How to fix a stripped nut

[8man]

I am working on a 48 Chevy pickup and 2 of the four bolts holding the hood to the hinges have stripped the nut built into the hood. The nut is built into the hood support and I can't get to the back side, and it will be a real pain to get the supports off to work on the back side.

The hood bolts are 5/16" -20 with a shoulder that the hinge rotates on. That shoulder makes a tight fit so it doesn't move around. The PO drilled out one to a 3/8" - 16 and put a plain bolt in the hole. That bolt allows the hinge to move around and won't allow me to set the hood properly.

I've been told nutserts or rivnuts, but I don't have the room on the back side of the support for that.

Is there something else that might work? I can drill it out and tap it if there is something else.

I would appreciate any help on how to fix the nut.

 

[lilredex]

What is the diameter of the shoulder that the hinge rides on?

 

[Moosefire]

Theres weldnuts, but usually that's done before assembly by a spot welding machine... what about friction drilling?

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[readhead]

Weld up the nut, drill and tap it.

 

[59 wagon man]

pic would help

 

[ItsNemo]

Weld up the nut, drill and tap it.

This.

 

[TruckRed]

Drill out the nut for 5/16-20 helical thread insert and install. Use a helical insert of the correct length.

 

[CJM8515]

could always do a nutsert too.



me id weld the nut and drill and retap it.

 

[DFB]

Can you get the original hinge bolts with the shoulder?

Sounds like Helicoil type insert is what you need to do if welding isn't an option.

 

[kerrynzl]

Helicoils? or threaded inserts

 

[Maddog3355]

I’ve never been able to drill and tap a weld. If you guys say it works I must of always had bad drill bits.

 

[8man]

Helicoil? I'll research that and see if it will work.

Thanks.

 

[John T]

Helicoil? I'll research that and see if it will work.

Thanks.

That would be my vote also.

The kit comes with a drill bit/tap and tool to insert the coil.

Just go slow and easy drilling out the nuts. They are usually tack welded on the back side....

If the nut breaks loose, now you're in for heartache...

 

[Dutch01]

Have the same problem as the OP on my 1964 Austen Healey Sprite. Do not know whether helicoils would do the job as the thickness of the nut may not be sufficient for grip. My consideration is also to use rivnuts or alternatively drill the hole bigger and press fit and weld/braze a pre-threaded nut in position similar to this that I have done on an engine mount.



Obviously the hexagon section would be machined much thinner.

I would like to hear how the OP overcame the problem.

 

[joe_padavano]

There are a variety of thread repair systems. Helicoil is only one. Keenserts are solid, not a wire coil, and will work with less thread engagement. Timeserts are another. I wouldn't mess with welding or other half-fast solutions. Just use a tread repair insert. McMaster Carr is one source for a variety of thread repair inserts.

 

[Muggzy]

Not sure how thick the surrounding metal is that you're dealing with. When the footpeg bolt hole failed on my 4-wheeler, I filed out the surrounding material and pressed the hex side of a flanged nut with the correct M10-1.5 thread into the enlarged hole. With the the flange providing some material (and margin for error) to weld, I welded around the flange to the frame. It only moved the surface out about 1mm and the new threads were perfectly fine as is.
If you want, I can post some step be step pics of the process. Worked great and I used to jump that 4-wheeler some pretty good heights. Never broke again.

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[Monza Harry]

I am working on a 48 Chevy pickup and 2 of the four bolts holding the hood to the hinges have stripped the nut built into the hood. The nut is built into the hood support and I can't get to the back side, and it will be a real pain to get the supports off to work on the back side.

The hood bolts are 5/16" -20 with a shoulder that the hinge rotates on. That shoulder makes a tight fit so it doesn't move around. The PO drilled out one to a 3/8" - 16 and put a plain bolt in the hole. That bolt allows the hinge to move around and won't allow me to set the hood properly.

I've been told nutserts or rivnuts, but I don't have the room on the back side of the support for that.

Is there something else that might work? I can drill it out and tap it if there is something else.

I would appreciate any help on how to fix the nut.

Are you sure about that thread? 5/16-18 and 5/16-24 are normal UN threads 5/16-20 will be harder to find, M8-125 is very close but I doubt that is stock on a 48 Chevy. I'd recheck that pitch before you go looking for unobtanium. Harry

 

[bubinga]

I’ve never been able to drill and tap a weld. If you guys say it works I must of always had bad drill bits.

My experience even grinding weld it is very hard material. Never tried to weld and drill it but grinding it man that stuff was hard.

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[bad_idea]

My experience even grinding weld it is very hard material. Never tried to weld and drill it but grinding it man that stuff was hard.

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I've done it fairly often. I work in ship repair. It is not uncommon for some jack *** to drill the holes in the wrong spot. Common practice is to plug weld the holes and drill the new hole in the right spot. Now you are drilling through part of a weld. With the correct drill bit, good cutting paste, correct rpm and good feed rate it isn't too bad.

 

[bubinga]

I've done it fairly often. I work in ship repair. It is not uncommon for some jack *** to drill the holes in the wrong spot. Common practice is to plug weld the holes and drill the new hole in the right spot. Now you are drilling through part of a weld. With the correct drill bit, good cutting paste, correct rpm and good feed rate it isn't too bad.

OK, Sounds good, thanks!