thread repairs

[bunnym0b]

I've done the mechanical refresh up to a point> New cables, Campagnolo gear shifter, front derealieur, crankset peddles bottom bracket (and dust cover) it's all good and will have some new (to me) wheels (Period 5 gears French made). A new chain is on order. However there is a problem with the rear dropout. The threads are stripped so that the Italian threaded Campagnolo derailleur wont stay fixed. The sun tour was reverse mounted with a bolt running through the pivot bolt-thats not an option at the moment as i have the most useless item to affix... more later.
So I'm looking for someone in London who will undertake the repair. Condor says no, so does my local bike shop. It would be done in conjunction with a respray. Can anyone in London or beyond give me a steer for the repair and a respray/powder coat?

 

[raleighnut]

Does it go through far enough to get a thin nut on the back,

 

[rogerzilla]

You need an M10 x 1 Helicoil insert, if one short enough is made. Any decent garage should be able to do it.

 

[Profpointy]

Is there enough meat on the derailleur to drill the (presumably unthreaded) clearance hole the next size up? If so you could drill and re-tap the dropout the next size up. Assuming I've understood the problem / which bit is stripped

 

[Ajax Bay]

I wonder whether going down this line might be an option. You'd be drilling and tapping a 'full thickness' of fresh metal before respray. Once resprayed it would be inconspicuous.
https://www.ebay.co.uk/i/141021947534?

I have not attempted this and the image and link is not a recommendation, it's to illustrate the idea.

 

[bunnym0b]

Does it go through far enough to get a thin nut on the back,

View attachment 552091

yes it would which is an elegant solution.

 

[bunnym0b]

I wonder whether going down this line might be an option. You'd be drilling and tapping a 'full thickness of fresh metal before respray.
https://www.ebay.co.uk/i/141021947534?
View attachment 552119
I have not attempted this and the image and link is not a recommendation, it's to illustrate the idea.

ive looked at this as an option and may do it. ive also sourced a set of dropouts which could be welded in. At some point however the cost begins to become an issue-its a Sprint, albeit one that fits me, and is in otherwise reasonable shape.

 

[raleighnut]

yes it would which is an elegant solution.

It is possible you have a suitable nut already, the cone locknut of a rear hub is the same thread and thin enough.

 

[Ajax Bay]

Does it go through far enough to get a thin nut on the back

an elegant solution

Without wishing to 'diss' that 'elegant' option unreasonably, I fear that the number of threads you'd get engaged would not be enough to keep the RD stable even if it was sufficiently secure and, as @screenman irregularly reminds us, vertical/unchanging rear mech alignment is essential for its effective function. There's a fair bit of leverage on an RD.

 

[raleighnut]

Without wishing to 'diss' that 'elegant' option unreasonably, I fear that the number of threads you'd get engaged would not be enough to keep the RD stable even if it was sufficiently secure and, as @screenman irregularly reminds us, vertical/unchanging rear mech alignment is essential for its effective function. There's a fair bit of leverage on an RD.

If you look at the dropout there ain't a whole thickness of metal on that either.

 

[Ajax Bay]

1/4"? Surprised that the RD bolt will have enough showing the other side to get even a cone locknut on. But worth trying, easy to try and you've lost nothing.

 

[raleighnut]

1/4"? Surprised that the RD bolt will have enough showing the other side to get even a cone locknut on. But worth trying, easy to try and you've lost nothing.

My guess is 1/8th inch steel 'stamping' so roughly 2.5 mm.

 

[weareHKR]

Can you ask a local engineering company go re-tap the hole to 12mm & turn you a new securing bolt with 12mm thread?

 

[DRM]

Can you ask a local engineering company go re-tap the hole to 12mm & turn you a new securing bolt with 12mm thread?

Or would it be possible to fill the hole with weld, flatten off then drill and retap the thread?

 

[C R]

Or would it be possible to fill the hole with weld, flatten off then drill and retap the thread?

Wouldn't the weld/frame join be a weak spot?