The four advantages to using Grade 8 bolt vs. a hitch pin:
- Grade 8 is stronger than the grade whatever standard hitch pin. Gr8 is 130-150KSI, the only numbers I see on a HP is 36ksi from a page in McMasters. Read Table 1 and the "What Grade" discussion bottom of page 8 here: http://www.pirate4x4.com/tech/billav...lts/index.html
Grade whatever will bend and break before Gr8 even starts to bend, much less break. Shear strength is directly related to tensile strength as discussed in the paper above (shear = .6 tensile).
- A friction shear joint is created due to torquing the Gr8 bolt down to at least 150 ft-lbs, while a standard hitch pin or locking pin provide zero friction shear strength. Read more about friction shear joints on the bottom of page 4, same paper as above.
- Torquing the bolt to +150 ft-lbs. eliminates all "slop". Hitch bar is like a rock.
- Increased security over a standard hitch pin. Unless thieves come with 15/16" wrenches or maybe a couple of crescent wrenches, the bolt isn't coming off vs. pulling the pin on a standard hitch pin. However, it has less security than a locking pin, since it does only take wrenches to take the bolt and nut off and then the hitch bar.
I do size my Gr8 so that shear forces are on the main bolt diameter and not on the threads, so I have that covered also.