1986 Honda Aero NB50 stripped crankshaft screw rethread advice.

[ForestTheBoy]

I tried putting in a new ramp plate on my variator, but I guess I should have changed the belt width too because when I impact drove the crankshaft bolt back on it cross threaded pretty bad.

From my understanding it's expensive to replace the crankshaft, and that's not a task I think I'm up for seeing as how bad I screwed this up.

What options do I have to fix this? I hear it may be possible to rethread, but I've got no idea how to do that. If it's not too difficult I'm willing to try, but would any old mechanic be able to rethread the crankshaft bolt?

PXL_20230719_215351736.jpg (536.07 KiB) Viewed 1045 times

[motormike]

You've got some serious damage, friend.
Those splines and threads look roached to me.
I know that I'd never be able to save them,
and I've worked on vehicles for 60 years.

[zz28zz]

I've tried "fixing" threads that were in waay better condition. Wasted hours with a small file trying to re-cut the threads. If it was only 1 thread with damage, you might get away with just using a thread Die, but when it's many threads going all the way to the end, you're done.
A machine shop might be able to weld the threaded area, mill it back down and and re-thread the shaft, but that would costs waay more than it s worth.
Been turning wrenches for 45+ years.

[ForestTheBoy]

I enlisted the help of a handy neighbor and we took a Thread Die to it and screwed a nut on with blue locktite. The damage was mostly to the front of the bolt and the nut sits in close to the deepest threads, so it feels pretty solid. I drove about 6 miles and haven't noticed anything wrong yet. Fingers crossed!

That being said I'm hesitant to tune the variator weights now. But I do want the belt to ride higher up onto the variator for a better top speed. What tuning measures can I take without popping the variator off?