[Jeff Higgins]

To be honest, it didn't actually "blow", but had I kept riding I bet it would have...

I just broke one of the dog teeth off of the countershaft third gear, and one of the gear teeth off of the mainshaft second in my old Ironhead Sportster. I'm pretty sure the dog tooth went first, then took out the gear tooth.

This thing has always been difficult to shift from second to third. It's the only shift that moves a gear on both the main and countershafts, so it has two chances at a "false neutral". If I am very deliberate, I never have a problem and it shifts like butter. If I get distracted, don't pay full attention and release the shifter too soon, it sometimes does not fully engage. I'll let the clutch out and find it's in that false neutral, but then it will bang, really hard, into gear. When I'm on the gas, with the clutch out. I'm sure that's what finally broke it.

So the tranny is out and with my buddy who does this kind of work. We're just going to replace all of the gear sets. The shift forks look brand new, as do the pawls and springs and other little parts. I'm going with Andrews gears across the board, stock ratios on first, second, and third but their "C" set for the clutch gear / countershaft gear. Stock is 27/17 for a 1.588 ratio, their "C" set is 26/18 for a 1.444 ratio. These trannies are notorious for their big gap from third to fourth gear, this "C" ratio set closes that gap a bit by raising the first three gear ratios (fourth is 1:1). I've heard good things about it.

Anyway, I think I dodged a bullet with this one. The broken teeth fell into the bottom of the tranny and didn't break anything else. Could have been a lot worse...