Rusted bolt from caged nut removal | How to Paint Your Own Car, Auto Body Discussion Forum and Videos

Rusted bolt from caged nut removal

Author: Brian Martin


Removing rusted tight bolts and old cars go hand in hand. There is nothing that connects you and the guy three states away working in this garage more than rusted bolts, he has them, you have them and every other guy or gal who has ever worked on old car has had them, you are a member of a club. Tonight while removing the front fenders on my Rambler it hit me that a lot of guys would be breaking these bolts off and causing a lot of work for themselves. I figured a “basics” was in order.

There are many different methods to get out rusted bolts. These methods depend a lot on exactly where this bolt is rusted. But this one in particular is helpful just about anywhere. With a caged bolt where you can’t get to the back side to lube it, this method works like magic.

A lot of body bolts on cars have a “caged” nut on the backside. This nut is as the name implies being held by a little “cage”. The nut is usually floating around in that little cage allowing a little movement for alignment of the part or body panel. When you have a caged nut inside of rocker like in my case tonight it can be a nightmare.

The bolt in photo #1 is just one of these bolts, it is holding the bottom of the fender and going up thru the rocker to a caged nut inside. The moment I started turning I knew I had to take every precaution possible or end up with a mess.

rusted bolt

The bolt is jammed by rust in nut and the minute you spin it the nut breaks the cage and you are stuck with a nut spinning inside with no way to grab it. Photo #2 If you just spin this bolt out the rust is going to get all jammed in the threads. Even a bolt that first turns freely will quickly become jammed up and locked tight ready to break with the next twist of the ratchet.

rusted bolt

1. Don’t try to muscle the bolt out!

If the bolt is stuck in rust, getting bigger tool is likely going to just give you more leverage to bust the cage or bolt. This is one part of the method that came when I first started tapping holes for threads. When you tap a hole with a die you don’t just spin the die in like a bolt, you go back and forth. You turn it in a little, then reverse it out a little, then in a little, then put a little cutting oil, then turn it in a little cutting a few more threads then out, then in cutting the threads a little deeper. This is continued until the whole is threaded through.

Use the same method when removing a rusted bolt like this, the rust will flake off and not get jammed up in the threads. Turn it out until there is some resistance and change direction and tighten it back up, then loosen it again going a little further out, just a quarter turn more, then go back up in side, then back it out going just a tad more again. Each time you unscrew it a little more you are “cutting new threads” on the bolt. So instead of the rust getting all jammed up in the threads it is falling off a little at a time. Just go a little at a time. Photo #3

rusted bolt

2. Lube it!

Now, how can you lube it you ask? The nut and top of the bolt is up in the rocker and you can’t get to it. Well, once you get the bolt out a little you spray some lube on the bolt, so now when you turn it back in you are pushing lube up into the threads! After you have turned it out and back in a few times, lube it again. Photo #4 shows just how little you can have it unscrewed and still get some lube in there.

rusted bolt

In photo #5 you can see that it has screwed out quite a bit more. It was still VERY tight and hard to turn, but going back up and then down, adding more lube and then back up to bring that lube up into the threads it would let me turn it that little more out each time.

rusted bolt

This isn’t a big drawn out deal. Just a couple more minutes will save you a bunch of time in the end!

Photo #6, Notice how this bolt that was installed over 50 years ago has unscrewed out of it’s caged nut without incident. You can see the rust piled all over the bolt, if I had just muscled it out I would be out there right now drilling out the broken bolt or cutting a hole in the rocker to replace the nut!

rusted bolt

Like with all things you do on an old car, a little patience will get you a long way.