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TH moto

99 yz400f heli coil in swingarm (chain guide)

3 posts in this topic

if anyone can help me with this I would appreciate it.

put new fredette chain guide on, 2 bolts go all the way through the swingarm, 1 small bolt goes into a heli-coil in the back but I pulled it out by apparantly over tightening it.

looking at it, is there any option to replacing the heli-coil ? I would hate to do the work and have it pull out again.

apparantly these are used as threads in soft aluminum to give the bolt something to screw into and hold under torque.

thanks.

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I have tapped aluminum just fine and torqued down the bolt pretty tuff. I doub't they would use soft aluminum on the swingarm. I would hope they used 6061 or 7075. I couldn't find the alloy they use but only searched for a minute. You can drill it and tap it and just use the corresponding bolt.

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if anyone can help me with this I would appreciate it.

put new fredette chain guide on, 2 bolts go all the way through the swingarm, 1 small bolt goes into a heli-coil in the back but I pulled it out by apparantly over tightening it.

looking at it, is there any option to replacing the heli-coil ? I would hate to do the work and have it pull out again.

apparantly these are used as threads in soft aluminum to give the bolt something to screw into and hold under torque.

thanks.

The helicoil you refer to was put there as a fix (to stripped threads) by the previous ham-fisted gorilla who owned the bike. It is not an OEM feature. Just replace it (or use a Timesert - better) and put the prescribed torque on the bolt (see the manual) and it should hold fine.

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