Repair of Broken Body Mount Bolts at Firewall

[gmtofd]

My daily driver Malibu had a broken body mount bolt on the right side at the firewall. Body flexing resulted in a cracked windshield at both upper corners. Of course all the mounts should be replaced on a 39 year old A body that has over 237k miles on it, but that job will occur once it is possible to lay the car up for more than a weekend. Just wanted to repair the immediate body mount problem, so I can then get a new windshield installed. Fortunately the firewall mounts are the easiest to get at as there is a "window" build into the mount's housing. This window allow removal of the cage nut.

How it is possible to remove the cage nut is to heat the broken stud from the frame side while grabbing on the stud with a pair on needle nose vise grips that is accessible though the "window". Using my old oxy/acy welding torch setup, once things get hot enough, it was possible to free the cage nut from the mount housing. Then it is just a matter of removing the stud from the cage nut. The original upper mount between the frame and body will be retained for now, but removed prior to heating up the mount housing. One other thing, the body mount will not come out until the body is raised a little. I used a really big screw, (it's really big), wedge between the frame and body and that leverage was enough to raise for the needed clearance, but a floor jack place under the body along with sufficent wood to spread the load would work just as well.

 

[pontiacgp]

There is not much access in that location but I suggest you break the cage nut and remove that so you can use a bolt, washer and nut. I doubt that one broken mount can be attributed to the body flex that caused the windshield to crack. I think you should park the car and remove the body to see what's going on.

 

[TURNA]

I use a stud remover socket on the remaining broken bolt along with a good dose of PB Blaster

 

[ItsnotaGN]

My #2 body mount bolts looked like stalactites, they broke off immediately. Some PB Blaster on the cage nuts and a vise grip removed the remaining studs. The bigger problem is the frame was rusted at that location and needed to be fixed. Also the tensile rating on the body bolts is a 10.9, pretty much the metric equivalent of a grade 8.

 

[565bbchevy]

When I read this I thought the OP was just stating how he had done the job not asking how to do it.

 

[pontiacgp]

When I read this I thought the OP was just stating how he had done the job not asking how to do it.

re-reading it I think you may be right, he is asking and answering his own questions....

 

[gmtofd]

That's correct, thought that I would contribute how I was able to remove the right side firewall cage nut.

One of the posters stated that there may be more going on with the body mounts than just the right side firewall mount bolt being broken. I'll have a look to see if any of the other mounts are loose to the point that it is possible to move the lower cushion as was the case of the mount that was repaired. Thanks for the comment.