400ex Head stud repair how-to
Here's a how-to I put together on repairing pulled out studs. There is some mis-information out there if you search, but I assure you that they are 10 x 1.25 pitch.
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I used these inserts that I got from Fastenal. I've talked to guys who say that helicoils are fine, but I liked these better.
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I also picked up the tap and 31/64 bit I needed while I was there. I got everything for around $40.
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First we measured the depth of the existing threads so we'd know how deep to drill.
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Then we marked our depth on the drill bit with a piece of tape so we'd know where to stop.
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Next, we drilled the holes. Mine is a 440, so the holes were right next to the sleeve. You have to go really slow to make sure that the sleeve doesn't push the bit into the aluminum. Get it close, and then when you start drilling it will center itself on the existing hole. I have had guys tell me that they've drilled them with the jug on the bike using a cordless drill, but I already had mine off so we used the drill press.
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Tap the holes, being sure to use plenty of Tap Magic.
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The inserts came with some thread locker already on them, but we wanted to make sure they didn't come out.
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Thread the inserts in. They go into the tapped holes easy.
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There are slots on the top of the inserts that you can use a large screwdriver in to tighten them down.
That's it. It's pretty easy, really. Take your time and there isn't much to it.
