Re-boring and tapping bolt holes for mid PTO assembly?

[Lil Foot]

https://www.napaonline.com/en/search?text=helicoil%20kit&referer=v2

I have probably installed 10s of thousands (more?) of helicoils, keenserts, timeserts, rosan inserts, (and others) in production settings, toolmaking shops, and repair scenarios.
I would not even give thought to anything except helicoils for this sort of repair, they are certainly the most forgiving on installs, the most widely used and available. I probably have 40 different kits, in US and metric, plus a fair amount of other brands/styles.
If you cannot find the length you need, simply buy longer and cut to length with a dremel cutoff wheel.
Another advantage of helicoils. (be sure to cut off the correct end)
The single biggest problem with inexperienced installers is oversize or wallowed out holes. Work your way up from smaller sizes to the tap drill size, keep it straight and don't wallow out the top end of the whole, and your repair should be stronger than the original thread.

 

[rustythread]

Appreciate all the responses.

I've ordered some M8 x 1.25 x 2.5D (20 mm) coil inserts and a drill + tap + insert tool kit.

Annoying how many of the "complete kit" sellers won't list the depth of their coils. Spent several shining hours searching for the right coils in a package of less than 100. Got order on file, and confirmation promises delivery by mid-December if'n the cricks don't rise.

MUCH ADO ABOUT NOTHING

Got the insert tool kit in, then the longer inserts. Made a fixture to which I attached the mid pto case, and bolted to my drill press table with the stripped-out bolt hole properly aligned with the drill chuck. Got out the tape and a depth gauge to set up the drilling and tapping depths for the inserts. What the..? Waitaminute!
The original tap bolt length was 20 mm--about 17mm net with the lock washer. The clearance through the cover took up about 10mm: i.e., there was only about 7-8 mm of threaded bolt length in the hole and therefore only about 8 mm of the depth stripped out. BUT the depth gauge showed 30mm+ of hole, and a bunch of craning my neck and playing with the light showed that the bottom 10mm+ of the hole still has good threads. I put in a 30mm long bolt with a lock washer and it snugs up just fine. At least as much as originally. Looks like the design engineer sprc'd a 30mm bolt, and the bean counter ordered the 20mm to save a yen.
Feelig pretty dumb here. Another lesson learned, and the tuition wasn't all that high.

 

[TheOldHokie]

MUCH ADO ABOUT NOTHING

Got the insert tool kit in, then the longer inserts. Made a fixture to which I attached the mid pto case, and bolted to my drill press table with the stripped-out bolt hole properly aligned with the drill chuck. Got out the tape and a depth gauge to set up the drilling and tapping depths for the inserts. What the..? Waitaminute!
The original tap bolt length was 20 mm--about 17mm net with the lock washer. The clearance through the cover took up about 10mm: i.e., there was only about 7-8 mm of threaded bolt length in the hole and therefore only about 8 mm of the depth stripped out. BUT the depth gauge showed 30mm+ of hole, and a bunch of craning my neck and playing with the light showed that the bottom 10mm+ of the hole still has good threads. I put in a 30mm long bolt with a lock washer and it snugs up just fine. At least as much as originally. Looks like the design engineer sprc'd a 30mm bolt, and the bean counter ordered the 20mm to save a yen.
Feelig pretty dumb here. Another lesson learned, and the tuition wasn't all that high.

I am going to bet this won't be the last time you visit this problem.

Dan

 

[rustythread]

I am going to bet this won't be the last time you visit this problem.

Dan

Maybe. But if so, I'll have all the tools and supplies on hand.