Carl, the axle has two flats milled into it which removes the threads there. The nut has an un-threaded "collar" which is deformed to match the flats AFTER the nut is torqued.

When you try to remove nut without grinding off deformed area it screws up the last 4 or 5 threads on axel. When the real nut portion is un-screwed past the buggered axel threads they are also ruined and make it almost impossible to get a NEW nut back on (remember old nut is destroyed with/ or without grinding of crimp!!!!). Please sacrifice the nut to save the axel!

Thanks Pancho. Just to be clear, do we use the cut-off wheel to remove only the "peened" area of the nut, or do we cut off the entire area above the "hex" part of the nut?

Mark: Thanks for the offer of pics. I don't think I need any more of this part f the job, but if you document the rest of the job, please consider posting some images of the important aspects of this project.

Thanks Pancho. Just to be clear, do we use the cut-off wheel to remove only the "peened" area of the nut, or do we cut off the entire area above the "hex" part of the nut?

I just cut off the peened part. If you try to get the rest of it off, you will undoubtedly get into the threads and then you'll have trouble. The parts that aren't peened are just normal nut-threads anyway, so there is nothing to be gained by taking them off, and lots to lose by making a mistake, going too deep and getting into the threads. The machined flats have no threads to damage.

My 2 cents.

Thanks Mark and Pancho