I’ve got a problem.
My MUni has converted Shimano Deore LX cranks, which means that my left crank is a retapped right crank. For those who don’t know what that means, it means that the threads that connect the pedal to the crank arm have been replaced with something called a helicoil, which means that a righthand crank arm has been rethreaded to fit a lefthand pedal.
My problem is that when I tighten the pedal enough to not come loose, it starts to loosen the helicoil. So when I try to tighten the helicoil, it makes the pedal come loose.
Is the loosening helicoil something I can fix with loctite, or do I have to take some more drastic measure (like replacing the crank arms)? I’d prefer the cheap but effective solutions, so going out and buying a profile wheelset will not work.
I am not familiar with the cranks your talking about but I am familiar with helicoils. If you ever want to get the helicoil out (I dont know why but if you do) use BLUE LOC-TITE if you want it to stay for the life of the unicycle use RED LOC-TITE and if you never want to worry about it until we’re all dead and gone use GREEN LOC-TITE 
When I saw the thread title I thought jeez, another unicyclist getting knee surgery.
I would just use some loctite 262 (red). You can get it at a hardware store usually or from unicycle.com in .5mL bottles. I have some in Philly if you live nearby.
Wrong part of the anatomy. Helicoils are used by old folks to keep their hearing aids in place. 
Do they use them when they want to put a left ear hearing aid in their right ear?
I tried getting the helicoil out so that I could put Loctite on it, but it will only come out about 1/10 of the way. Ironic, isn’t it? I don’t want to force it out just so I can make it so that it can’t be forced out. So I might try putting some on the few threads that get exposed. Who knows? I’ll keep you all updated on this very serious operation (actually, I probably won’t. It’s not that exciting of a story.)
Now THAT’s funny!
And so was that, in a painful kind of way.
I guess I should fess up and admitt that I’m the guy that modified Paco’s crank. I’ve had a bad run lately: first Jagur’s Ti rail adapter breaks - now Paco’s crank …
It’s not a helicoil that came loose. To get left handed threads in a right handed crank I wanted to do something that I thought would be stronger and better than a helicoil. I redrilled and tapped the original 9/16" right hand threads to 3/4" right hand fine threads. Then I made a steel threaded sleeve that was 3/4" fine threads on the outside and 9/16" left handed threads on the inside. I installed the sleeve with Loctite and “staked” it in place. To stake the sleeve I used a center punch and made four punch marks around the joint between the steel sleeve and aluminum crank. The idea was to deform the metal so the sleeve wouldn’t ever come out. Here’s a link showing the sleeve and staking:
http://www.unicyclist.com/gallery/albut00/finished_170mm_crank
The problem though (now that I think of it - DUH) is that screwing in a left hand thread will screw OUT a right hand thread. Again - DUH!
Paco - put Loctite on the threads as much as you can and also re-stake the sleeve by using a center punch to make punch marks around the sleeve and crank junction. I suppose you could stake the back and front too. I did just the back originally. If that doesn’t work let me know and I’ll fix up another crank but this time I’ll make a sleeve with left hand threads on BOTH the inside and outside.
Steve Howard
To be fair, I have been trying to abuse this thing. It didn’t start coming loose until I started taking it into 3 feet of snow and trying to ride down sledding runs and going off jumps. I don’t know if the cold had anything to do with it, but it has lasted pretty well so far. I’ll try your fixes and see if it will help.
Better than Helicoil
There is something better than a hel(l)icoil, I don’t rermember the name. It is a solid piece (not a spring like thing) that has four pins on it. After you screw it in you hit the pins with a special tool (a hammer works if used carefully) that pushes the pins into the threads, locking it in place. It’s said to be as strong as original metal. Also, I’ve seen helicoils jam going in and be impossible to remove.
I don’t know if there are any left hand thread versions, though, let alone right to left hand threads.