I need to clean up the threads inside my crankshaft.

 

Made a mistake using a puller; got a small piece of metal jammed in the crankshaft end but fished it out with some epoxy. I want to clean the threads up before putting it back together.

 

I am measuring thread spec using my crankshaft bolt and calipers. By my measurements major thread diameter = 12.8 mm, thread pitch = 1.5 mm (averaged along 15 threads). Should I assume that the proper tap size = M13x1.5?  (The reason I come here to verify is because M13 isn't a common size, so I want to make sure I'm right before I order the tap).

 

Thanks.

I want to say its M12x1.5

Take the bolt to a Fastenal store, or any store that sells specialty hardware, and they can measure it.