Derailleur cable adjustment broke
 

While trying to remove the adjustment bolt, it sheared off in the thread. After much effort and time, I was able to drill out the most of the aluminum and I have three or so threads clear. Do I need to run a tap through to clear out the aluminum or is there another way?

Which one? H, L, B, cable fixing bolt, in line adjuster, barrel adjuster? Is this a front derailleur, a rear derailleur or something else? Help us help you.

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I believe it is called the inline barrel adjuster on the rear derailleur

No, it's just the barrel adjuster. 'Inline' barrel adjusters are located between 2 pieces of housing. I think your derailleur had a heli-coil in it from new. It's a little coil of steel that looks like a spring, it's supposed to give you a harder material than the aluminum the derailleur is made out of to screw the barrel adjuster into. You won't have any luck running a tap through that derailleur. Unless it means a great deal to you for some reason I'd toss it and move on. Time for a new derailleur.

I'd clean up the threads as best as you can so that another barrel adjuster will thread in & hope for the best.

Another option if the existing threads strip completely out or are drilled out, is to remove the plastic sleeve & spring & install a small nut on the replacement adjuster threads so that adjustability can be restored. The mechanic at your LBS likely has one rattling around the top of his tool box.

Or, do as above minus the small nut I mentioned & use an inline adjuster at some convenient place along the housing run. Up by the shifter is pretty common. Down by the frame headtube/toptube is subject to twisting forces with every steering correction & is less likely to stay well adjusted for long. (Ask me how I know.)

I see you have a Deore rear derailleur. Do you have a matching flat bar shifter? If it has a barrel adjuster, all others are reduntant, anyway. Screw the derailleur one all the way in & fugghedaboutit. :thumb:

I have three of the original threads free. The threads are not stripped, just filled with the remnants of the aluminum barrel adjuster. I can thread in a new adjuster, but only three threads worth until the old aluminum stops it from turning.

It sounds like you are looking for a tool called an "easy out" It threads into a hole you drilled into a screw or bolt and has reverse threads so that as it screws itself in the bolt, the bolt is forced into unscrewing from the hole.

Easy outs are available from almost any reputable hardware store & sometimes the home improvement type stores.

I tried an easy out but there was not enough bolt to grab. I was able to get most old bolt out, then I chased the threads with a stainless bolt and all is well. Thank you for your time folks.

Run tap through the hole. Make sure the tap is the same size, diameter and thread pitch, as the new adjuster you plan on using. You could also try removing the remains of the old adjuster with a pick. Either way, run a tap through to clean the threads.
Or drill the hole oversize and use a new adjuster with a nut.
Good Luck.

It sounds like base2's idea about a fixed RD termination of the adjuster is best.For security you might cut down the 3 thread stub, so it doesn't put any more strain on the adjuster than necessary.
You could dig out the old broken threaded part, but it would take a long time and make the drilling out more viable, as an option.
You are , as a surgeon friend once said to me, trying to sew snot together, so good luck.

I would resist the urge to run a tap through what’s left I would get a thread repair epoxy run in a new barrel adjuster with the thread repair compound. Follow this up with installing a new inline barrel adjuster, given the age of your derailleur you might even have one on the shifter.