Threaded Fasteners?

[Uglydog]

Am rebuilding a mechanical PTO on a 1970s Cub Cadet 149.
One of the 1/4x20 hex socket head set jam screws was stripped out.
In order to get it off the garden tractor I ended up drilling out the jam screw. And now need to rethread.

The PTO is an iron casting I need at least .750 of thread, 1 inch would be better. I've used helicoil, there are also other options such as Time-serts and Gard-serts. likely others as well. Because I'm cheap, I'm leaning drilling/tapping to the next size, using permanent thread locker on a grade 5 bolt and redrilling to 1/4x20.

Does anyone have a time tested opinion on best practice for a durable fix? These 3 set screws and their associated jams hold the pulley/sheave which drives any/all attachments and enjoys alot of torque.

Thanks,
Daryl
MN

[propforward]

I'm cheap, I'm leaning drilling/tapping to the next size, using permanent thread locker on a grade 5 bolt and redrilling to 1/4x20.

I've had good success with that kind of repair. Maybe go an additional size bigger if you have room - then you can also pin the insert in place. Overkill honestly - threadlocker red will not let go of the repair insert.

[TerryWerm]

If there is enough 'meat' available, I would follow your first idea and drill out to 1/4", then tap 5/16"-18.  I have done that more times than I can count.

The larger setscrew will hold better, and the larger hex key used will be less likely to strip out. Blue Loc-Tite should hold just fine and not require heat to get it to let loose later on.

If you are doing a complete 'new from factory' restoration you might consider a different approach, but the reality is that no one will see it as a rule. PTO implements on lawn tractors tend to create a fair bit of vibration and you would probably gain an overall benefit from larger setscrews.

Just my  worth.

I almost forgot: Welcome aboard Daryl! You will notice that I created one board in here specifically with you in mind!

[Uglydog]

created one board in here specifically with you in mind!

I saw the Foundry.

I'm working up to an Aluminum Bronze vs Red Brass question.

Daryl
MN

[34_40]

If it's just the jamming set screw you could always just change the fastener size for that screw.  No one will ever know..  done right the rebuilt PTO will last 30 plus years.