Please help.... Helicoil in fork post mount.

[waldog]

So I'm in the situation I've never wanted to be in, I've cross-threaded one of the post mounts on my fork. I'm not going to go into the details as it will only make me angrier.

Anyway, I want to try and resurrect the thread before going down the path of new lowers. I can't say that I'm overly confident going about a Helicoil installation by myself, for starters I don't have a great place to work, let alone all the tools.

Has anybody installed a Helicoil in a fork mount?

Can you suggest somewhere that can do it for me? I'm willing to pay whatever to get it done properly.

Any other suggestions?

I'm absolutely livid over this, PLEASE HELP ME!

Grant.

 

[redbruce]

So I'm in the situation I've never wanted to be in, I've cross-threaded one of the post mounts on my fork. I'm not going to go into the details as it will only make me angrier.

Anyway, I want to try and resurrect the thread before going down the path of new lowers. I can't say that I'm overly confident going about a Helicoil installation by myself, for starters I don't have a great place to work, let alone all the tools.

Has anybody installed a Helicoil in a fork mount?

Can you suggest somewhere that can do it for me? I'm willing to pay whatever to get it done properly.

Any other suggestions?

I'm absolutely livid over this, PLEASE HELP ME!

Grant.

Where are you located?

Oh and this should be in the Parts n stuff section.

 

[.:ROBBO:.]

They are fairly simple to install with simple tools. You can buy the kit with the tap and drill needed. Although I'm not a great fan of helicoils there are times you just have no other choice. In my experiance I have found that most times they only work the once. It's very common for the coil to come back out when you undo the bolt. There are better options than a helicoil but I doubt there is the room on a post mount boss.

Most good bike shops should be able to fit a helicoil if you are not confident.

 

[stoo]

I've only ever used my kit once, an M6 on a postie bike engine case. Very simple job, hard to go wrong IMO.
Buy a kit and give it a go, they're a very handy thing to have in the tool kit.
Do you have any un-mashed thread further up the post? Try a longer bolt into fresh thread?

 

[Dales Cannon]

Do you have any un-mashed thread further up the post? Try a longer bolt into fresh thread?

If there is good thread, at least three or four in depth, you could also make that a stud. Get a long M5 (?) bolt and cut the head off. Loctite that in place and use a nut on the the exposed thread. Don't go too long just enough to run the nut on and one thread exposed or even with the nut.

Helicoiling is good but if you drill the tapping hole off square or off centre you will have big problems. Be careful that's all if you are going to drill it out. Get some people to guide you if you do it by hand. A drill press is the best option.

 

[SummitFever]

To do something like this you really need to use a milling machine so you can properly clock up the post mount surfaces to ensure you get the helicoil hole drilled straight. Any vibrations, run-out or skew drilling will result in the hole being too big and the helicoil not binding properly. If you do it right, the helicoil will not back out and the fix will be much stronger than the magensium/alu threads it replaced.

If you don't own a mill I'd get your local engineering shop to do it for you. They will have the helicoils and possibly some shorter blind hole taps that will enable a much longer coil to be inserted in the post mount. You only get one chance at a helicoil repair.

Otherwise, you need to buy a new set of lowers.

And for anyone else, when threading anything into something soft like alu or magnesium, always start the bolt by hand. If you can't thread it in by hand at least a couple of turns something is wrong. If things are tight, its probably because there's threadlocker from last time in the hole. Use the right sized tap to gently clean the threads. If you keep adding threadlocker without cleaning your threads they will flog out as well.

 

[waldog]

Hey everyone.

Thanks for the advice. I've got it sorted now.

One of my mates had a kit already and had done it before. All went well.

Cheers.