Cam tensioner bolt - busted!

[frenchman1952]

1968 CA77 305:
The cam tensioner bolt broke while trying to loosen it (hey, my first one, not too bad). I can use an extractor, but want to make sure nothing serious happens if I completely remove the bolt. Any thoughts?

[e3steve]

Mine stripped out, so I took the tensioner off and Helicoiled the thread back to M6. You can get 'Recoil' kits from most good tool stores or engineering suppliers; they're not desperately expensive and essential if you're doing all your own maintenance.

I bit the bullet and bought all 6 kits, in stainless, from M4 to M12. Our bikes' alloys, remember, were cast using '50s/'60 technology; castings are soft and threads strip from just a dirty look sometimes. When I tear down my powertrain, later this year, I'll be Recoiling every casing thread.

Stainless, when used in alloys, can create a dissimilar metal reaction when it gets wet and, particularly, if you live near the salty air of the coast. As a precaution against such a reaction stainless bolts and machine screws should be smeared with Tef-Gel Ultra® or silicon grease before installing.

[eyedragaknee]

You have enough material to tap it without a helicoil if you want to and don't booger it up. I think I took mine to 5/16-24 if not mistaken. I don't remember exactly what the tapped size was, but there was plenty of meat to make it work just fine with cutting new threads. $20 at a machine shop to center drill it on a mill might be wise.