2001 Toyota RAV4: Broken captive frame nut repair
We were taking H to preschool last week in our trusty RAV4. I turned left off our street and we both heard and felt a troubling clunk. When we got to her school, I peeked under the car on the driver’s side. Clear as day there was a bolt hanging loose. It was one of the bolts holding on the subframe crossmember. Yikes. It could only mean one thing: a captive (i.e. welded) nut inside the frame of our car had broken loose. Double yikes.
K and I were both quickly resigned to the reality Luna (what we named our little RAV) may be a goner. I can do a lot of things to a car, but welding is not one of them. We started looking around at used RAV4s and 4Runners. At the same time, not wanting to seal Luna’s fate that easily, I called around to some shops in town to see if they could cut into the frame and re-weld another captive nut inside. I got a bunch of "Nope, we don't do that."
That is, until a guy from one of the shops called me back a few days later. I had sent him over a few photos of the bolt along with one where I had peeled back the carpet and insulation under the pedals inside the car. That was where I had estimated I could gain access to the bolt from above without having to cut into the frame. He asked me if I’d ever need to remove that nut again, which was essentially asking if I’d ever have to remove the crossmember. I sure hoped not, I replied. Then came the Aha! moment: if I wouldn’t need to loosen that bolt, he pointed out I didn’t need to weld it.
Translation: all I needed to do was get the bolt and nut out of there and replace it. No welding necessary. I thanked him and said sheepishly I hoped we wouldn’t speak again, at least not about this particular issue. Then I got to work.
Step 1: Do my darnedest to determine where exactly the bolt was under the sloping floorboard to minimize the drilling I’d have to do into the floor
Step 2: Once confident I had that figured out, I broke out a hole saw and drilled––first through the floor, then through two more layers of sheet metal (it was no problem and nothing structural)
Step 3: I had to break the rusted nut free (spoiler: it wasn’t going to break loose, not with various breaker bars and not with an impact wrench sporting 500 ft-lbs of breakaway torque)
Step 4: Between a cutoff tool and ultimately a good ol’ fashioned grinder I ended up cutting off the bolt (thankfully, oh so thankfully, the visibly loose bolt had a couple of millimeters of give for me to get a blade into it)
Now we were getting somewhere. With the bolt and captive nut removed, I had to source replacements. A call to the local Toyota dealer scored me an $8 bolt (Toyota part 90119-A0014) and, after an unsuccessful trip to Fastenal, a quick search online yielded the matching $4 M14 1.50-pitch flange nut (Dorman part 611-295.1) from AutoZone. Worth noting: both the bolt and nut are Grade 8; not just an ordinary bolt and nut.
Step 5: Install the bolt and nut, then torque to spec (116 ft-lbs)
Without having to weld, installing them was straightforward. I broke out a few tricks:
- To hold the bolt upside down through the frame before threading on the nut, I duct taped it to the subframe and put a floor jack up against it
- To hold the nut on the socket as I lowered it into the frame on a wobble socket extension through the holes I drilled in the floor, I taped it to the socket
- To hold the nut in place while I torqued the bolt to 116 ft-lbs, I wedged a breaker bar against the center console flooring
