Thread repair on aluminum fork lowers advice, please

[PeteC]

Bad night in the garage. Managed to overhaul an older Z2 Atom Bomb in near record time, all was going swimmingly, until I bolted on the arch. The first two m5 bolts went in easily, the second two were a little rough. In a rush to finish it off, I just kept torqueing the bolts in despite a bit of resistance. Long story short, the threads in the fork are now damaged. It's beyond simply tapping them back to good repair since there's little bits and pieces of the original bolt in there, too :cry: . I'm thinking of helicoil inserts. Wonder if any one has used them successfully on aluminum lowers? Any other advice is much appreciated. It's for my wife's bike---just had the lowers custom powder coated to match the frame. :facepalm: :facepalm: :facepalm:

 

[B3]

Re:

How much material is around the thread? This may be the limiting factor.

 

[PeteC]

Much of the original thread is still there. It's just bunged up with the remnants of the bolt. Material doesn't seem to be an issue.

 

[bren]

Re:

I use recoil brand inserts at work on all sorts of material.
Should be absolutely fine, especially in this application.

 

[bren]

Just don't try and do it yourself with a pistol drill and hand tools. It will be a drill press or even a mill job if you want it to be a permanent repair.

 

[Rampage]

Re:

How are there pieces of the bolt in there?vHave you tried drilling the bolts out?
They use steel bolts in aluminium legs.

 

[PeteC]

The pieces of the bolt are in there because I tried drilling them out and using a bolt extractor. The bolt extractor bit wouldn't 'grab' the steel bolt--just spun. So I used consecutively larger bolt extractors. After 3 sizes, the bolt just disintegrated. I'm thinking of maybe trying to tap out the remaining bolt material before trying the coil replacement. I ordered 2 helicoil kits yesterday, so I have a few days to try to not make it worse.

 

[Rampage]

Re:

Probably best milling the remainder out and seeing if a tap will remove the rest from the threads. Or if your using a helicoil use a larger end mill and go straight to the dive the helicoil needs.

 

[PeteC]

The m6x1.0 Helicoil Professional kit arrived Wednesday or Thursday. Managed to repair the thread on Saturday in less than an hour (it might have been 15 actual minutes of work and 45 minutes of memorizing the directions, to be honest).

First I tried to simply drill out the remnants of the bolt and tap the remaining thread. But the tap wouldn't catch as there was some damage in the first few threads.

So, I used a hand drill and the rest of the hand tools per the kit and instructions. It all worked really well. Took the little (wife's) bike for spin. All seems to be as new. Sadly, the wife doesn't like the geometry of the bike so the fork will likely need to be replaced with a longer travel one any ways :facepalm: