Modern Vespa

Ok, when I put on my flywheel I didn't tighten the nut down enough I guess, because not even a 1/4 of a block away it started coming loose and hitting the shroud. So I killed it and walked it back home. I had sheared the woodruff key which wasn't a big deal. I had a assorted metric set from harbor freight and so I put in a new one and this time went about properly torquing it down. In the process I sheared off the whole threaded end of the crank. It just twisted off inside the nut. I was pretty astonished and then pretty pissed. So now to my question, and this my be insanely stupid but I have to ask. Is there anyway I could get a machine shop to sand it down and weld on a new piece and then thread it without splitting the cases. Like while it's actually still in the case. I was so close to having it ready to go and on the road that I'd really hate to have to tear everything apart again. I'm sure you'll all let me know whether I'm an idiot for hoping this is possible lol. So thanks for the opinions and/or ridicule in advance.

nah man, thats just gonna be a loss. im sorry, but you messed up. always use quality parts from a reputable shop. sorry man.

Def wanna get a new crank. You don't want some bodgy repair to come apart on you at 50mph. Plus, if the flywheel starts to slip out of alignment prior to total failure you'll be running with crappy timing - could damage other parts of your top end with misfiring.

Was it a piaggio original crank? If it was, chances are you overtightened the nut to strip the threads like that. Were you using a good torque wrench?

Ok I didn't buy the crank, it was the one that was in the scooter when I bought it. So I didn't screw up by buying low quality parts, but I definitely screwed up over tightening the nut. Also it didn't strip the threads it full on sheared off the threaded section of the crank. That's why I was so astonished, I'm by no means a strong guy so I really wouldn't think it possible to even do that but it happened. Either way you told me what I didn't want to hear but I figured that would be the case. It's just discouraging to almost get everything all back together and have something like this happen. Especially because before the flywheel came loose it was running amazing and I thought ok I just tighten things up a bit and everythings good. I'm not looking forward to splitting the cases, it just going to open up a lot more possibilities for me to mess up. Usually I'm pretty mechanically capable, but lately I've been making a lot of little stupid mistakes with big consequences like this. So I'm not terribly confident.

Forgot to say, despite not being what I wanted to hear thanks for the input.

Good luck and take your time. 8)

Hello

New crank sorry, but I am amazed that you can achieve that sort of torque with a standard torque wrench.

Grumpy

Honestly who's to say there wasn't already a hairline crack and this wouldn't have happen on down the line anyway. Possibly while on the road. That's what I figure was the case.

Perhaps! Some flaw in the metal of yours from production even. It happens.