Another taper pin caper

[pczar3]

Well I launched into the nose gear taper pin mod a week ago. After the ACS taper reamer and one from an east coast company I finally learned how to sharpen the ACS reamer and finished the job. Sore arms, sore back and plenty of oil everywhere. Now I have spent the last two days looking for the torque specs for the AN386 taper pin nut. I have looked in 4 FAA manuals, searched the web and looked on manufacturers sites. Can any one please tell me what the proper torque is for the taper pin nut?
Thanks in advance for the help.

Paul

[RVDan]

The taper pin is a shear device so torque isn't critical as long as the hole is clean lightly lubricated and the pin is lightly seated with a tap of a mallet. I might suggest using the standard torque for the nut you are using. If it is a shear nut it will be quite low.

[pczar3]

Thanks for the answer. The whole taper pin retrofit was interesting. I think what I was facing was work hardening of the steel from the original bolt drilling and the "S" drill. It really did a number on the ACS reamer. What I found was that I could sharpen the ACS reamer with a sharpening stone and then nicely create curled chips for a while. When it stopped making curls, I switched to the spiral taper reamer I bought and that would produce nice curls for a while. Then it was back to sharpening of the ACS reamer and repeat the whole process. The end result took a lot of work, several hours but I finally got a nice tapered hole and setting the torque was the final step. Another step forward on my glacially slow build!
Thanks,
Paul

[BillL]

Those pins can generate huge contact stresses with higher torques. I am looking for a easily used formula, but here is a link that has what you would need to calculate the stress for that joint. You can use yield stress for 4130 at the external tubing as the limit. The torque conversion to pin contact stress is the next issue. Still searching.

http://www.mitcalc.com/doc/pins/help/en/pinstxt.htm

OK, I found a torque-tension equation, but it is only for standard threads, not SAE fine.

http://www.engineersedge.com/torque.htm To use, you will need to lubricate the pin and threads to get an accurate installation using fraction factor of .2

Good Luck.