Need help with a mistake I made removing broken bolt studs

[skrit]

I have a build thread here: https://classicbroncos.com/forums/threads/build-thread-1974-horse-with-no-name.322617/

I was hoping someone could chime in on how best to fix my screwup from my attempted broken bolt removal shown as "Concern #3" at the bottom of the post here: https://classicbroncos.com/forums/threads/build-thread-1974-horse-with-no-name.322617/post-3538611

Many thanks in advance!
Here is a preview:

 

[widowmaker77]

Maybe heli- coil it?

 

[RM70]

Depending on how well you wanted it done I could think of a couple options.

1. JB Weld the holes, drill and tap.
2. Helicoil
3. Drill them out and tap for a larger bolt
4. Have the holes welded up, drill and tap.

 

[Wild horse 75]

I agree with using a Helicoil. If you can drill it from the backside with the larger bit for the Helicoil that way you are going to be centred better. Also if you go up in small increments with the drill size you are less likely to go sideways.

 

[Oldtimer]

They are thru holes.
Can you open them up to full diameter of bolts, get longer bolts and place a washer and nut on the far side?

My next option would be take it and the tail housing to a machine shop,
have them map the hole locations in tail housing,
transfer locations to transmision housing,
bore oversize holes in correct location,
and install keenserts.

 

[jamesroney]

The first thing that you have to do is finish the job that you already fouled up.

You have to get rid of all of the rest of the old bolt. You can see the little quarter moon shaped hunk of steel remaining in the hole. Take a center punch, and see if you can wedge out that little piece. Every solution that is going to be posted will in some way require you to have a clean, round hole in the parent metal. You are still in great shape, and it is very salvageable.

If you can knock out the chunk of bolt threads, then you have a chance of drilling it oversize by hand. heli-coil, keen-sert, re-thread, and "next size up" all require a good hole.

Once you have a clean, round hole...I'd tap it oversize, and use a bigger bolt. But the bolt and nut solution is also attractive.

 

[knack]

X2 on the machine shop. Easily done there.

 

[skrit]

Thanks for all that replied. I'll update my build thread post with what I'm planning to do.