Front control arm bolt spinning

[E34_Guy]

Rusty Subframe Captive nuts

I didn't plan for this to be my first post, but there's not enough info out there on this topic.

If you're living in 2022 and you have an NCP91/XP90 or 2nd Gen Yaris in North America where we have snow and salt, This is definitely something you should be concerned about.

This is the second time I'm dealing with this issue. The first time, I was trying to unbolt the control arm to pull out the driveshaft to change the output shaft seal on the transmission. Needless to say, I never got to changing that seal as this new problem arose.

The front control arm bolt that runs longitudinally is secured by a "captive" nut that is buried INSIDE the front subframe/crossmember. Meaning that if the bolt is rusty at the tip, it may start coming out without any issue, but as soon as the threads start reaching the end of the bolt where it may be rusty, friction on the nut increases and you run the risk of completely destroying the small metal cage that holds these nuts in.

So you're probably here because your bolt is spinning and not coming out and you want to know how to fix this seemingly impossible problem.

Tools needed:
Mig Welder or Stick Welder (I use a Lincoln Electric mig 250)
Sturdy Vice Grips
Angle Grinder with healthy wheel
Steady hands, and some patience

First up you want to cut into the subframe and make an access panel to get to the rusty carnage that lies beneath.


Use the vice grips to pull/peel the metal back giving you access to the nut.


This ended up not being enough access to the nut, and I had to cut even further into the subframe


Once you're able to get some good access to the nut, you'll be able to see the cage that's supposed to keep this square nut captive.

In my case, it was completely mangled and fell out.


OK now that you can see and have some access to the nut, It's time to pull out your welder. This part is exceptionally difficult because you have to weld directly upwards against gravity, and you want to make sure you get the wire all the way up in the hole and not stuck on the sides of your new access panel. I would recommend starting by making contact with the captive nut first and trying to get the flow onto the inside of the subframe as gravity pulls it down.

Here are my crude welds


Once you have a secure weld on the nut, you should be able to carefully crank out the bolt. Just be aware of the secureness of your welds as you crank on it as you don't want to break them.

Now you can continue doing whatever it is you set out to do.

For me it was replacing the control arm.



I hope this post has been helpful and keeps someone from completely scrapping their car. That being said, If you do have this issue, I would strongly recommend looking into a new subframe lol.