Cutting a thread

[Marquezs Stabilisers]

You might see the silver tube inside the black subframe of my Honda FireBlade. It's threaded, or at least, it was. I've never cut a thread before, but that's what seems to be needed now as the bolt just spins (and doesn't tighten!)

Never done this before, so do I just run a tap into what's there? Or do I need to fill the hole with chemical metal or something and start cutting afresh?

The silver bit is welded into the frame so it's not that I can haul it out.

[Leptons]

It looks like a Rivnut or some other kind of threaded insert. If you’ve stripped the thread it needs drilling out and replacing.

[Marquezs Stabilisers]

Leptons said:

It looks like a Rivnut or some other kind of threaded insert. If you ve stripped the thread it needs drilling out and replacing.

Oh dear. Access isn't great...

[E-bmw]

Marquezs Stabilisers said:

Leptons said:

It looks like a Rivnut or some other kind of threaded insert. If you ve stripped the thread it needs drilling out and replacing.

Oh dear. Access isn't great...

From the look of that, you could always cut out the old one & fit another in the other side of the box section, then use a longer bolt.

[WH16]

If you tap it you will need to drill it out to a bigger size (and then use a bigger fitting). A proper tap set will have the correct sized drills, which are often decimal sizes not included in 'normal' drill bit sets. Tapping it to the same size which is stripped will result in a very weak and shallow thread.

However, when drilling it out, you need to be aware that you are now thinning the tube which will also have a weakening effect - is it a major structural part?

Also, use plenty of cutting agent and wind back the tap every rotation to clear the cutting surface, otherwise you will also be dealing with an inaccessible snapped tap too.

[Jazoli]

You can t drill and tap a rivnut, have you tried a long thin wedge down the square tube to stop it spinning? Other than that strip down time, looks like the light is held in with cable ties anyway.

[WH16]

Jazoli said:

You can t drill and tap a rivnut,

Is it a Rivnut? Op suggests the threaded tube is welded to the frame and it is the bolt which is spinning, not the tube unless I've misunderstood his post?

[cliffords]

The mud on the orange part has properly upset me this morning.

[Marquezs Stabilisers]

I need to see if it is a rivnut, access on the inner side (behind the light) isn't great! It does have the slightly squashed look of one so it hopefully will be a case of getting it out and another one in.

And the really dirty bit is the foam that sits under the light, on a 24 year old bike it's a bit degraded! The cable ties for the light is hopefully only temporary as we go along...

[Marquezs Stabilisers]

Jazoli said:

You can t drill and tap a rivnut, have you tried a long thin wedge down the square tube to stop it spinning? Other than that strip down time, looks like the light is held in with cable ties anyway.

I think the thread inside it is borked rather than the issue being it spinning. If access was easier and elsewhere on the bike I'd just cut it off and use a nyloc