How to repair stripped welded in frame and chassis nuts - professionally

[dave6666]

I know, you can always drill them out and put a bolt through those pesky nuts they weld to the chassis when you strip one. Or get a nut on the back side if you have access. I always try to get as close to OE as possible, throwing in any engineering I can along the way.

Well, my rear exhaust hanger stripped out a thread, and here we go.

Stripped this one:

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No threads here:

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The fix will be to drill it out and install a weld nut from McMaster Carr.

They have several sizes & styles, but this is what I used:

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They are advertised as 3/8" OD for the 5/16-18 thread, but they were actually about a 64th over at the base.

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Top - 3/8"

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Base - 1/64th over

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So I drilled out the stripped nut to 3/8 plus 1/64, and gave it a chamfer with a countersink to allow for the radius at the base of the weld nut flange.

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Tapped in the weld nut:

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Get a good ground:

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And weld:

BTW, I did disconnect the PCM and battery when welding. Your call on that.

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Touch up with your favorite chassis paint and you are done.

 

[ViperTony]

As always, great how to Dave. This needs to go into the illustrated's section. I stripped one of those holes and ended up using a heli-coil which has held up well. But yours is a much better and permanent fix. Thanks - Tony

 

[Y2K5SRT]

As always, great how to Dave. This needs to go into the illustrated's section.

Agreed and done!

 

[1TONY1]

Nice post.

 

[FATHERFORD]

As always, great how to Dave. This needs to go into the illustrated's section. I stripped one of those holes and ended up using a heli-coil which has held up well. But yours is a much better and permanent fix. Thanks - Tony

Nothing wrong with a heli coil. It's a quick easy fix that works just as good as regular threads, if not better.

Dave's way looks more beautiful though.

 

[dave6666]

Nothing wrong with a heli coil. It's a quick easy fix that works just as good as regular threads, if not better.

Dave's way looks more beautiful though.

A couple of reasons I did not do a heli coil:

-> Broken taps ****. If that happens.

-> Crooked threads ****. If that happens. There was no margin for crooked threads here, as screw had to go straight.

-> Could not tell what would have been the remaining wall thickness of the drilled and tapped OE chassis nut when prepping for the heli coil.

 

[FATHERFORD]

A couple of reasons I did not do a heli coil:

-> Broken taps ****. If that happens.

-> Crooked threads ****. If that happens. There was no margin for crooked threads here, as screw had to go straight.

-> Could not tell what would have been the remaining wall thickness of the drilled and tapped OE chassis nut when prepping for the heli coil.

Well I understand that, but for some reason if people hear "heli coil" they freak out and think the item is garbage. If it heli coil's are done right there shouln't be any problems.

Either way, the way you did your's is much slicker.

 

[Kenneth Krieger]

Great how to feature.......good work and thanks.