JD 450B helicoil stripped side frame to clutch housing holes

[Labparamour]

I measured my bolts and mine are 7/8" with no shoulder. The challenge
I ran into is the limiting factor of the 7/8 bore. When drilling out my broken bolt I had thought about a 3/8 drill chuck on an extension but the chuck had an OD over 1". I turned round stock to 7/8, bored one end 1/8" and the other 1/2." Welded 1/2" drill rod to the one end and had three set screws to hold the bit- then drilled fitting out to each bit size as I went up.
Taps require a bit of torque. Not sure if you could use female end of 1/2" socket extension to turn the tap (probably have to grind down the flats on the tap) or weld tap (and tap drill) to some drill rod without having them break when using. Was wondering if the exhaust of a shop-vac could be plugged into one of the other bolt holes to pressurize clutch housing and keep metal cuttings out…
Keep us posted.
DB
---just tried to upload photo to Flickr of a page from my tool catalogue unsuccessfully. However, my tool catalogue shows a 7/8"-9 extension tap with overall length of 6"('bout $100)… that might at least get you outside the frame to get a wrench or extension on it

image by labparamour, on Flickr
Got it!

[crawler123]

Labparamour I was thinking along some of the same lines as you.
Since I have both a broken bolt and a stripped hole I'll have to do both ;-(
One of the taps I ordered is 5.750 long and that should get me outside the side frame at least. The driving end square is 0.500 and should fit a 0.500 socket extension and then attach large tap handle.
And you are right the drill bit for the 7/8x9 tap is a 49/64" and will require some kind of extension. It's suppose to have 3 flats on the 1/2" reduced end and then the set screws.
These old tractors are such fun, aren't they !!!!!

[Lavoy]

Pack the tap with grease, that is one way to hold thread cuttings from falling where you don't want.
12 point sockets will work on a square shank, or you can buy 8pt sockets too.
Good luck.
Lavoy