Stripped Weld Nut for Mounting Hitch on '04 Impreza WRX

[LaszloT]

I put a Curt class I hitch on my WRX for a bike rack.

Unfortunately the existing machine thread fasteners were tired and we stripped the threads in one weld nut, which is not good.

The Curt hitch has but 2 fasteners on each side so I want to repair it, but there's no access to the interior of the frame rail so what corrective options exist?

1. drill/tap larger size
2. Helicoil new threads
3. pull bumper off to put a new nut into the interior of the frame rails?

[JoeT]

Not that difficult, as a matter of fact it's a 10 minute fix.

1) Go buy a grade 8 or better bolt somewhere that's slightly thicker than your existing bolt.
2) Use a Tap and Die set to cut new threads that match your new bolt. Don't worry, your welded nut has enough meat to take care of the new thread being cut.
3) Use lots of lube when cutting new threads and clean often (back off and respray with lube
4) Thread in your new bolt and use Anti Seize, and you're good to go.

See.. simple eh.

[LaszloT]

Awesome! Thanks JoeT. :)

[LaszloT]

Is 1/2 inch tap sufficiently larger than a M12 then?

[wparsons]

I've got a full tap set if you need it Laz.

[LaszloT]

Yes please, Will. May I pick it up from you at lunch this week, and return it to you next Mon?

Caveman suggests a 1/2 inch tap.

[7plymaple]

Yes please, Will. May I pick it up from you at lunch this week, and return it to you next Mon?

Caveman suggests a 1/2 inch tap.

12mm = 0.472" Going up to half inch only gives you .014" of thread engagement. Not enough IMO. There might be a little more engagement than that but looks like that bolt chewed the old threads out of the nut. So it's inside diameter is probably pretty close to 12mm. And bolts are always a little under in diameter when you measure them on the threads.

For nice clean new threads Go up to a 9/16 (.5625") tap and drill with 31/64 drill. I think there should be enough meat in the nut for that.

[wparsons]

Yes please, Will. May I pick it up from you at lunch this week, and return it to you next Mon?

Caveman suggests a 1/2 inch tap.

Yep, I'll bring it Thursday. I'll probably be working from home Wednesday. No rush to get it back.