So say a guy had a 24,000 pound snatch strap and 4 3/4 ton shackles. Is this a bad combo? Even with the elasticity factor?
Also What do you think the stock trailer hitch on an FJ is rated at? Can I pull people out of a mudhole with my Warn 2 inch trailer hitch shackle safely?
As FJNewb has already schooled us, the off-road community is pretty unregulated regarding what these 'ratings' for shackles and straps actually mean. While this is not a bad setup, I am going to go out on a limb and say this is not an "ideal" setup for the FJCruiser and agree with CVKurt's suggestion that a recovery damper will help mitigate your risks. Not intending to be a nagging nelly but solely for keeping with the purpose of increasing education and awareness, I don't think the setup you described is as safe as you can get.
Regarding snatch straps: According to BushRanger
LINK in Australia, recovery straps should ideally be rated at 2-3 times the Gross Vehicle Mass. Recovery straps are designed to stretch up to 20% to obtain the correct amount of kinetic energy to "snatch" a vehicle free. BushRanger goes on to state the life of the strap is up to 10 vehicle recoveries or per their safety/inspection instructions. ARB does not make that statement that I have found. Since the FJ Cruiser is roughly a 4-5000lb vehicle this requires a Recovery strap in the 8-15,000lb rating range. I think the ARB705 is a better match for our vehicles with it's 8t / 17,500lb rated minimum break strength.
It is my understanding that a 24,000lb recovery strap (such as the ARB710US) is considered a "heavy" recovery strap. The 24,000lb rating is a minimum breakage value and this value can easily exceed the working load limit of a standard 4.75t bow shackle and possibly it's 4:1 safety factor in some cases. Also, the heavy rated recovery strap may not allow the proper amount of 20% stretch for our roughly 5x smaller vehicle size. This ultimately places a greater load on the recovery points and vehicle itself due to less 'give' and increased shock from jerking on the strap during the recovery.
Some thoughts to consider:
1. There are very few SUV style vehicles that have a 24,000lb rated winch (even when adding a snatch block pulley to smaller winches) so, honestly, when would a 24,000lb recovery strap be prudent?? Note to self: I am guilty of having a 21,000lb recovery strap and need to figure out it's intention for my overlanding plans.
2. It is generally considered ideal to design a recovery system such that the strap or rope will fail first. The idea being to minimize the chance of breaking an attachment point and causing it to become a lethal missile or damaging the vehicle. Mad Matt's video that CVKurt shared is a pretty good example of this bad idea and just proves the point for a lower rated Recovery strap and/or better rated (and properly used) attachment points.
Regarding OEM hitch: Class III hitch, Six attachment points, 500lb tongue weight / 5000lb gross tow weight rating. I would not go hog wild but I think you are ok pulling people out with more appropriately sized recovery gear. Hopefully the rest of the information here will help give you some ideas.
Regarding shackles: Some manufacturers state the safety factor, some don't. Some offer a warranty period, some don't. Some disclose how their shackles are made, some don't. Some are regulated to meet gov't standard, some are not. The better rigging manufactures regulated for overhead lifting are much clearer on these details and much safer to use.
Most of the regulated/rated for overhead lifting Recovery shackles are manufactured with a stated 4:1 or 5:1 safety factor. This puts a 3/4", 4.75t shackle at an ultimate fail somewhere between 19-25 tones depending upon manufacturer. Differences in cast vs. forged vs. forged/tempered will shed considerable light when deciding what to buy from whom. But the point is this: a 24,000lb minimum break strength Recovery strap can easily exceed both inferior rigging and our vehicles design if you are not judicious.
Hence the emphasis of doing a little homework so you can make a fully informed choice. I can attest that price is not the best indicator. Case in point, I paid a little over 8$ for the
forged steel TJM Bow shackle in my previous post vs. 13$ for the
cast steel Koch Farm implement shackle from my local Big R farm store. Considering both are unrated for overhead lifting and therefore not regulated to meet the higher gov't standards, the forged one is a better choice. Forging aligns the grain and eliminates any voids in the material that could contribute to weakness. So, this is proof in the pudding for me that you don't necessarily get what you pay for when you don't know any different.
My ultimate plan is to have something like these regulated Crosby 209A 5.00T shackles (1017516) as standard equipment. These are the ones with the 3/4 size screw pin.
https://www.amazon.com/Crosby-5-00Ta-Anchor-Shackle-1017516/dp/B00B0XV8BG/ref=sr_1_1?srs=9371277011&ie=UTF8&qid=1468566616&sr=8-1&keywords=1017516
Spec sheet:
Crosby® 209A Alloy Screw Pin Anchor Shackles - The Crosby Group
I will upgrade my current TJM shackles at some point in the future and use them as a spare set as long as they remain in serviceable condition.
Learn about your gear, buy what you can afford, inspect it often, upgrade what you can as soon as you can, and in the meantime proceed with caution. :cheers:
