Re-threading a (steel) rear mech hanger
mr.b-campag
Posts: 413
As per the title,
I've straightened a bent hanger on my old steel trainer/commuter but, on doing so, have managed to damage the threads sufficiently that the mech doesn't really site properly on the hanger. Anyone any ideas how I might (ideally simply/cheaply) create a decent new thread (I screwed in the rear mech from the other side to create enough to hold it on but that isn't sufficient)? The shop I took it into suggested some sort of weird and (according to them) expensive tool that fitted a spring-like device that becomes the new thread but I'm wondering if there is not a simpler way to do this?
Thanks
B
I've straightened a bent hanger on my old steel trainer/commuter but, on doing so, have managed to damage the threads sufficiently that the mech doesn't really site properly on the hanger. Anyone any ideas how I might (ideally simply/cheaply) create a decent new thread (I screwed in the rear mech from the other side to create enough to hold it on but that isn't sufficient)? The shop I took it into suggested some sort of weird and (according to them) expensive tool that fitted a spring-like device that becomes the new thread but I'm wondering if there is not a simpler way to do this?
Thanks
B
0
Comments
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The shop are referring to a system of rethreading damaged threads called "helicoiling", it is quite simple, try looking it up on the internet - You Tube.
Not aware of the kit to do this being expensive>0 -
IIRC the thread is the same as crank bolts. Drill the hole out to take a single ring crank bolt half. Hold on place with correct tool screw in the mech.
Ps just check the threads before getting the drill out."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
The thread is M10x1.0 (M10 fine), which isn't that common. I think crank bolts are M8 fine.- - - - - - - - - -
On Strava.{/url}0 -
You could drill the hanger out and fit a dropout saver nut.
Ask at your LBS to order one or buy online.I've added a signature to prove it is still possible.0 -
You could drill the hanger out and fit a dropout saver nut.
Ask at your LBS to order one or buy online.
great option, do this!0 -
Go to local tool shop (proper ne that supplies the trade, not B & Q) and get a thread tap. Use that. Two minute job.Postby team47b » Sun Jun 28, 2015 11:53 am
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honoursmithy21 wrote:
He's right you know.0 -
Thanks all. The thread tap option sounds like the best thing. Just to be clear (I'm a bit mechanically challenged) I'll ask for a M10x1.0 (M10 fine) thread tap (and some kind of handle) and basically just screw this in to create a new thread? Give the thread already exists should I just screw the tap in or should I see if I can get hold of e.g. a hand tap?0
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but as you say there is not enough metal.Thanks all. The thread tap option sounds like the best thing. Just to be clear (I'm a bit mechanically challenged) I'll ask for a M10x1.0 (M10 fine) thread tap (and some kind of handle) and basically just screw this in to create a new thread? Give the thread already exists should I just screw the tap in or should I see if I can get hold of e.g. a hand tap?
you cant make new thread from are. get one of the inserts above."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
Go to local tool shop (proper ne that supplies the trade, not B & Q) and get a thread tap. Use that. Two minute job.
It's a pretty rare thread, not often used. I reckon they'd have to order that in.- - - - - - - - - -
On Strava.{/url}0 -
Go to local tool shop (proper ne that supplies the trade, not B & Q) and get a thread tap. Use that. Two minute job.
It's a pretty rare thread, not often used. I reckon they'd have to order that in.
Indeed - most metric threads commonly used are "coarse" series. And it might be 10 x 1.25 or 10 x 1. Either way the bike shop should have the proper tap in their workshop - so if they say it needs a helicoil, then I'd suggest it does, but by all means try another shop and see what they say. Also 10 x 1 taps are available for £5 on ebay, so not that expensive.0 -
Thanks. I'm inclined to try the tap first and if that doesn't work then I will get a saver nit. Is this what I am after:
http://www.ebay.co.uk/itm/M10-x-1-0-HSS-Hand-Thread-Tap-Metric-Fine-Plug-Bottom-/271925421294?pt=LH_DefaultDomain_3&hash=item3f5004a4ee
Thanks0 -
I did one on a seriously jazzed crank arm thread (where the pedal goes in) the other day - I took the crank arm to the factor, they dug the tap out of their store, half an hour and a tad of carefulness later, job jobbed.
Decent quality tap cost me a tender and now it's in the tool box for life.
if you're not too sure what size you need take the tap and in let them sort it - it's probably a fairly common size tbh...........
Dependent on how good you get it you can make up some gap by wrapping the thread in PTFE tape or drop some thread lock in there.Postby team47b » Sun Jun 28, 2015 11:53 am
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honoursmithy21 wrote:
He's right you know.0 -
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I did one on a seriously jazzed crank arm thread (where the pedal goes in) the other day - I took the crank arm to the factor, they dug the tap out of their store, half an hour and a tad of carefulness later, job jobbed.
I know this post is in English however it is not a form with which I am familiar. I interpret it as you have damaged a crank pedal thread and fixed it by running a tap through the crank. This may make it possible to fit your pedal but it has not repaired the thread. Your pedal/crank connection is now seriously weakened and will probably fail again.
Get it helicoiled before that happens.0 -
I did one on a seriously jazzed crank arm thread (where the pedal goes in) the other day - I took the crank arm to the factor, they dug the tap out of their store, half an hour and a tad of carefulness later, job jobbed.
I know this post is in English however it is not a form with which I am familiar. I interpret it as you have damaged a crank pedal thread and fixed it by running a tap through the crank. This may make it possible to fit your pedal but it has not repaired the thread. Your pedal/crank connection is now seriously weakened and will probably fail again.
Get it helicoiled before that happens.
I have interpreted your pomposity over the grammar and sentence structure of the informal post as above and decided that overall, nah, it's like pukka mint and will be kosher. Ta muchly anyhow.Postby team47b » Sun Jun 28, 2015 11:53 am
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honoursmithy21 wrote:
He's right you know.0 -
You've screwed in the mech from the rear and found that inadequate, and the LBS are suggesting a Helicoil, so I'm thinking it's probably buggered beyond just running a tap through it. The anecdote about the crank arm doesn't really help; there's a lot less metal to play with in a mech hanger
So either get it Helicoiled, or drill it out and then use one of those natty dropout saver nut things.0 -
Thanks keef66,
That's probably a fair summary. The thing is the shop I took it to (Decathlon) told me that this is what is required but didn't say they could do it for me - they said I would need to buy the tool and it would be expensive (which has been questioned in this thread). I don't have access to any power tools (or the skills for that matter) here in London - is the helicoil procedure something that a bikeshop would take on?0 -
Thanks keef66,
That's probably a fair summary. The thing is the shop I took it to (Decathlon) told me that this is what is required but didn't say they could do it for me - they said I would need to buy the tool and it would be expensive (which has been questioned in this thread). I don't have access to any power tools (or the skills for that matter) here in London - is the helicoil procedure something that a bikeshop would take on?
Buying the kit to do it yourself would be relatively expensive unless you're planning to do this again. Ring round a few bike shops, see if any offer the service. Failing that, try garages / motor engineers.
The dropout saver nut is a DIY job if you have a drill.0
