Help - cross-threaded a built-in rear Mech hole!

[DCLane]

That's the best way to describe it ...

On the 1986 Raleigh Team I had to fit a replacement rear Mech. And managed to cross-thread it.

It's been to the LBS to have a look and they've basically said "no chance".

Now normally it'd be on eBay and I'd have given up. But I've spent FAR too much time on this bike to give up. And it fits me perfectly. So ... I'm wondering whether any of the following might work:

1. Drilling it out and fitting a bolt. I just need to find a bolt that'll fit.
2. Using chemical metal; JB Weld/other to make it fit
3. Fitting it to the rear wheel drop-out using a different rear mech, which I have spare.

Any thoughts please?

 

[Smurfy]

1. Depends on the details of the mech.
2. I wouldn't risk it. Chemical metal isn't that strong (compared to steel), and if it comes adrift mid-ride you have mech in spokes.
3. Could work.

Helicoiling might work, try an engineering workshop.
http://en.wikipedia.org/wiki/Threaded_insert#Helical_insert

 

[screenman]

Are you going to have it painted? If yes, weld, drill then tap. If not a bolt all the way or I seem to remember a hanger that goes on the spindle.

 

[Smurfy]

Are you going to have it painted? If yes, weld, drill then tap. If not a bolt all the way or I seem to remember a hanger that goes on the spindle.

There's lots of options if he doesn't mind repainting. A frame builder could fix it very easily (contrary to his LBS saying 'no chance'), but the heat will mean the paint will be ruined in the locality.

 

[maltloaf]

Drill and helecoil.

A helecoil is a thread within a thread, so you drill he hole out, thread it to the helecoil size then screw the helecoil in. The original derailleur screw then screws into the helecoil. They are very strong indeed, I've even used them on engine blocks to repair spark plug threads !

 

[DCLane]

@screenman and @YellowTim - I'm not planning on painting it. It's basically my 'bad weather commuter', although I am hoping to use it for the 100-mile l'Eroica Britannia this summer. It'll lower the tone.

@maltloaf - any idea how I'd get the size? It's a traditional 80's rear mech.

 

[screenman]

Ebay rear mech hanger, there are loads of options. It may mean grinding off the original hanger.

 

[maltloaf]

I wouldn't know the size but it can't be too difficult to find out.

 

[PatrickPending]

mmm well if you just want to adjust it there are things you put on your shifters to allow adjustment there...

http://www.sjscycles.co.uk/ritchey-ritchey-cable-tension-barrel-adjusters-prod15729/?geoc=us

if you can get the cable routed to its destination and merely want the adjustment, these may suffice.

 

[mcshroom]

Drill and epoxy one of these in. I did that with my Raleigh Criterium frame two years ago and it's been fine ever since

 

[gbb]

You can buy dropout savers, google em, ive never seen one so can't say if they really work...but theyve been around for ages.

 

[DCLane]

Drill and epoxy one of these in. I did that with my Raleigh Criterium frame two years ago and it's been fine ever since

Thanks - that's what I was looking for. I've bought one and they're a bit small but this looks/measures right.

Bought ...

My thanks again to CC for coming to the rescue of a very slow learner. i.e. me

 

[gbb]

Mcshrooms posted exactly what im talking about...

 

[Pumpkin the robot]

Helecoiling would be expensive, the thread is M10x1, not the standard Metric course thread of M10x1.5

 

[Ern1e]

Just to through my bit in (all be it a little late) if the drop out savers don't work you could always try T NUTS these are used in joinery for bolting wood together and are available at most DIY store up to M10 x1.5, these look quite simular to the savers execpt all you need do is flatten the four little spike on them.