Wanted XT R/H thumbie mount - or a bright idea to repair a 'hidden' ally threaded hole!

[TreaderSteve]

To quote my father (RIP - his favourite swear-passage) $hit bu@@er @rsehole pi$$ coc% f@rt - the R/H thumbie has a stripped thread - the one that holds it onto the bars.

The pair weren't an Ebay buy, I'll say no more. I don't think the sale was deceiving though, but a repair was done with a product of some sort or another (liquid metal I'm guessing) - which hasn't worked. I was only trying to fit new black ally bolts and not even clamp onto bars yet so it wasn't me!

Might anyone have a decent mount hanging about please? A long shot I know - I'm probably going to have to spend again - just to get the desirable R/H thumbie.

I've looked into helicoils etc, I've used them before on the car, but I'm pretty sure it's not possible as the clamp is in the way - there's no access onto the 'face' of the area that needs the helicoil so can't use a bigger and required drill without jiggering the outer clamp part.

Any bright ideas please (that would last)?

I could tap-out to M6, but an M6 allen head doesn't fit the recess on the clamp so I don't think that's a goer.

Any ideas gratefully received if I can save the one I have!

 

[Twozaskars]

L-R - m6 cap head 9.8mm wide, Shimano Hollowtech II clamp bolt M6 8.9mm wide, M5 cap head 8.5mm wide. Would the Shimano bolt do the trick if you tap it out?

 

[Twozaskars]

Hole is 9.3, correct Shimano m5 bolt is 9.0mm.

 

[legrandefromage]

I drilled out the top of mine and stuffed a nut in it. Its been like that about 15 years or so now

 

[gtturbo]

Try a slightly longer steel bolt. I've had the same problem and a slightly longer bolt picked up a thread and worked ok. I also find some alloy bolts seem slightly undersized compared to their steel counterpart.

 

[trailwright]

@TreaderSteve Take a look at what I did during my GT Avalanche build to sort the same problem out...
https://www.retrobike.co.uk/threads/trailwrights-1992-gt-avalanche-full-xt-build.446563/post-3313138

 

[benjabbi]

I've helicoiled Suntour thumbies that suffered the same fate, worked fine.

 

[Guinessisgoodforyou]

Helicoil as Ben said.

 

[TreaderSteve]

I would helicoil, but I just can't see how as I can't reach the surface I would need to work on - the clamp is in the way. If it were DX thumbies I might be brave enough to open the clamp right out to get access, but can't with XT thumbies.
Sod it - I've used the pillar drill at work and opened the hole through which the fastening bolt passes to 6mm. Tapped the inner, main body part out using an M6 tap - it's introduced what seems to be a decent amount of meaty-enough thread.
The problem now is an M6 allen screw has a 10mm diameter head - the recess into which the head nestles is 9mm. I won't be beaten! Now to persuade a pal to turn a stainless allen hex screw head down to 8.9mm...or get the Dremel out to open up the recess a smidgeon.

 

[TreaderSteve]

I drilled out the top of mine and stuffed a nut in it. Its been like that about 15 years or so now

I just can't picture this with my feeble mind! The stripped threads are in the inner, main body of the XT thumbshifter - if I could introduce a nut into there to become the threads that sounds like a winner - I just can't see how I don't get it!