Stripped Engine mount thread; ideas?

[G]

The story:
(Skip to the situation bit if bored easily)
My crash bung got ripped out at Snetterton, when I crashed last year. It seemed it had mashed the thread, as I had trouble getting some another crash bung bolt that had come with the bike in; but the thread on the bolt wasn't great either.

Eventually I ordered a new bolt, as the old ones had been slightly mashed anyway. Ended up with this bolt getting mashed as well, so got a Tap and die for it. Die got my new bolt back into shape, but wasn't sure how great a job the tap was doing; resistance to turning all felt a bit weird.

Tried the bolt again, same thing, comes out with a mashed thread.
Tried the tap again, this time the tap came out worse for wear.
After much fiddling, swearing and hitting I found out that the previous owner had used a thread insert; but of the wrong size for all the spare bolts he had included with the bike. Wooo.


The situation:
Unfortuantely, that means I had mashed the insert a bit, so had to remove it. So I now have a thread that did have an insert, but no longer does.
Means that it's probably going to be too big a diameter to get another insert. I'm not sure of what brand the original insert was.

The thread is 'blind'; there is no hole on the other side I could put a nut on.


The question;
Any ideas what I can do to get it holding a bolt again?
Incase anyone needs to know; it's a M12X1.25 pitch (a moderately odd size).

Ideally I want to keep the same diameter bolt, as it would be a fair bit of hassle to change other bits to match, I suspect, but a bigger diameter bolt is one possibility.

[garth]

Helicoil.

If you can find one the right size, although I believe they are realtively expensive.

I suppose another option would be to build the hole up with weld, and then tap the hole out again, but I think a helicoil is your best bet.


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You ain't a has been if you never was

[G]

It has already had a helicoil-stlye thread.
This has been removed.

You need to drill out the old tapped-thread and re-tap with the helicooil tap, but the hole would be too big already, so the recoil tap would be unlikely to have much effect.

The bike is an r6, if anyone cares.

[TheShaggyDA]

Although I know of them, I've not played with Helicoils - is there a chance of putting one Helicoil within another? So the first brings the hole diameter down, and then the second actually provides the thread size you need?
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[i:6e3bfc7581]But still I fear and still I dare not laugh at the madman...[/i:6e3bfc7581]

[G]

Nope, not really. You drill out the thread with a non-standard size drill, then use a non-standard size tap to tap the thread for the insert. The insert is a standard size, but the tap that it is sitting in is not standard sized.

[mr.z]

The only thing i can think might be helpfull is steel putty, the chemical stuff... once its set it can be drilled and tapped allthough any real load bearing is absoloutely out of the question imo but for crash bungs it would be perfect they are supposed to scarifice themselfs right? it might stand to be droped on it, dont know about being thrown up the road...
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>RidingSkills<->Tech Tips<->MyBikes<

[G]

This crashmushroom is on an engine/frame mount, so techincally should be load bearing.

[mr.z]

[Kye]

When my exhuast stud snapped, we drilled it out oversize, tapped it and put a massive stud in there, we then filed that flush and drilled and tapped that stud to the original size I needed. It held up better than the original too, as the exhuast brackets just kept snapping after that instead of the manifold studs.
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Ducati 600SS
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[ZRX61]

[Patto]

Wow I like the sound of the massive stud filed down etc.
I used to crew on a dragbike team and desperate times needed
desperate measures , we never resorted to that one but it sounds
great to me, must bear that one in mind.

I have used Timesert inserts available from Wurth.

They are excellent and give a professional solution, they are available in individual size sets but are quite expensive

not sure if they have the size you need tho

Patto

[G]

Those 'timeserts' look good, might give it a go as they do 'bigserts' for places where an insert has already been used and removed.

Now, need to see if I can get one delivered on friday .