Threaded bolt...please help

[don777]

Why am I the only one who seems to be having problems?! Probably because I'm thick!

It's not actually a bolt but the captive thread. I went to do a simple job, putting the gear lever in. Located it fine, 2 bolts went in then the 3rd went in too easily and just didn't grab. I had a look into the hole and it looks like a real mess. There wasn't even a thread.
I put an 8mm tap into it and tried again. It grabbed a little but then let go. So it's obviously bigger than the 8mm bolt.
There doesn't seem to be such thing as a 9mm tap so do you think I'd be able to get a 10mm tap in there?

Should I drill it out carefully with say an 8mm bit (or even smaller to start) and then try the tap?

I've got little/no experience with taps and dies plus it had to be the most awkward one to get at (the single one on the right).

Thanks
Don.

[Big Al.]

What you need to do is to get yourself a 8mm HELICOIL kit you drill and tap a hole a little bigger than 8mm and then wind in an 8mm helicoil (spring) and Bobs your mothers brother.

If you're interested do a search for "helicoil" and see what comes up.

HTH

[don777]

Thanks. Found some Helicoil kits on eBay. For an 8mm coil, what size of drill bit is used to make the hole?

[GreenV8S]

don777 said:

Thanks. Found some Helicoil kits on eBay. For an 8mm coil, what size of drill bit is used to make the hole?

The helicoil kit should say. For some sizes, you can just retap the existing hole directly; no need to drill it out. If you're in a hurry check your local engineering suppliers because thread inserts are quite common and relatively cheap.

[sfaulds]

8.3mm for an M8 helicoil.

[don777]

Thanks. I ended up drilling it out and using a 10mm tap, so it has a 10mm bolt in there now. Bit of a botch but it works.