Helicoils

[johnt]

Has anyone had success with using helicoils to repair mudguard eye/carrier boss threads in steel frames. I have never used them so any advice would be welcome. Suppliers? Can they be cut to length as they seem to be longer than required? Thanks

[rjb]

It's probably easier to drill it a size larger and run a tap through. If its currently M5 then going to M6 is pretty straightforward.

[rmurphy195]

It's probably easier to drill it a size larger and run a tap through. If its currently M5 then going to M6 is pretty straightforward.

Or try to run a tap through it, gently, to see if you can clean up the existing thread.

For mudguard eyes you might get away with simply removing the threads (if necessary) and just using a nut and bolt, as long as there's clearance behind (ie not fouling sprockets/chain etc), something I've done in the past.

EDIT http://www.namrick.co.uk/acatalog/Home_ ... s_123.html. I'd go with the cheaper option!

[Brucey]

there are lots of other ways of dealing with this problem, and helicoils work least well on short through-drillings, so I wouldn't look to use them in this instance tbh.

cheers

[Ivorcadaver]

It's probably easier to drill it a size larger and run a tap through. If its currently M5 then going to M6 is pretty straightforward.

Agree completely. I tried helicoils on a stripped rack mount, didn't work. Drilled and tapped a 6mm, worked fine.

[videoman]

You can cut Helicoils down to a few coils long and they will still hold. I run a mobile thread repair business and travel within a hundred mile radius of home and repair all types of threads, spark plugs to diesel injector clamps on all sorts of vehicles, boats, trucks and anything with a thread in.

[NATURAL ANKLING]

Hi,
You could always clean thread out with a tap, make sure you use cutting fluid / oil when you tap, steel is easier than aluminium and wont damage much with out any lubricant, oil will do for now.
Degrease thread if any left and insert a screw / bolt with full thread from wheel side (wrong way round) and if it tightens with out much force, even if it doesn't apply some thread lock.
Then just use a nylock nut onto the stud of bolt.

In any case make sure on threads in frame that you use a bolt long enough to protrude right through the part which is tapped so that all the threads are being used and less likely to strip in future.
Always degrease threads, lubricant destroys the friction so more likely to over tighten bolt and come lose in service .
Only use lubricant on threads that really need to without which would prove very difficult to undo.

[MikeDee]

Would a nut work on the backside?

[DaveP]

Always degrease threads, lubricant destroys the friction so more likely to over tighten bolt and come lose in service .
Only use lubricant on threads that really need to without which would prove very difficult to undo.

With all respect I have to disagree with you here. Without lubricant you get more galling resulting in those bits of frame metal sometimes seen trapped in the thread when the bolt is removed. And, of course, on a bike, removing a bolt can be a bit problematic unless it was treated with grease on insertion.
And they all need removing sometime

Keeping them in place? That's where careful initial tightening, serrated washers and regular inspections come in.

[johnt]

Thanks for all suggestions guys. Have tried cleaning thread with a tap but not enough thread left. No clearance to put a nut on the back or reverse bolt. Don't know is there is enough meat left to increase size to 6 mm, but will probably try helicoils and if that fails go to 6mm. Cheers. johnt

[johnt]

Thanks for suggestions guys. Have tried cleaning threads with tap but not enough thread left. No clearance to use a nut or reverse bolt. Don't know if there is enough meat for 6mm, but will probably try helicoils and if that fails go to 6mm. Cheers johnt

[Brucey]

FWIW if you helicoil a thread like that IME it will be just fine until you come to unscrew (or retighten) the screw. Then the helicoil is liable to come out along with the screw. If this happens in the workshop, where you have a ready supply of helicoils etc, no problem, but if it happens by the side of the road you are in trouble.

Because the helicoil is sprung outwards they can normally only be fitted by winding them in using a tool that holds a 'tang' on the bottom of the insert. In a through-drilled part (like a RH dropout) the tang is removed after the insert is fitted (otherwise it will project and obstruct just like the head of a screw will) . This means that the insert cannot be refitted at all easily, i.e. once it is out, it is usually staying out.

Thus I'd suggest that if you use a helicoil on a RH dropout, you might be best off to aim to fit a stud and locknut to the dropout, then to fit the mudguards/carrier etc over the stud and then to finish with a second nut eg a nylock nut that won't come loose. Both the stud and the helicoil can be fixed using threadlock. This way you won't give the helicoil any chance to give you gyp.

BTW if you want a 'quick and dirty' fix then you need do just two things

a) respace the hub +1.5mm on the RHS
b) file the head of a (~25mm long) bolt down to ~1.5mm thickness and fit it facing outwards. You can use a locknut on it and then use it as a stud, as described above.

cheers