Replacing front cab mount captured nuts.

[handloader90]

What is the best method to do this?

I sheared both of tiny front cab mount bolts. I was cranking on them with a breaker bar and off the came.

First thought was to drill the remainder of the bolt out and tap the hole. This may still be an option but I'm gonna have to get under that and check it out to see if I have a long enough bit to do it.

I would prefer to just put new sheet metal and a captured nut in and put a heavy coat of anti-seize on everything to avoid this issue in the future.

What has been the most effective way for you guys?

 

[rampage]

Once you get the existing bolt out, you could drill clear through the cab floor from the bottom up the size of the nut, using the existing cab mount as a guide. Then insert the nut from inside the cab and tighten that way. Then plug the hole in the cab with a rubber plug. Just a thought about a cheap easy way to do it.

 

[Truckman4life]

I spun all four inside the body once back in high school. I cut the heads off and then I pounded up on them to dent the floor so I could find them and then cut holes and removed the seized bolt and captured nut. I wasn't a welder or anything like that back then so I just cut some square plates for big body washers and used extra long bolts all the way through with the head sitting on the floor. Worked good for a high school kid cab swap.

 

[diesel4me]

I've had the same thing happen years ago too,did like you did..
I didn't put a new cage nut in the same spot,instead I used carriage bolts and a duobled up electrical box cover plate to cover up the hole I had to make in the floor to get at the busted bolt and drill it out..having the head of the carriage bolt under the mat didn't bother me any..

When I got my '82 GMC in '03,the cab mount up front on the drivers side had no rubber under the frame pad the cab sits on,so the cab could float up and down..the upper half of the bushing was still good,so I tried to remove the bolt,hoping I could cheat, and just put another lower rubber bushing on it,(found one lying in the dirt at the junkyard like new!)...but the bolt broke off in the nut,and I hated to do it,but I had to open up the mint floor to fix it..

I was able to chisel the spot welds off the caged nut,and I had some square nuts off a trailer hitch install kit that were left over,they were more like a hunk of 1/2" thick steel plate with a threaded 1/2" hole,I used that and welded it in with my arc welder..

I used a cutoff wheel to make a three sided cut in the floor to access the nut,then just hammered it back down and welded it back together..
I think GM went a little overboard as far as the caged nut idea..a carriage bolt would suffice and be a lot easier to deal with years later..