Type of tap to repair threads

[logang1k]

What type of tap do i need to fix some m12 x 1.25 threads I gulled up? I can see good threads but the first 1/4" or so of threads are messed up pretty badly. It's a rear subframe to body bolt hole.

Edited May 25, 2010 by logang1k

[logang1k]

In my area it might be easier to drill it and tap it to fit a 1/2" bolt. I have a 1/2" tap. Should I use fine or coarse?

[Twitch de la Brat]

To answer your first question, you can clean up threads with a slightly different

tap, as long as they are just starting threads and not the whole thing.

Such as you can use a 12x1.5 tap to clean up some 12x1.25 threads.

 

And if you wish to get just a straight 12x1.25 tap, good luck.

I've tried to find one for myself, and they are next to impossible to get.

 

As for your second question, if you are going to drill it to 1/2 in and re-tap, use

a fine threaded tap.

12x1.25 is considered extra fine, so a fine thread standard should be ok.

 

Twitch

[monstaru]

how impossible is it to go to an ace hardware?that is where i got my 12x1.25 tap....

just go buy a tap......geezus

[GeneralDisorder]

That's a common size.

 

www.mcmaster.com

 

Part number:26015A232

 

I would not be drilling and tapping a body capture nut. They are only spot welded in place. You risk potentially breaking the bond between the body and the nut. If that happens you will be cutting out that section of the frame, welding in a new section and installing a riv-nut, etc.

 

GD

Edited May 25, 2010 by GeneralDisorder

[monstaru]

depending on the bolt, you can drill through from the top, put a socket on it and tap away.........

 

but technically , he is right...bad idear.however, when i did not know better, i did this several times without drilling a hole (with a hole saw)above, and was able to clean them out pretty well.......

 

cheers, brian

[logang1k]

yeah I took a small hole saw (1-1/4) to the panel above the offending bolt hole. I thought I could run the bolt through it backwards but I couldnt get it to start. Im thinking about drilling it out very slightly and running a bolt straight though and using a nut on the bottom or top. anyone opposed? The threads are pretty f'ed.

[GeneralDisorder]

You could through-bolt it like that - but if it's me - I'm pulling out the welder about now. Capture nuts are screwy enough and already prone to failure without a lot of modification. Since you already have a hole in the floor (), weld that sucker down tight (adding more material in the process) and then tap it oversized.

 

GD

[baccaruda]

why not remove & replace the capture nut with a new one with the proper threads? just put a socket on the bad one and twist it off with a breaker bar.. maybe drill or dremel the welds a little to weaken the bond. Good luck.

[obk25xt]

All the holes on my lift were drilled and tapped to 1/2", And I have have no problems to report with 20,000+ miles and some serious wheeling as well. Mind you now, my car is completely subframed and this may have something to do with the rigidity of the entire car...