry bar will get the spring out without wedges. To put it back in you will need to expand it (I used a vice) and put a bracket on it to hold the coils at 5.5". The GM special tool J-9559 details this. I can email you pics if needed.

The deck lid hinge bracket has 3 bolts. Two are easy as you know. The outer bolt is a SOB. You need to get a 1/4" rachet with about a 1" extension and come up BEHIND the bracket to get at that bolt. You need small hands to get behind there. It is a bear to get out.

Once the bracket is out of the way just break off the cage nut. There is no other way to get that bolt out. I manufactured a cage plate for want of a better name. Get some carboard and cut it out the same size as the are of the recess where the cage nut sits. with the cardboard in place push up a pencil from under the car to mark where the bolt would go. I made a 1/8" plate and drilled a hole. Then I welded a locknut to the hole. Now the nut will never turn and the cage will not brake off in future. An alternative is to buy a new cage nut and rivet the braket in if you want to stay 100% original.

If you need pics email me.

Pete

 

I have seen this done as follows:
-grind the head off the bolt
-tap gently on the remaining bolt and hope the mounting has corroded away
-remove the bolt and the cage with a magnet
-drop in a new bolt on a large washer from the top-you must hold your mouth just right for this step

This is much easier than taking the hinge and spring out if the mount is not attached to the fiberglass very well. I did this on my car and it worked out well. If it doesn't come out easy you will have to disassemble, but it doesn't cost anything to try.

 

I had this same problem with a #4. The nut cage for this bolt is attached with aluminum rivets. If the nut is going to be hard to turn, it will shear the rivets and then you have your "spinning nut."

I was really reluctant to remove the spring (especially since at the time I didn't know how.) What I did was to drill a 1/4 inch hole in the "body mount reinforcement." The idea was to push a steel rod (actually a machinists punch) into the hole to jamb the nut and then unscrew the bolt. I think this was a pretty good idea and really could have worked. Anyhow to make a long story shorter, the nut wouldn't turn. When I eventually got it out it was crossthreaded! Someone at the factory must have used an air impact wrench. There was no way it would have ever loosened. I cut the bolt head off, and since I had by now expanded the size of the 1/4 hole, I went ahead and made the hole larger and removed the nut and remaining bolt out the side of the car. Needless to say an approximate 1 inch hole looks pretty ugly.

I've since bought a new "body mount reinforcement." It's part BM98E in the Volunteer Vette Product catalog. When I remove the body, I can pretty much repair my damage! I wish this thread had appeared a month ago.

 

I just removed the body from the frame on my 68 vert. Body bolts #2, #3 and #4 spun on me!

Ended up cutting a grinding.

All the old body mount bushings looked like cement. Not rubber, but cement!

 

That may be because they didn't use rubber until 1973. I had 4 of the 8 bolts rusted in place when I pulled my body. I cut the #1's and #4's off. The rocker channels were so bad that I didn't have to do anything to the #2+3's until after the body was off.
Body-Off

 

My driver's side rocker channel is like that. What did you do to repair them? I also need to repair the driver's side pillar post. Looks like old accident damage.