What Can I Do About Stripped ATV Diff Fill Plug?

If the threads on an ATV differential fill plug are stripped out past the point of being able to extract the bolt with thread repair tools, what else can you do?

Partzilla’s ATV expert John Talley hosts live Q&A sessions on our YouTube channel every Friday at 3pm Eastern. In this session, John was asked what could be done about stripped ATV differential fill plug threads when there’s also a crack above the bolt.

Stripped ATV fill plug

Stripped ATV Diff Fill Plug Threads Q&A

I have stripped out the threads on the fill plug on my ATV diff. Any ideas other than re-threading, as that won’t work because there is a crack just above the fill plug as well. Also, is there any way I can permanently repair the crack above the fill plug?

John Talley: That’s going to be the real trick there, isn’t it? Yes, there are several re-threading kits from different manufacturers. But as far as dealing with that crack, that’s the tricky part. Aluminum, in and of itself even when it’s really clean, is hard to weld accurately, if you can find anybody that would even touch it. If you’re talking about a diff which is covered in oil … trying to get that to really penetrate and make a clean weld, I’m not sure how you would do it. Unfortunately, I think you’re either facing getting another diff enclosure or casing, and then having to transfer the internals into it. Or just go ahead and buy a whole differential as a unit because when you move the pinion and the different gears into a different casing, sometimes that changes the lash or the clearance in between the gears. And that’s almost a black art trying to get that shimmed correctly. You didn’t tell me the year, make and model, but if this is a really basic low-power utility ATV, you can probably get away with just taking exactly what you’ve got and pressing it into that new housing. But if it’s a high-power ATV, that’s going to require a little bit of expertise to get put together correctly. I’m sorry this happened. I wish I had a better answer for you, or a less expensive answer for you, but it sounds like you may end up having to replace the whole “chunk”, as I’ve heard it called before.