Thread: I'm stumped, need help

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I had a similar problem on my coupe, but with only two of the holes... The original thread is a 10-32. Get a fresh 10-32 tap and a series of small drill bits including a #21. Plan on sacrificing the tap; when you are finished it will not be good for anything else.

Start drilling with a bit that is too small and use oil. When you get a hole through all of the broken-off screws, move up to a slightly larger size. Keep going until you get to a #21 drill bit (.1590" dia.). By the time I got to this point, I had one insert that spun in the hole, so I had to stop and put a tiny tack weld on it.

Once you get them all drilled to the correct size, start tapping the threads. Obviously, the tap won't go deep enough to cut the threads all the way. Tap all the holes as far as you can. Then grind 1/16" off the end of the tap and run it down all the holes again as far as it will go. Keep repeating the process until you get good threads in all the holes. When you are finished, the tap will be devoid of its "self-starter" taper and therefore pretty much useless. Fortunately, 10-32 taps aren't very expensive. Good luck!

Originally Posted by J. Robinson

I had a similar problem on my coupe, but with only two of the holes... The original thread is a 10-32. Get a fresh 10-32 tap and a series of small drill bits including a #21. Plan on sacrificing the tap; when you are finished it will not be good for anything else.

Good luck!

Just a quick note - while these particular screws may be 10-24 (or 10-32, many of the OEM Model A machine screws are a kind of odd size for a hardware or big box store at 12-24 and with even a few 12-28's thrown in for giggles. McMaster-Carr have these as well as the taps and are relatively cheap too.