[AT] Drill size for bolt tap question

[rlgoss at twc.com]

If I remember correctly, those drill/tap size recommendations are so you retain 75% overlap in the thread engagement.  It should work, but will be a loose fit during assembly.  It will easily be stipped out again, so use caution.

Larry

---- Al Jones <farmallsupera1 at gmail.com> wrote: 
> I've got some wallered out holes on a Farmall Super A torque tube that I
> want to fix.  They need to be 5/8" coarse thread, but somebody stripped 'em
> out, then did some sort of funky drilling, and now my holes are 15/16" in
> diameter.  I'd like to fix it myself but the longer I look at it the more I
> fear a machine shop visit is in order.
> 
> My notion is to try to tap the holes for a threaded insert.  If I drill the
> holes out any larger for a larger tap, it's going to eat away the square
> boss on the side of the torque tube, so I want to avoid that. Now, the
> chart I am looking at says you need a 7/8" hole for a 1" tap. That means
> the existing holes are 1/16" too big.  Can I still tap it with the 1" tap,
> Loctite the daylights out of the insert, and get it to hold? These holes
> are on the left side, and there weren't many implements that used these
> holes, plus it's going to be mainly a show/plow day tractor.  But I do want
> them functional and they have to "look good."
> 
> I have a good torque tube, but this is an early (probably built the first
> or second day of 1950 production) white demonstrator tractor, so I'm trying
> to keep the castings original.
> 
> thanks!
> Al