Holding a broken captive nut

[JHZR2]

On my 1991 mb 350sd I can tell the guide rod mount is loose. So I’m going to replace it, the bushings, and the lower control arm bushing.

Everything went well until the captive nut on one of the main bushings broke. There is very little corrosion but apparently enough on this bolt to cause an issue.

This is what happened:

This is what it should look like, this was the second bolt, same mount, not three inches away.

The access on either side is not sufficient to get a wrench in there. The larger hole is on the inside, blocked by an idler arm, steering shock, transmission bellhousing, etc.

The access from the outside is this:

It’s about enough space to fit a 5/8” spade bit into. Maybe a bit more.

What is my best bet? I’m thinking to drill into the nut, then beat a punch into it and use that to hood the nut. But the punch will be tiny and I’m not sure if it will just bend.

I was also thinking long skinny end of an air hammer, but I don’t know if I’ll have the length or access.

Any recommendations?

Thanks!!

 

[spasm3]

I have a super thin wrench set, would this fit ?

 

[JHZR2]

View attachment 160579View attachment 160580I have a super thin wrench set. would that fit?

Nope. The holes aren’t wide enough to fit a wrench that would keep the 22mm flats in place. It’s a width issue not a height one.

 

[spasm3]

Nope. The holes aren’t wide enough to fit a wrench that would keep the 22mm flats in place. It’s a width issue not a height one.

Sorry its hard for my eyes to scale .

Since it is a square nut, could you make your own 22mm open end wrench from a piece of flat stock ? Is the opening wid enough for that ?

 

[JHZR2]

Sorry its hard for my eyes to scale .

Since it is a square nut, could you make your own 22mm open end wrench from a piece of flat stock ? Is the opening wid enough for that ?

That’s a good idea! Even if the flat stock isn’t very thick… but I should be able to get in a piece that’s as thick as the 5/8” spade bit I was trying to use. I like it!

Drill the four corners then cut the flats with a small Dremel cutting wheel? Or a hacksaw?

 

[IndyIan]

If it’s not really stressed, maybe just put a rectangle piece of 1/4” mild steel big enough not to spin with a threaded hole tapped in it?

 

[spasm3]

That’s a good idea! Even if the flat stock isn’t very thick… but I should be able to get in a piece that’s as thick as the 5/8” spade bit I was trying to use. I like it!

Drill the four corners then cut the flats with a small Dremel cutting wheel? Or a hacksaw?

Thin cut-off wheel on a grinder. A 1/4 inch angle grinder with an arbor and 3 inch cut off wheel.

 

[joegreen]

How about welding the nut back on. I’m sure any shop would throw a couple tacks on there for a few bucks.

 

[JHZR2]

If it’s not really stressed, maybe just put a rectangle piece of 1/4” mild steel big enough not to spin with a threaded hole tapped in it?

The whole thing needs to come out/off. I’m replacing bushings. The bolt just spins now because I can’t get the nut off.

How about welding the nut back on. I’m sure any shop would throw a couple tacks on there for a few bucks.

Doubt there’s access. The opening on the wheel well side is maybe 1/4” x 3/4”. The opening on the inside is slightly bigger but totally blocked.

 

[JHZR2]

So, so I think I’m going to try to drill into the nut. Then I can either hold it with a little punch, or relieve stress, or drill through the nut and bolt (I’d prefer to keep the bolt in tact and reuse).

It’s going to need to be a very small, long drill bit. I’m sure it will want to walk. Not sure how I can get a punch in there to make a dimple. Maybe a scratch awl, but not sure it will be hard enough…

What’s the best bet for getting the drill bit to start into this nut?

IfI ultimately need to destroy the nut, how do I split it given limited space. Some sort of tiny cold chisel or something?

 

[DuckRyder]

I woul try to reform the holder, particularly the edges that roll over the edges of the square nut and then try to hold it in place with a pry bar while trying to listen the bolt by hand.

 

[spasm3]

Another idea, can you get a long sawzall metal cutting blade in that slot and cut the bolt, or saw under the nut? With a ratchet on the bottom , it should not spin as you saw.

Then buy an new bolt.

 

[JHZR2]

Another idea, can you get a long sawzall metal cutting blade in that slot and cut the bolt, or saw under the nut? With a ratchet on the bottom , it should not spin as you saw.

Then buy a new bolt.

That’s a worst case option but it would need to be more like a jigsaw in dimmension.

 

[JHZR2]

I woul try to reform the holder, particularly the edges that roll over the edges of the square nut and then try to hold it in place with a pry bar while trying to listen the bolt by hand.

The rolled edges I think just keep the width down. They don’t hold the nut in there. Maybe I can enlarge the hole in the holder to be 22x22mm and just slide it over….

 

[Trav]

I may be a bit dim but I don't get this, you have the piece in your hand missing a square nut. Why cant you straighten it out and tack weld a square nut to it?

 

[spasm3]

I may be a bit dim but I don't get this, you have the piece in your hand missing a square nut. Why cant you straighten it out and tack weld a square nut to it?

The nut is on the bolt, the plate came off, the nut spins when the bolt is turned from the bottom. He only has a small slot to try and get the 22mm square bolt held to unbolt it. A wrench won't fit width wise.

I suggested he make one from flat stock, or cut it with a sawzall blade.

 

[TheLawnRanger]

The best way to hold a broken captive nut is with a straight jacket.

 

[JHZR2]

I may be a bit dim but I don't get this, you have the piece in your hand missing a square nut. Why cant you straighten it out and tack weld a square nut to it?

As @spasm3 said, the retaining piece is not attached, and the nut is still on the bolt. Spinning, loose, in that tiny bit of the body that I can’t access with a normal tool. It’s like a 1/4” by 3/4” opening.

Plus I don’t have a welder. Couldn’t access if I did. Need to drill or cut the nut out instead somehow.

 

[paulo57509]

Possible to cut the bolt off close to the bracket and thread the shank and the nut out the back? This should open up options to get it back together.

 

[JHZR2]

Possible to cut the bolt off close to the bracket and thread the shank and the nut out the back? This should open up options to get it back together.

That is possible. The bolts are available after all these years.

But I’d rather reuse the bolt. I doubt there’s anything wrong with it. It’s just because the nut wasn’t held on well to the captive metal.