Should I Tap this Bolt Hole?

[Ski_rush]

While going through the bike yesterday, I noticed that the cover for the front sprocket is missing the lower bolt (see pic). I thought it was strange. I have misc. loose bolts of the same size and even tried using the bolt from the top of the cover. None worked. They went in a little ways and then stopped. I also noticed that all bolts went in crooked. I'm guessing that's why the bolt is not there in the first place.

1. Should I tap this bolt hole? Is there potentially anything there that I could mess up if I tap this and go too far or something?

2. Or, would you not worry about it since the top bolt seems to hold the over pretty securely?

*this is not a pic of my bike, I just found this on the internet to illustrate the bolt I'm referring to.

[Mudflap]

Known weak point. Not much meat there and if you go in too deep you'll find oil. I would see if there are enough threads left to get a stud screwed in and put it in with loctite then use a nylock nut.

[JerryHawk250]

I had to replace the bottom bolt on my Hawk with a slightly longer bolt because the original bolt only grabbed about 3/16" of threads and stripped. Whatever you do Don't drill it any deeper.

[Megadan]

Yep, I had the same issue as Jerry. They don't use a long enough bolt so it only grabs a couple of threads when tightened down so it is super easy to strip and also vibrates out rather easily. Yours sounds like it may have been cross threaded during assembly.

As far as tapping the hole. If you trust yourself enough to do it, then take a bit of straight wire/coat hanger. Find the bottom of the hole and mark the outer edge of the hole on the wire. Measure that length and subtract the thickness of the cover at that bolt hole if the cover was still installed. Measure that distance on the drill bit and/or tap and then wrap a bunch of tape around the outside at that mark to make a depth stop. That should keep you from going into bad places.

I would say start by trying to chase the threads with the tap. A couple of the threads might just be boogered up. Then get bolt a bit shorter than the length you measured (plus cover) so it doesn't bottom out. Instead of using thread compound, use a washer and a lock washer behind it. Just don't go to town tightening it.

Mudflaps idea of a stud is a good one, and in this instance I would use thread compound. Just make sure the stud has enough stick out to engage the nylon part of the nylock nut - with a few threads showing preferably.

[JerryHawk250]

You will also want to used a Bottoming Tap. This will give you full threads all the way.
http://upload.wikimedia.org/wikipedia/commons/f/fb/TapTypes.gif

[dpl096]

You will also want to used a Bottoming Tap. This will give you full threads all the way.
http://upload.wikimedia.org/wikipedia/commons/f/fb/TapTypes.gif

It still amazes me how many people don't realize there's a difference....using the incorrect tap and then blowing the brand new threads out because the didn't use a bottom tap and felt those 3 or 4 good rounds of threads at the top were plenty good enough.

[Megadan]

Many people also screw up when using a bottom tap and don't take the time to ensure they are starting on an existing thread when using it to chase an already tapped hole out. I've had to fix more than my fair share of double threaded holes because they just cut threads through the other threads.

[wedooit]

We use a product by Loctite called bearing mount, I think years ago was called stud and bearing mount. As suggested above, could use a stud.

[NzBrakelathes]

Maybe just leave well enough alone
If it’s not causing issues that’s ok
It’s just a cover bolt