Exhaust tunnel crossmember captive nuts broken. Now what? Topic is solved

[slickdizzy]

Working on my ‘98 V70, I had to remove the downpipe due to a broken front oxygen sensor boss. Which of course means removing the small crossmember mounted under the exhaust tunnel near the downpipe to muffler flange (pic below for example).



This seemed straightforward enough (famous last words). The two bolts on the passenger side came out without drama. However, both bolts on the driver’s side made it out a few turns before the captive nuts inside the floor stamping failed and the bolts started spinning free.

I don’t know if I’d call it “lucky” but at least with the passenger side bolts fully removed, I barely had enough room to slide the downpipe over and out from the exhaust tunnel.

Now I have to figure out what to do with one side of this crossmember flapping in the wind on half loose bolts. My understanding is that this part provides structural stiffening (the C70 convertible brace attaches in the rear where this plate is) so I definitely want to find a way to get this reattached.

I can cut the heads off of the existing, free spinning bolts easily enough, but then I still have two captive nuts bouncing around in there to deal with; and looking at the floor pan stamping, it does not appear these can be accessed from inside the car, it looks like they are sandwiched between layers of metal...I can’t see any way that I could extract the broken captive nuts without really hacking up the underbody stamping.

Has anyone dealt with this before that has any suggestions?

[Chuck W]

I had one break loose on my '97.

I cut the bolt and was able to work the captive nut out through one of the open holes on the body. The one towards the other end of the body panel has a large enough hole to fish them out.

I bought a riv-nut tool and installed a new threaded insert.

[slickdizzy]

Great suggestion! I didn’t realize there were larger holes near the captive nuts, must have overlooked them in my frustration.

Did you use riv-nuts that replicated the original metric bolt thread, or just the closest thing that fit? Any idea what the originals were (M8 standard pitch)? I’ll buy a tool just to do the job if I have to, but would like to borrow one and just buy the necessary inserts to save some $$$ if possible.

[Chuck W]

They are M8x1.25 thread. I used appropriate metric inserts.

That kit I bought from Amazon was under $50, and came with a bunch of inserts. I'll find many uses for it in the future, so adding a new tool to the inventory was a no-brainer.

[Cookeh]

Im a huge rivnut fan, incredibly useful items. If you're looking for further areas to use them in, to justify purchasing the kit, using them in combination with button head screws is a far far superior option for securing mudguards and arch liners. It also allows for easy access in the future for maintenance purposes. That will use up about 20 of them...!