Solved! Snapped Bolt at Body Mount!

[YukonGTmaster]

I sheared the body mount bolt off when trying to remove it. It is the rear drivers side just forward of the rear bumper. I got it turning with a 1/2 breaker bar, and the crack! Can I gain access from the top? 1997 Yukon GT.

 

[89Suburban]

I tried looking up a parts explosion on JCWhitney, looks like they took a shit with their catalog and joined the new age useless fancy ******** website band wagon. Pull the carpet up and see if the bolt shows. If not, it's probably in the body cavity as a "blind nut" and you will have to cut the floor open to access it.

 

[swathdiver]

I sheared the body mount bolt off when trying to remove it. It is the rear drivers side just forward of the rear bumper. I got it turning with a 1/2 breaker bar, and the crack! Can I gain access from the top? 1997 Yukon GT.

View attachment 276167 View attachment 276168

Check with LMC Truck before you cut into your floor.

 

[89Suburban]

Check with LMC Truck before you cut into your floor.

Damn that’s the place I was trying to think of! Good job buddy.

 

[exp500]

When I removed cab on my 87 P/U, the captured nut spun and I had to cut in to remove it. Noticed that those nuts/clips could be a huge future problem so I welded up some plate nuts on 3/16 or 1/4 plate. Then I cut open the "box" section and used an oval body plug to reseal the area under carpets.
Good luck and report your progress!

 

[Joseph Garcia]

If the nut is welded on, can't you drill out the remaining bolt piece, and then clean the nut's threads with a thread cleaner tap? That is what I did 2 weeks ago, when I broke a bolt holding the U-bracket on my front sway bar.

I took a punch and punched a small indent into the center of the remaining bolt piece. I then started with a 1/16" drill bit, and I drilled into the bolt piece through the entire depth of it. I then repeated the drilling with each and every incrementally larger drill bit in my rack, until I almost reached the original bolt's diameter. Then, I took a cold chisel, and collapsed the remaining bolt shell, and with a pair of needle nose pliers, I literally rotated the bolt piece back out of the nut. Then I took the proper size thread cleaner tap, and I cleaned out the nut's threads. It took less than 2 hours to complete.

 

[YukonGTmaster]

I verified that there is no access from the top. I am going to try Center punching the bolt and drilling from the bottom....then thread chasing. I borescoped the captive nut through a hole in the frame. It looks quite rusty and dirty. I tried soaking in penetrating oil as best I could.

 

[YukonGTmaster]

I got some long small diameter drill bits up to size F. I automatic center punched the bolt from below. I used an air drill and gradual stepped up the bit size as I drilled out the Center of the bolt with lots of cutting fluid to cool and lubricate. All went well until the side wall of the bolt chipped off. I ended up using a pencil grinder with a chainsaw sharpening grinding stone, to grind the rest of the bolt down. I ground it until there was enough of a recess, I could start drilling again. I got down to the tap drill size. I bought a Lisle socket set that adapts taps to a 3/8 drive wratchet. I used a 12mm x 1.75 tap. I Cleaned out the hole with air. I bought new bolts from LMC, coated the shank with corrosion preventative paste, and hit the threads with antiseize. I had a good face shield so I didn’t get a lot of shwarf and dirt in my face. Dare I try and remove the rear passenger bolt next!?

 

[drakon543]

well you know how to fix it now if something happens. lots of penetrant for a couple pf days and some heat from below and hope for the best.

 

[Bill 1960]

What I do to try and remove rusted bolts, especially those with exposed threads beyond the nut, is a whole lot of back and forth. Once it initially breaks free with a breaker bar or what have you, I put an impact on it and start alternating CW / CCW only to the point of significant resistance. Plus liberal application of penetrating lube to creep into the newly cracked open threads and flush out the ground up rust particles.

Not 100%, but more reliable than just trying to keep going CCW after it initially breaks free.

I’m sure many readers and probably the OP know this already.