To D-Ring or not to D-Ring. Thoughts?

[HoosierT]

Not sure what experienced folks do, but I’ll lob this out and see what folks think:

I wanted a rear recovery point so I bought the biggest bolt that would fit the hitch pin holes. And I have a couple soft shackles. So while I have yet to get stuck (it will come..) my plan is to put a loop of the soft shackle in the hitch receiver and the bolt through it to anchor it.

I feel like it’s versatile, light, fast, no major downside other than not looking pretty.

Maybe one downside is that if the rear point was being pulled at a very harsh angle the soft shackle would be under tension over the inside edge of the receiver, but in practice it seems unlikely to end up that way and it would be easy to pad it.

Curious what other folks think that actually are doing any recovery.

I've seen many recoveries done this way and this is the way I will set up mine if I need rear-recovery (except hitch pin instead of bolt). I see no need to buy anything extra. I always keep a pin in my swingcase so I'm always good to go.

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[charwest]

get a D-ring receiver for the hitch. don't use a pin or bolt directly to the strap, and definitely don't use a tow ball, or the trailer breakaway chain loops.

you can get a solid steel receiver on amazon for like $30.

hm. my gut tells me my system is strong enough, and as long as i pad the edge for an angulated pull would not be expected to have bolt failure. i really dont want to buy another thing just to not use it.

a bolt failure by bending would mean a functional recovery and then inability to remove the bolt without a cutoff saw, which honestly would be survivable but undesirable. if that happened and rendered the hitch unusable and a second recovery was needed, i could either put straps or soft shackles around the bars of the receiver, or give up and ask a tacoma to pull me forward instead of back

but folks think this is a liability? that it could break in real world use? has anyone done the math? or some load testing?

it has been over a decade since i did any physics, and i am no mech engineer, but why not ask professor google and do some napkin experiments?

im pretty sure my bolt is a grade 8 5/8" bolt. i picked a long one so that the shank crosses the receiver and no threads would be loaded. effectively it acts like a hardened steel rod/hitch pin.

i dont have an engineering background, so i dont know whether the rated tensile strength is the 'proof' or the 'shear/tensile' load

http://knowhow.napaonline.com/common-automotive-fasteners-guide/
https://www.boltdepot.com/fastener-information/materials-and-grades/bolt-grade-chart.aspx

so ill assume the weaker (proof). 120k psi. not the 150k psi noted for tensile.
5/8" bolt is 0.625" nominal at shank

https://www.engineersedge.com/fastener_thread_stress_area.htm

shank area would be
A=pi*r squared = (pi * (0.625/2)squared = 0.3068 square inches
although the published stats seem to suggest using 0.226 as nominal bolt area
so to keep being conservative, ill use the 0.226 inches squared nominal.

so using this doc on estimating shear strength on a bolt

https://www.fastenal.com/content/feds/pdf/Article - Bolted Joint Design.pdf

i would estimate 2*0.226*120,000*60%= 32,544 lbs rated load. this would be breaking strength presumably, non cyclic load.

lets assume thats better than real life, because in this application the load is applied more like a point along the beam, not distributed as it would be in typical clamped shear load or like a hitch that fills the entire receiver. i have no idea how to calculate this, so ill guess it will reduce strength by 50%. lets guess 16k lbs. and now lets assume if that is breaking strength, then working load would be about a third, which would be 5300 lbs.

and my truck doesnt weigh 5300 lbs, so i think im ok.

/end ignorant napkin math brainstorm.

can someone else comment on this? i cant help but notice that half of the folks on this forum are engineers of some sort..

 

[Deleted member 1634]

hm. my gut tells me my system is strong enough, and as long as i pad the edge for an angulated pull would not be expected to have bolt failure. i really dont want to buy another thing just to not use it.

a bolt failure by bending would mean a functional recovery and then inability to remove the bolt without a cutoff saw, which honestly would be survivable but undesirable. if that happened and rendered the hitch unusable and a second recovery was needed, i could either put straps or soft shackles around the bars of the receiver, or give up and ask a tacoma to pull me forward instead of back

but folks think this is a liability? that it could break in real world use? has anyone done the math? or some load testing?

it has been over a decade since i did any physics, and i am no mech engineer, but why not ask professor google and do some napkin experiments?

im pretty sure my bolt is a grade 8 5/8" bolt. i picked a long one so that the shank crosses the receiver and no threads would be loaded. effectively it acts like a hardened steel rod/hitch pin.

i dont have an engineering background, so i dont know whether the rated tensile strength is the 'proof' or the 'shear/tensile' load

http://knowhow.napaonline.com/common-automotive-fasteners-guide/
https://www.boltdepot.com/fastener-information/materials-and-grades/bolt-grade-chart.aspx

so ill assume the weaker (proof). 120k psi. not the 150k psi noted for tensile.
5/8" bolt is 0.625" nominal at shank

https://www.engineersedge.com/fastener_thread_stress_area.htm

shank area would be
A=pi*r squared = (pi * (0.625/2)squared = 0.3068 square inches
although the published stats seem to suggest using 0.226 as nominal bolt area
so to keep being conservative, ill use the 0.226 inches squared nominal.

so using this doc on estimating shear strength on a bolt

https://www.fastenal.com/content/feds/pdf/Article - Bolted Joint Design.pdf

i would estimate 2*0.226*120,000*60%= 32,544 lbs rated load. this would be breaking strength presumably, non cyclic load.

lets assume thats better than real life, because in this application the load is applied more like a point along the beam, not distributed as it would be in typical clamped shear load or like a hitch that fills the entire receiver. i have no idea how to calculate this, so ill guess it will reduce strength by 50%. lets guess 16k lbs. and now lets assume if that is breaking strength, then working load would be about a third, which would be 5300 lbs.

and my truck doesnt weigh 5300 lbs, so i think im ok.

/end ignorant napkin math brainstorm.

can someone else comment on this? i cant help but notice that half of the folks on this forum are engineers of some sort..

Some of that is right, and you're definitely on the right track. haha But in the end the actual load capacity of the bolt is irrelevant in this instance, because it would be the same whether you're using a strap or a shackle connector like people suggest. The bolt is still the only load carrying member between the strap and the truck. The bolt bending will be more likely as you have summized. But also as you have concluded, this is only a failure for reuse and removal, not overall function of the bolt. At least not in the realm of what it is required to do. You could hang the entire truck from that single bolt and it would be fine.

The only concern would be jerking and impulse loading, since it's not a Class I hole fit so the bolt can rattle around and move. But that's the same concern to be had with a shackle fitting as well.

In the end I think you'd be fine doing it your way, especially with the infrequency of it. Maybe just have a few bolts just in case one breaks and you're still stuck if you want or something. But other than that, let 'er buck and carry on.

 

[Swingpure]

So a stupid question regarding hitch receiver shackles.

Using the ball on the hitch receiver for towing or recovery is a no no, but the shackle on the receiver is okay.

Is that because the bolt on the ball is not strong enough, or the angle on the pull on the ball makes it weaker?

 

[JoeC]

So a stupid question regarding hitch receiver shackles.

Using the ball on the hitch receiver for towing or recovery is a no no, but the shackle on the receiver is okay.

Is that because the bolt on the ball is not strong enough, or the angle on the pull on the ball makes it weaker?

I'm not sure I REALLY understood your question, but I'm going to reply that your using the 'ball' risks your strap/rope/etc.. SLIPPING OFF (with pretty bad spring-back results).
I don't think sheer strength of the ball is the issue.

You want EVERYTHING to be locked down tight when you start applying yanking/towing forces!

Just my opinion.

 

[Radioman]

So a stupid question regarding hitch receiver shackles.

Using the ball on the hitch receiver for towing or recovery is a no no, but the shackle on the receiver is okay.

Is that because the bolt on the ball is not strong enough, or the angle on the pull on the ball makes it weaker?

"Most common tow balls are rated for thousands of pounds of load carrying/pulling capacity when used properly, but that is a static load, not a dynamic, yanking-as-hard-as-possible pull." The tow balls can snap when heavily jerked resulting in a "missile" that can cause injury or death. Don't do it!!!

 

[Swingpure]

Thanks, I knew not to use the hitch ball, but just wondered why. Those two reasons explain it.

 

[P. A. Schilke]

I'm not sure I REALLY understood your question, but I'm going to reply that your using the 'ball' risks your strap/rope/etc.. SLIPPING OFF (with pretty bad spring-back results).
I don't think sheer strength of the ball is the issue.

You want EVERYTHING to be locked down tight when you start applying yanking/towing forces!

Just my opinion.

Hi Joe,

There is a difference in the way the dynamic load is applied. In a trailer ball, there is a tensile load on the trailer ball bolt or stud/nut and a possibility that the stud/bolt will snap in a bending/tensile load application. With a shackle the bolt is in shear and significantly more robust in shear. Shear is like scissors trying to cut through a steel plate for example.

Here is one many folks do not realize...a Grade 5 bolt or a 8.8 grade metric bolt is much stronger in shear than a Grade 8 or a 10.3 metric bolt.

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[charwest]

Here is one many folks do not realize...a Grade 5 bolt or a 8.8 grade metric bolt is much stronger in shear than a Grade 8 or a 10.3 metric bolt.

tell us more..

because the 5 will deform instead of fail catastrophically? is it magic?

for my application (bolt instead of hitch pin for poor-man's rear tow point) would it make a difference to go to the 5 instead of my 8? or are both overbuilt for this application?

 

[jss81258]

Hi Joe,

There is a difference in the way the dynamic load is applied. In a trailer ball, there is a tensile load on the trailer ball bolt or stud/nut and a possibility that the stud/bolt will snap in a bending/tensile load application. With a shackle the bolt is in shear and significantly more robust in shear. Shear is like scissors trying to cut through a steel plate for example.

Here is one many folks do not realize...a Grade 5 bolt or a 8.8 grade metric bolt is much stronger in shear than a Grade 8 or a 10.3 metric bolt.

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

Ok, I think this is the second time I've seen this. So, how does that work?

References I've seen say that shear strength approximately equals 60% yield, and grade 5 has something like 40,000 psi less yield than grade 8. This suggests that the grade 8 bolt would be the better bolt for shear. It is interesting that no one seems to test for shear strength, or at least I haven't seen it.

We typically use A193 B7 studs with A194 2H nuts, and almost never use automotive stuff although our rotating equipment guys probably do. We're looking for strength at higher temperatures and will sometimes use even higher grades (B16). So I have limited experience with automotive bolting other than when replacing stuff on my vehicles. I then try to use whatever the engineers originally used.

 

[P. A. Schilke]

tell us more..

because the 5 will deform instead of fail catastrophically? is it magic?

for my application (bolt instead of hitch pin for poor-man's rear tow point) would it make a difference to go to the 5 instead of my 8? or are both overbuilt for this application?

Hi Char and Tony,

Yep. Grad 5 will yield without breaking where the grade 8 will "snap" in shear. Grad 5 can not be torqued to the same value a grade 8 can withstand for example so not as good as good for tensile (clamp) loading. I know this is hard to believe but we encountered quite a few failures in off road racing and when we advised to the team to use grad 5 fastners in these shear applications, the failures stopped.

When I had a Materials area under me, I had a fastener engineer, Steve M. Super guy...he spend most of his time in the fastener lab conducting testing. I learned this from him and carried it out to our off road teams to the tune of disbelief to begin with, but over time these teams started getting with the idea.

On my racecar I had a front stabilizer bar that had a shear situation to the lower control arm. I kept failing the Grad 8 bolts. Steve suggested a grade 5 and I stopped having failures during the race. Who would have thought.

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[JoeC]

Hi Joe,

There is a difference in the way the dynamic load is applied. In a trailer ball, there is a tensile load on the trailer ball bolt or stud/nut and a possibility that the stud/bolt will snap in a bending/tensile load application. With a shackle the bolt is in shear and significantly more robust in shear. Shear is like scissors trying to cut through a steel plate for example.

Here is one many folks do not realize...a Grade 5 bolt or a 8.8 grade metric bolt is much stronger in shear than a Grade 8 or a 10.3 metric bolt.

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

Phil,
I understand.
I also know that attempting to pull out someone that's stuck has it's risks, beyond shear worries.

Even if you have all the proper gear; shackles (some call them bow d-rings), soft shackles, bubba rope, or the like, etc) things can still go wrong!
And, it will happen so fast your reflexes won't even have time to kick in!

If you're not properly equipped, pulling someone that's stuck with your Ranger may not work out as you thought.
And even if you are, you must understand the danger.

So, I tried to suggest that the LAST THING you want to do is wrap something around your hitch ball shank and go for it!

That's all.

 

[Swingpure]

Does anyone who has switched from the tow hooks to shackles, have a picture of the front of the truck with the actual shackles not in the brackets that hold them? I would like to see how it looks. I could end up not having the shackles on most of the time.

I like the look of the OEM tow hooks and with the soft shackles I have coming, they should be really functional without harming the finish of anything, therefore not really have a purpose for the shackles, but for some reason I feel drawn to the shackles.

Ultimately I might wait until I have larger, more rugged looking tires, as nothing I currently have really says off road, so the shackles might look out of place. Then again they may look unique and give the truck a more aggressive look.

Ahhh, first world problems.

 

[VAMike]

so the shackles might look out of place

Dare I say, like nipple rings in an aging rocker?

 

[DukeCanBuildit]

Does anyone who has switched from the tow hooks to shackles, have a picture of the front of the truck with the actual shackles not in the brackets that hold them? I would like to see how it looks. I could end up not having the shackles on most of the time.

I like the look of the OEM tow hooks and with the soft shackles I have coming, they should be really functional without harming the finish of anything, therefore not really have a purpose for the shackles, but for some reason I feel drawn to the shackles.

Ultimately I might wait until I have larger, more rugged looking tires, as nothing I currently have really says off road, so the shackles might look out of place. Then again they may look unique and give the truck a more aggressive look.

Ahhh, first world problems.

Hey Gary,

Here’s the pic you wanted.

It makes it look like someone forgot to install something - like those long tow bars you see on farm trucks - unless that’s the look you’re going for. ?

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