Hi Kats, Here's another concept for the lug nuts. I don't think this is what they did (I think they forged it into place), but if you really want to completely hide the retaining feature to confuse your competition, here's one way I came up with to do that. Again, since this is proof of concept only, I took shortcuts. Most noticeably, I did not make a tapered ring this time, but instead just used a simple cylindrical collar as it was much easier and does not affect the viability of the test.
I cut a groove on the inside of the collar and drilled two holes through the "nut" body:
I then pressed two small pins into the body:
I pressed the pins flush with the outside diameter of the body:
The lengths of the pins are such that when pressed flush with the outside, they protrude into the inner portion of the body:
I made a mandrel a few thousandths smaller than the ID of the nut body and tapered it on the end. I used a portion of an old bolt because it has a quality heat treat of at least grade 8.8:
While the pins are flush with the outside, slip the collar over the body, put the mandrel in place, and press the mandrel into the part on the arbor press. When you do this, it forces the two small pins outward and they catch the groove in the collar:
Thread the ID and you've got a retained collar with no externally visible retaining feature:
I still think they forged it, but it was nice to see this more elegant method work.