Anyone use helicoils...? Much sadness.

My_Teenage_Self · Aug 31, 2016

Bit bummed really...

One of my NOS Kooka hydraulic (magura) levers have a stripped thread in the bleed port

it's a standard m3 x 0.5 thread.

I'm happy to helicoil it, but has anyone got an M3 helicoil that they could measure for me? There's VERY little material around the thread, and I'm worried that there's not enough for a helicoil... but I honestly don't know how much an M3 helicoil will need?

Can anyone help?

or any other Ideas...?

02gf74 · Aug 31, 2016

What do you want to fit in the hole? Bleed nipples are available in larger size.

If you can take it apart to remove rubber seals, presumably being alloy, could fill the hole witb lumiweld then drill and retap,

My_Teenage_Self · Aug 31, 2016

it's a funny little plug. imagine a grub screw with a point on the end. the taper on the pointed end seals the lever. I'm very reluctant to damage the taper in the lever

Lumiweld and similar ( I've got and used Durafix) require heat, and would wreck the anodising

02gf74 · Aug 31, 2016

Cant you tap to m4 then take m4 stainless grub screw and make a pointy end? Ive done it with shimano callipers successfully. Hold the grub screw in drill press and use a file, although a lathe would be ideal.

.... but isnt there a fitting that goes into it? This type of arrangement is common on hyraulic disc brakes, the grub svrew is remove to fit an adapter to which a syringe is fitted. Once bled , adapter remivec and grub screw fitted.

My_Teenage_Self · Aug 31, 2016

I guess the question really is " is an M3 helicoil smaller than a M4 thread?"

the taper provides the hydraulic seal - metal on metal.

No fitting was supplied, and these can be bled by just pumping fluid out of the hole.

This isn't my lever, but you can see the tiny grub screw here.

02gf74 · Aug 31, 2016

Outer diameter 3.80 to 4.35 mm. No idea why there is 0.5 mm variance.
M4 drill is 3.3 mm.
Theres not a lot of metal around the port.

Do m3.5 grub screws exist?

My_Teenage_Self · Aug 31, 2016

OOOooo Where'd you find that?

*runs off to measure lever*

02gf74 · Aug 31, 2016

I think min and max are internal and extetnal diameter?

M2.5 helicoil would need smaller hole (3.3 mm from memory)and grub screws are available.

http://www.helicoil.in/pdf/helicoil%20catalogue.pdf

Simplest, cheapest and safest due to metal around hole would be 3.5 mm grub screw if there is sufficient metal for thread, else m2.5 helicoil.

My_Teenage_Self · Aug 31, 2016

*trudges back to computer*

that whole section is barely 5mm wide

I reckon there's less than a mm of material either side of the grub screw, which pretty much rules out drilling it out any bigger?

2.5 is 3.7mm max (According to that link!)... leaving maybe 1.3mm... or about 0.6mm material either side. :facepalm:

I'm starting to think that I may need to explore other options...

andyz · Aug 31, 2016

Re:

M3.5 grub screw do exist. That might be the best option.

Anyone use helicoils...? Much sadness.

My_Teenage_Self

02gf74

Old School Grand Master

My_Teenage_Self

02gf74

Old School Grand Master

My_Teenage_Self

02gf74

Old School Grand Master

My_Teenage_Self

02gf74

Old School Grand Master

My_Teenage_Self

andyz

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