So, I am going to revise my previous statement. I believe there ARE inserts in these wheels. This pic is from my bolt removal efforts last night...
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Yes, I fucked it up, trying to drill it freehand. I should know better by now, but I still seem to learn the hard way. Anyway, if you look close at the upper edge of the hole, you can see another edge, like of an insert. I'm sure of it.
Like I said, they are D-I-R-T-Y and its easy to mistake the little top flange of a timesert for a chamfer...
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I still have a whole other set of holes I can use, so this wheel will be fine, regardless if I'm able to get another insert in there, but I'm planning a drill fixture that will bolt into the holes to either side of the damaged hole, that will have a drill guide for a 21/64" drill bit. Then I will tap with a 5/16" SPI tap and install a new insert. Hopefully the 21/64 bit cleans everything up. The endmill I used was just under 5/16 (it was a regrind) so I should still have some meat to remove. I don't know that I'll get that whole little wobble out that is show in the zoomed in picture, but we'll see. Maybe an E-Z-lock style insert will fit. I believe those work on the next size larger thread (so a 3/8 outer thread for a 5/16" repair).