Grade 8 bolt vs hitch pin

[bpoppa85]

Thoughts? I have a 5/8 x 6" grade 8 bolt that i have cut the threads off of and drilled a hole through the center for a hairpin cotter. Got me thinking though if it was a smart thing to use as a hitch pin or just not be cheap and go buy a new hitch pin. Is it safe to use the grade 8 bolt or is it better?

Thanks

[Sooner]

Grade 8 is tough for sure but if it fails and you now have damaged stuff or hurt someone, what happens next.

[sanjuanworm]

Thoughts? I have a 5/8 x 6" grade 8 bolt that i have cut the threads off of and drilled a hole through the center for a hairpin cotter. Got me thinking though if it was a smart thing to use as a hitch pin or just not be cheap and go buy a new hitch pin. Is it safe to use the grade 8 bolt or is it better?

Thanks

5/8" is the OD of the bolt. The weak points are in the trough of the thread pitch. It's not as strong in shear as a solid 5/8" pin. I'd gladly give you a hitch pin in lieu if it meant not causing an issue on the highway.

[bat119]

I lost my pin at the lake, tried a large bolt it got me home however the bolt bent in the middle had a hard time removing it, I always carry a spare pin now $4 Princess auto.

I have no idea what grade it was ?

[bpoppa85]

5/8" is the OD of the bolt. The weak points are in the trough of the thread pitch. It's not as strong in shear as a solid 5/8" pin. I'd gladly give you a hitch pin in lieu if it meant not causing an issue on the highway.

I guess I wasn't totally clear, but i cut the 6" bolt down to 3.5" so the treads are gone. It is 5/8 OD entirely now. I appreciate the offer but if the consensus is it isn't a good idea i'll just go buy another one. I'm not in dire straights just figured i had the bolt and the time to make it.

[blgoodbrand1]

Personally I have / would use a bolt. Pins aren't made out of kryptonite.


Sent from my iPhone using Tapatalk

[bruceba]

sanjuanworm is giving you some solid advise there and I would heed his warning. Shear is the force that the bolt could and would face on a quick acceleration or deceleration. I'm guessing bat119 was using a grade 5 bolt.

[rembo]

I'd trust a Grade 8 bolt over a cheap Princess Auto/Cdn Tire/Walmart hitch pin any day.

I'm sure some of them are mild steel from the deformation I've seen.

[Arty]

I'd trust a Grade 8 bolt over a cheap Princess Auto/Cdn Tire/Walmart hitch pin any day.

I'm sure some of them are mild steel from the deformation I've seen.

This.

It comes down to comparing a known set of properties of a grade 8 bolt or higher in shear and bending loads, versus a 5/8" towing pin from whereever.

Specified bolt properties and proper fastening methods can be found all over the place, especially around here in the oil/gas business. But not so much for hitch pins.

Reputable hitch manufacturers will offer a hitch pin that in their 'opinion' is 'adequate' for a particular hitch rating in typical use. That doesn't really tell me much though. The biggest problem seems to be finding exact ratings for shear and bend resistance for the pins.

I generally feel more comfortable working with known specific properties and approaches of handling material and systems, rather than just taking somebody's word for it. That way I have a much better idea what to expect and what I can and cannot get away with.

Interesting topic though, and there's a ton of discussion all over the internet on it. (As usual, 90% hot air, 9% thoughtful consideration, and 1% formal and correct engineering information.)

[^v^Tinda wolf^v^]

Structurally it should be fine although by cutting and drilling you have now changed the structure of the grade 8 bolt, mostly on the modified end. Old school says it should be okay but do know it's now all on your shoulders for liability concerns. If the pin was engineered and had a flaw, broke off and killed someone it would most likely stand in your favor as a freak accident from a legal aspect. The "homemade" fixtures are not as accepted as they once were and everything must be engineered to meet transportation specs now days.

[Arty]

If I was interested/concerned with making a high-strength removable hitch connection using a typical towing receiver, I'd use a kind of friction fitting used in bolted joints for steel frame structures. Not quite as convenient as sliding in a pin and throwing a cotter pin on, but stronger and more stable. And still removable using simple wrenches.

I'd just use a tight-fitting, solid billet ball (or pintel) hitch, and a grade 8 or better bolt or cap screw. Clean off the inner surface of the receiver and outside of the billet, slide in the billet and bolt, and torque up the nut a known amount to put the correct tension across the capscrew for its rating. Just like wheel lug nuts.

The resulting friction force between the billet and receiver faces holds them in place, with shear or bending forces not even entering into consideration. Then spin a couple extra nuts onto the end of the capscrew, tightened against each other (but not against the first nut) to provide a kind of backup in case the main nut gets loose for whatever reason. Of course the bolt itself would be a kind of secondary backup using shear if the main nut ever got loose.

That would also eliminate any knocking, peening, or oval-ing of the receiver holes.

[^v^Tinda wolf^v^]

A regular grade 8 bolt with a stover or nylock nut done up to the end of the threads would be considered worthy from a transportation aspect :)

[Popik]

used to have a shaft PTO driven water truck that had a shear flange on it. We used grade 5 bolts specifically for this as grade 8 would shear and snap easy while the 5's would absorb shock and last. Get a proper pin and your insurance company will have no reason to sue in the unlikely even of a failure

[bpoppa85]

A regular grade 8 bolt with a stover or nylock nut done up to the end of the threads would be considered worthy from a transportation aspect :)

http://i1376.photobucket.com/albums/ah4/mjohnston0227/IMG_20161118_120155_zpsu5ewiahf.jpg (http://s1376.photobucket.com/user/mjohnston0227/media/IMG_20161118_120155_zpsu5ewiahf.jpg.html)

Nylock is a no go anymore

[Arty]

used to have a shaft PTO driven water truck that had a shear flange on it. We used grade 5 bolts specifically for this as grade 8 would shear and snap easy while the 5's would absorb shock and last. Get a proper pin and your insurance company will have no reason to sue in the unlikely even of a failure

A grade 8 bolt will typically still have strength and some elasticity after a gr5 would have gone past its limit and failed. That's why it's a 'higher' grade. It doesn't just mean hardness, but also tensile strength. Shear strength is some fraction of tensile strength (maybe 60%), but it doesn't go negative as tensile strength increases.

There's still some belief out there that increased tensile strength must mean brittleness. Not so, especially with modern alloys.
http://tinelok.com/grade-5-vs-grade-8-fasteners/

https://www.youtube.com/watch?v=FVndKEtazNg
(not too crazy about how he strikes towards his own hand, but he makes the point).

Not quite sure what the definition of a 'proper' pin is supposed to be. What is the tensile strength of a 'proper' pin?

[RavYak]

Grade 8 bolts are higher strength then the average hitch pin. If you were using it with the threaded portion I would have hesitations as you would have stress concentrations that over time could fail due to fatigue but since you used the solid portion of the bolt your pin is stronger then your standard hitch pin and you are fine. The only slight weakness is where you ground the protective zinc coating off the bolt as this area will now rust over time.

As for using grade 8 material for pins anyone thinking it is unsafe should research grade 8 hitch pins which are commonly used as higher strength pins in agricultural equipment for an example.

[bubba 96]

My 5th wheel hitch is mounted to my frame by L brackets all bolts are grade 8, I see no reason it would not work, iv seen numerous guys who do this..

[bpoppa85]

A grade 8 bolt will typically still have strength and some elasticity after a gr5 would have gone past its limit and failed. That's why it's a 'higher' grade. It doesn't just mean hardness, but also tensile strength. Shear strength is some fraction of tensile strength (maybe 60%), but it doesn't go negative as tensile strength increases.

There's still some belief out there that increased tensile strength must mean brittleness. Not so, especially with modern alloys.
http://tinelok.com/grade-5-vs-grade-8-fasteners/

https://www.youtube.com/watch?v=FVndKEtazNg
(not too crazy about how he strikes towards his own hand, but he makes the point).

Not quite sure what the definition of a 'proper' pin is supposed to be. What is the tensile strength of a 'proper' pin?

Awesome post. Found lots of info on the net but most seemed to based on opinion with no evidence. I appreciate this and the links u posted.

[Grizzly Adams]

A regular grade 8 bolt with a stover or nylock nut done up to the end of the threads would be considered worthy from a transportation aspect :)

Always amazes me, 10,000 lbs. of trailer held on by a 5/8 pin and a hair pin clip. :confused:

Grizz

[^v^Tinda wolf^v^]

As RavYak was saying if a bolt was used and tortion was put on the thread portion it could eventually fail caused by a notch break or the notching effect. Same could be said if you put a sharp dent in a bar with a chisel and then bent it in a press, it will always tear or shear at that point first where it was nicked. Judging by the picture of the bolt shown it looks very professional to me. A bandsaw was used and that would also cut at a slower pace which in turn would preserve the temper of the steal for the most part. I would trust it but it still has liability on the builder.

[bpoppa85]

Judging by the picture of the bolt shown it looks very professional to me.

You're making an electrician blush, lol

[RavYak]

You're making an electrician blush, lol

Electrician? You better go buy a mild steel hitch pin from princess auto lol.

[qwert]

snip
Nylock is a no go anymore

?????????????
Please explain.

[CBintheNorth]

It always amazes me how people will go on and on about the suitability of an object without looking down the line.

Ever look to see what's holding the entire hitch on?

Considering that your Gr. 8 bolt with the threads cut off is rated for nearly 30,000 lbs of shear, I'd say you're OK on that end.

[bpoppa85]

?????????????
Please explain.

No threads = no nylock

[BobNewton]

I wreckon you will pull the hitch off the tow vehicle long before you shear a bolt or a pin.

While safe I'm sure. I'd stick to a engineered peice.

[Bergerboy]

Grade 8 is brittle. Grade 5 is a better option. The best option is a pin designed for the job.

[CBintheNorth]

Grade 8 is brittle. Grade 5 is a better option. The best option is a pin designed for the job.

While I agree with your last sentence, I believe the first 2 are a result of flawed thinking. No offense, many believe as you do.
In an apples-to-apples situation, Gr. 8 is always a better option than Gr. 5. While the steel is harder (less ductile), it's ultimate yield strength is higher. This means that a softer, more ductile Gr. 5 bolt will long have failed before the hardness of the Gr. 8 is realized or comes in to play.
In the case of a shear application, which this is, the harder the better.
Again, No offense intended.

[Tactical Lever]

Grade 8 is brittle. Grade 5 is a better option. The best option is a pin designed for the job.

Almost like they're engineered for the job at hand... :scared0018:

[roger]

I'd like to think that the removeabke receiver hitch and pin would be considered consumable parts. If the pin was more durable the receiver hitch it will increase in ID by being egged out and the pin would survive.
in theory the entire assm would require change out.

[CBintheNorth]

I'd like to think that the removeabke receiver hitch and pin would be considered consumable parts. If the pin was more durable the receiver hitch it will increase in ID by being egged out and the pin would survive.
in theory the entire assm would require change out.
A proper sized pin and holes would ensure minimal slop, thus preventing excessive wear.
While I understand what you're saying about premature wear on the non-replaceable parts, you should know that even a Gr. 5 bolt or pin is still harder than the tube used to make the receiver, thus would not be sacrificial.

[Bergerboy]

While I agree with your last sentence, I believe the first 2 are a result of flawed thinking. No offense, many believe as you do.
In an apples-to-apples situation, Gr. 8 is always a better option than Gr. 5. While the steel is harder (less ductile), it's ultimate yield strength is higher. This means that a softer, more ductile Gr. 5 bolt will long have failed before the hardness of the Gr. 8 is realized or comes in to play.
In the case of a shear application, which this is, the harder the better.
Again, No offense intended.

No problem. I should probably take off the ring from my pinky and throw my stamp in the trash too.

[Popik]

A grade 8 bolt will typically still have strength and some elasticity after a gr5 would have gone past its limit and failed. That's why it's a 'higher' grade. It doesn't just mean hardness, but also tensile strength. Shear strength is some fraction of tensile strength (maybe 60%), but it doesn't go negative as tensile strength increases.

There's still some belief out there that increased tensile strength must mean brittleness. Not so, especially with modern alloys.
http://tinelok.com/grade-5-vs-grade-8-fasteners/

https://www.youtube.com/watch?v=FVndKEtazNg
(not too crazy about how he strikes towards his own hand, but he makes the point).

Not quite sure what the definition of a 'proper' pin is supposed to be. What is the tensile strength of a 'proper' pin?


My explanation of a "Proper Pin" was exactly that. The story i told was my own observation of why "I" personally don't think its a good idea to use a grade 8 bolt in this application.

There are those who will say it's fine and there are those that will say its not. In the end a hitch pin; however graded or manufactured is the correct tool for the job and therefore a "Proper Pin"

[denied access]

No problem. I should probably take off the ring from my pinky and throw my stamp in the trash too.

You do know the steel in that ring is from a bridge designed by a PEng who %^*&ed up....

[denied access]

5/8 Case Hardened Hitch Pins shear rating 30000
http://ihitchclipspinssellers.blogspot.ca/

Grade 8 Bolt sheer rating 27920
http://tinelok.com/grade-5-vs-grade-8-fasteners/

I would say pretty close and your grade 8 will totally work. Some other componant will give out long before the grade 8

BUT

Case hardened will probably stand up to repeated shear Loads better

and

As far as i can see the only reason to use a Grade 8 bolt would be to locktite a nut on it to stop people from stealing your hitch (Cheaper than a Locking Hitch

and Curios why if you are making a hitch pin as you did WhY???

Pin is 6 bucks
http://www.princessauto.com/en/detail/class-iii-iv-5-8-in-standard-hitch-pin/A-p4205217e;jsessionid=rw23fzTez588AgBadZUDwWsE.pal-prod-com1

or even cheaper (I prefer these ones)
http://www.princessauto.com/en/detail/5-8-in-hitch-pin/A-p8710626e

Bolt is 5.50 for a 4.5" so probably 6 for a 6" plus you have to cut, drill and grind it And by a R Pin
http://www.princessauto.com/en/detail/5-8-x-4-1-2-in-bolt-grade-8/A-p8056435e

Slow day at Work? ;)

Originally being from saskatchewan I know that to make it truly safe put whatever rusty bolt kinda fits, drill a hole through the threads, insert ardox spike or haywire through hole. If you limp this way for a year or two without a giant wreck that sucker will rust in there so solid you can never remove it.

[Kim473]

Just go buy one.

http://www.princessauto.com/en/b/trailer/trailer/towing/pins-locks-chains/N-14cvj7j;jsessionid=r5OuyqVmZXwlAccDVLzYKF1Y.pal-prod-com1

[CBintheNorth]

No problem. I should probably take off the ring from my pinky and throw my stamp in the trash too.

Good start.

Unless you've also taken several courses in metallurgy to go with that degree, I'd keep the ruler in your drawer for now.
Good day.

[CBintheNorth]

Just go buy one.

http://www.princessauto.com/en/b/trailer/trailer/towing/pins-locks-chains/N-14cvj7j;jsessionid=r5OuyqVmZXwlAccDVLzYKF1Y.pal-prod-com1

Agreed.
Unless the OP has free bolts and nothing but time....

[^v^Tinda wolf^v^]

Just go buy one.

http://www.princessauto.com/en/b/trailer/trailer/towing/pins-locks-chains/N-14cvj7j;jsessionid=r5OuyqVmZXwlAccDVLzYKF1Y.pal-prod-com1

That's no fun :)

On another note,
A person can receive an infraction for leaving your hitch in place while not being connected to a load. :scared0018:

I can see a nylock not being sufficient enough for transport Canada anymore and being replaced with the stover nut, I wasn't aware it was code though :thinking-006:

A nylock is good for a first use application and can still be reused as long as it wasn't installed with a numatic air tool although the preferred choice is to discard it and use a new one. I feel much better using stover nuts for most things when I installed bolts in the past. Some areas the stover nut has been required by code for several years on major tie down points such as mounting a pintle hitch on a gravel truck etc.

The problem using a threaded bolt that is needed for an application such as a bumper hitch is the length of meterial before the threads start. Most often on a standard bolt the unthreaded portion stays at one length until you get up into a 6 inch length bolt. It would work just fine for such an application but would look a little goofy. I didn't use the technical terms for defining a bolt but give me a break, it's been twenty years since I got my red seal :) and even then I don't recal if bolt identification was in the welding bible :thinking-006: besides knowing how to read the grade of bolt of coarse, that part I remember!

[IGS]

That's no fun :)

A person can receive an infraction for leaving your hitch in place while not being connected to a load. :scared0018:



Please provide a reference for this. back it up with a linky.:thinking-006:

[^v^Tinda wolf^v^]

Please provide a reference for this. back it up with a linky.:thinking-006:

Sorry I don't have a link for you but I do know it is law and you can receive a ticket if someone is in a cranky mood.

[IGS]

I've tried to find that law on the books in the past and haven't been able to do so.

[^v^Tinda wolf^v^]

I would assume it's in the transport Canada documentation, where's Dave? :lol:

[elkhunter11]

I would trust a grade 8 bolt over a cheap hitch pin from Princess Auto.

[Au revoir, Gopher]

used to have a shaft PTO driven water truck that had a shear flange on it. We used grade 5 bolts specifically for this as grade 8 would shear and snap easy while the 5's would absorb shock and last. Get a proper pin and your insurance company will have no reason to sue in the unlikely even of a failure

When I was a kid, I used a bolt in place of a proper shear pin once. And only once. It was on a New Holland PTO driven baler, I broke the last shear pin and the closest place to buy more was 30 miles away. I decide to substitute a bolt in hopes of getting the field done that day. When a shear pin breaks, it breaks cleanly and the two pieces just fall out, when the bolt broke, it bent and the two pieces were firmly wedged in their respective holes. By the time I got the broken pieces out, I had learned my lesson: use the proper shear pin!

ARG

[bpoppa85]

Agreed.
Unless the OP has free bolts and nothing but time....

Bingo!

[double gun]

I'd trust a Grade 8 bolt over a cheap Princess Auto/Cdn Tire/Walmart hitch pin any day.

I'm sure some of them are mild steel from the deformation I've seen.

I would trust a grade 8 bolt over a cheap hitch pin from Princess Auto.

X3

[oilngas]

IGS; I believe it is at least a City of Calgary bylaw, in addition it's just a nice thing to do that will inhibit klutzes like myself from walking into the hitch.

I know from person experience the shin bark pain is directly inverse proportional to the attention I am paying to where I'm walking!!!

[^v^Tinda wolf^v^]

My hitch must be removed when parking my truck in the garage. Don't ask me how I know that :medium-smiley-035:

[ctd]

Grade 8 bolt is not designed for shear force. When they say (approximately 60%of its tensile) it means they do not test for it and it is not rated for it. This does not mean it won't do the job, it means If your pin breaks and te trailer causes damage your insurance will walk away laughing.

When you buy a hitch pin they should have rating on the package saying how.many lbs it's good for. There are some pins with stamped ratings but very few do.
It costs money to stamp pins.

Argue with a guy who use to fix Aircraft in metallurgy and bolt fastness. Some bolts are designed for shear but they cost more then a few cents at the local bolt store.

Once you modify a bolt in any way ie cut the threads off drill a pin hole etc the bolt is no longer carries any rating unless the bolt was specifically designed to be modified. Again you don't pay a few cents for them and pick them up at the local hardware store.

Will a grade 8 work yup, will a grade 5 work yup. The five is a better bolt based on metallurgy and anti shearing abilities.

[RavYak]

Grade 8 bolt is not designed for shear force.

Bolts aren't designed for direct shear(they are designed to take shear via a compressed joint though) simply because of the threads... A bolt with no threads is the same as a pin which is designed for shear...

Many pins are hardened to much higher levels then grade 8 bolts.

As for your comment regarding the modification of bolt or any hardened metal for that mater. Hardened steel is cut all the time without significantly affecting its qualities. Yes if done improperly it can be an issue but considering the OP a) did not introduce excessive heat near the load bearing points of the pin and b) looks to have used a hacksaw or bandsaw which would not have introduced much heat it is fine.

If you are involved in metallurgy and aircraft fasteners you already know all this though.

I do see how using any sort of modified bolt on an aircraft would be considered a huge liability but there is nowhere near that liability in this situation.

The only way a pin like this would ever be an issue in an insurance case is if the pin breaking is what caused the accident. First they need to prove the pin was the cause and they would have to find the remainders of the bolt in order to prove a modified bolt was used. In the extremely off chances that this was to happen then the recovered bolt would prove it was grade 8 and that only unthreaded portions were used. At that point any decent lawyer should be able to get the proof required to prove that the modified pin was stronger then the standard hitch pins you buy from Canadian Tire, Walmart etc. At very worst case the OP pays a 3rd party to test bolts modified in the same way versus standard hitch pins, the bolt will be stronger.

[silver]

To me, I would use the bolt to get home. At the first opportunity I would use a proper hitch pin. Not because it would be better, but because of the liability. I would still keep the bolt around for emergencies.

[elkdump]

That's no fun :)

On another note,
A person can receive an infraction for leaving your hitch in place while not being connected to a load. :scared0018:

I can see a nylock not being sufficient enough for transport Canada anymore and being replaced with the stover nut, I wasn't aware it was code though :thinking-006:

A nylock is good for a first use application and can still be reused as long as it wasn't installed with a numatic air tool although the preferred choice is to discard it and use a new one. I feel much better using stover nuts for most things when I installed bolts in the past. Some areas the stover nut has been required by code for several years on major tie down points such as mounting a pintle hitch on a gravel truck etc.

The problem using a threaded bolt that is needed for an application such as a bumper hitch is the length of meterial before the threads start. Most often on a standard bolt the unthreaded portion stays at one length until you get up into a 6 inch length bolt. It would work just fine for such an application but would look a little goofy. I didn't use the technical terms for defining a bolt but give me a break, it's been twenty years since I got my red seal :) and even then I don't recal if bolt identification was in the welding bible :thinking-006: besides knowing how to read the grade of bolt of coarse, that part I remember!

An " Easy-Up-Hitch-Step" is on tens of thousands of work and service trucks all across NorthAmerica , and they fit snugly into the hitch receiver of the vehicle ,
So these would be Ticketed also ? Give me a break :sHa_sarcasticlol:

[^v^Tinda wolf^v^]

An " Easy-Up-Hitch-Step" is on tens of thousands of work and service trucks all across NorthAmerica , and they fit snugly into the hitch receiver of the vehicle ,
So these would be Ticketed also ? Give me a break :sHa_sarcasticlol:

I'm not disagreeing with you but I'm certain I heard it on the radio a couple years back after someone was killed by a hitch flying down the highway. I'm positive I heard that correctly...but I'm open to being proven wrong :bad_boys_20:

[elkdump]

I'm not disagreeing with you but I'm certain I heard it on the radio a couple years back after someone was killed by a hitch flying down the highway. I'm positive I heard that correctly...but I'm open to being proven wrong :bad_boys_20:

My best friend was killed driving along the highway, in his driver seat of his car when a canoe came off of tourists motor home , and came thru his windshield ,

There is no cure for stupid , except birth control in many cases

Another friend and his wife were both crippled for life when a spare tire from under a semi trailer became dislodged and hit their Honda civic head on,
Both of them spent nearly a year in hospital with resulting permanent disabilities ,
The truck driver didn't even know it happened,,

Again, no cure for stupid

[couleefolk]

So, it sounds like there may be a lot of folks having used "bolts" instead of legal pins. If this is the case, one would only have to check lawsuits in such instances, if they even exist, and see what the details are that a bolt actually failed, and how they came about their findings. If we had a lawyer that could find all these lawsuits and provide us with the findings from these cases, we would all have to quit guessing a whole lot, but what fun would that be?

[bpoppa85]

So, it sounds like there may be a lot of folks having used "bolts" instead of legal pins. If this is the case, one would only have to check lawsuits in such instances, if they even exist, and see what the details are that a bolt actually failed, and how they came about their findings. If we had a lawyer that could find all these lawsuits and provide us with the findings from these cases, we would all have to quit guessing a whole lot, but what fun would that be?

Sounds like a lot of work. I'll just use the pin. :scared0018:

[BobNewton]

Sounds like a lot of work. I'll just use the pin. :scared0018:

Smartest post in the thread.

Why do a ton of research to find out if there is a alternative to a system in which needs no improvement.

[roger]

Re: hitch in place.
The only thing I can guess it being ticket worthy is if it stuck more than the length past the vehicle which would require a flagging or light.

[Bushleague]

Grade 8 bolts are higher strength then the average hitch pin. If you were using it with the threaded portion I would have hesitations as you would have stress concentrations that over time could fail due to fatigue but since you used the solid portion of the bolt your pin is stronger then your standard hitch pin and you are fine. The only slight weakness is where you ground the protective zinc coating off the bolt as this area will now rust over time.

As for using grade 8 material for pins anyone thinking it is unsafe should research grade 8 hitch pins which are commonly used as higher strength pins in agricultural equipment for an example.

This is a common misconception, a grade 8 bolt's strength is measured in tensile strength... a straight pull through its length. I don't even know what the shear strength is, I'm sure this rating is out there somewhere but even being a journeyman Millwright I have never seen it.

I do know that the shear strength is lower on a grade 8 than it is on a grade 5 though. Have seen this multiple times... as tensile strength goes up the material always gets more brittle... therefore less tough and more succeptable to breakage under shock loads. If you want I could rattle off multiple instances where I have personally seen going up to a higher grade of bolt resulting in a bolts shearing off repeatedly... I would not risk it myself. With no actual rating you can get erratic, and unexpected results.

[elkhunter11]

http://tinelok.com/grade-5-vs-grade-8-fasteners/

Let’s look at an example of where grade 5 and grade 8 bolts are subjected to single shear loads (winch plate reference).

Using a .250-inch diameter grade 8 fastener gives you the following shear capability:

A = Cross-sectional area of the fastener size (since bolt bodies/shanks have circular cross-sections, use area of a circle) = Pi x r2 where R (radius) = .250/2 = .125, therefore A = Pi x (.125)2 = .0491 square inches (in2)
Capability in shear = 91,000 lbs / in2 x .0491 in2 = 4468 lbs

Using the same .250-inch diameter grade 5 fastener results in the following:
Capability in shear = 75,000 lbs / in2 x .0491 in2 = 3683 lbs

So contrary to what some people are posting, a grade 8 bolt is stronger in shear than a grade 5 bolt.

http://www.nucor-fastener.com/files/pdfs/techdatasheets/tds_013_shear_strength.pdf

Look at the chart and you will see that the grade 8 bolt is stronger in shear.

As to grade 8 bolts being so brittle.

https://www.youtube.com/watch?v=FVndKEtazNg

[Bushleague]

http://tinelok.com/grade-5-vs-grade-8-fasteners/



So contrary to what some people are posting, a grade 8 bolt is stronger in shear than a grade 5 bolt.

http://www.nucor-fastener.com/files/pdfs/techdatasheets/tds_013_shear_strength.pdf

Look at the chart and you will see that the grade 8 bolt is stronger in shear.

As to grade 8 bolts being so brittle.

https://www.youtube.com/watch?v=FVndKEtazNg

Yes... I looked it up today at work and you are right, but there is far more to it than that number. There is toughness, fatigue strength, elasticisity... all of these have to do with load reversals and shock loading... all factors that come into play with towing a trailer.

A while back I bent the stock bolts that hold the peg onto my dirtbike, I replaced them with grade 8 bolts and they broke within one season, this time I drilled out the holes to a larger size and the grade 8's once again broke within a season. The stock bolts which are grade 5's and also 2mm smaller diameter have never broken on the other peg in 5 years, I replaced the larger bolts with grade 5 and they have lasted two years now.

At the veneer plant where I work we run grade 5 bolts on our charger spindles, on one spindle the threads got buggered so we drilled and tapped to a bigger size, since it was an odd size we used grade 8 bolts for awhile as we didn't have grade 5's. Once again, the larger diameter grade 8's only gave a fraction of the life of the smaller diameter grade 5's on the other spindle. In one year we had the larger grade 8 bolts shear at least a half dozen times while I cant even remember the last time we had to look at the other spindles. Eventually we got right bolts and the problems disappeared.

Every machine hub I've ever seen comes with grade 5 hardware, barker knives and clipper toggles, pretty much anything else subject to highly dynamic loads also is supplied with grade 5 bolts. It is illegal to use a grade 8 or a grade 5 bolt in a rigging shackle because they simply are not designed to withstand these types of loads, roughly the same type of loading as a hitch pin but generally with less shock loading.

I've got a welding ticket and a millwright ticket which means I had to delve into metallurgy twice. I aced both courses in their entirety which means nothing in the real world, but it does mean I know my theory, and I have hundreds of thousands of hours in real world experience working on equipment that has failed spectacularly.... my point? I at least have some idea as to what properties you are actually need in a hitch pin, and I've come to feel that grade 8 bolts are not ideal for this. I strongly suspect most of the guys here claiming that its a good idea don't even know what properties they are looking for, let alone the limitations of a grade 8 bolt in this regard.

[ctd]

Yes... I looked it up today at work and you are right, but there is far more to it than that number. There is toughness, fatigue strength, elasticisity... all of these have to do with load reversals and shock loading... all factors that come into play with towing a trailer.

A while back I bent the stock bolts that hold the peg onto my dirtbike, I replaced them with grade 8 bolts and they broke within one season, this time I drilled out the holes to a larger size and the grade 8's once again broke within a season. The stock bolts which are grade 5's and also 2mm smaller diameter have never broken on the other peg in 5 years, I replaced the larger bolts with grade 5 and they have lasted two years now.

At the veneer plant where I work we run grade 5 bolts on our charger spindles, on one spindle the threads got buggered so we drilled and tapped to a bigger size, since it was an odd size we used grade 8 bolts for awhile as we didn't have grade 5's. Once again, the larger diameter grade 8's only gave a fraction of the life of the smaller diameter grade 5's on the other spindle. In one year we had the larger grade 8 bolts shear at least a half dozen times while I cant even remember the last time we had to look at the other spindles. Eventually we got right bolts and the problems disappeared.

Every machine hub I've ever seen comes with grade 5 hardware, barker knives and clipper toggles, pretty much anything else subject to highly dynamic loads also is supplied with grade 5 bolts. It is illegal to use a grade 8 or a grade 5 bolt in a rigging shackle because they simply are not designed to withstand these types of loads, roughly the same type of loading as a hitch pin but generally with less shock loading.

I've got a welding ticket and a millwright ticket which means I had to delve into metallurgy twice. I aced both courses in their entirety which means nothing in the real world, but it does mean I know my theory, and I have hundreds of thousands of hours in real world experience working on equipment that has failed spectacularly.... my point? I at least have some idea as to what properties you are actually need in a hitch pin, and I've come to feel that grade 8 bolts are not ideal for this. I strongly suspect most of the guys here claiming that its a good idea don't even know what properties they are looking for, let alone the limitations of a grade 8 bolt in this regard.


Very well said and very true.

[Soulcousin]

Very well said and very true.

X2 I'm glad someone brought up the key property at play here: toughness. I would like to know what the charpy impact values are for the 5/8 grade 8, 5/8 gr 5, and 5/8 pin. Just on a lark I would also like to know how a pin of Chinese manufacture compares to an OEM spec type pin. I would hazard to say the pins would be tougher.

In reality as other posters have mentioned there are far more weak points in the system than ANY metallic "rod" stuffed in there, especially considering a close fit between the receiver/hitch body and a bore that hasn't been pounded oval allows the "rod" to behave in double shear and not have to encounter and compounding bending loads.

Also, IMO the test comparing the 1/4 gr 5 and gr 8 bolts is a bit misleading. To get the strength of the grade 8 it would be quenched, an I would suspect that due to small relative volume of metal in the small bolt it would through hard. I would suspect that say a charpy sample taken right at the core of 1" bolts would be very similar.

[elkhunter11]

Yes... I looked it up today at work and you are right, but there is far more to it than that number. There is toughness, fatigue strength, elasticisity... all of these have to do with load reversals and shock loading... all factors that come into play with towing a trailer.

A while back I bent the stock bolts that hold the peg onto my dirtbike, I replaced them with grade 8 bolts and they broke within one season, this time I drilled out the holes to a larger size and the grade 8's once again broke within a season. The stock bolts which are grade 5's and also 2mm smaller diameter have never broken on the other peg in 5 years, I replaced the larger bolts with grade 5 and they have lasted two years now.

At the veneer plant where I work we run grade 5 bolts on our charger spindles, on one spindle the threads got buggered so we drilled and tapped to a bigger size, since it was an odd size we used grade 8 bolts for awhile as we didn't have grade 5's. Once again, the larger diameter grade 8's only gave a fraction of the life of the smaller diameter grade 5's on the other spindle. In one year we had the larger grade 8 bolts shear at least a half dozen times while I cant even remember the last time we had to look at the other spindles. Eventually we got right bolts and the problems disappeared.

Every machine hub I've ever seen comes with grade 5 hardware, barker knives and clipper toggles, pretty much anything else subject to highly dynamic loads also is supplied with grade 5 bolts. It is illegal to use a grade 8 or a grade 5 bolt in a rigging shackle because they simply are not designed to withstand these types of loads, roughly the same type of loading as a hitch pin but generally with less shock loading.

I've got a welding ticket and a millwright ticket which means I had to delve into metallurgy twice. I aced both courses in their entirety which means nothing in the real world, but it does mean I know my theory, and I have hundreds of thousands of hours in real world experience working on equipment that has failed spectacularly.... my point? I at least have some idea as to what properties you are actually need in a hitch pin, and I've come to feel that grade 8 bolts are not ideal for this. I strongly suspect most of the guys here claiming that its a good idea don't even know what properties they are looking for, let alone the limitations of a grade 8 bolt in this regard.


So were the larger grade 8 bolts torqued to the proper specs for a grade 8 bolt of that size, or were they torqued to the same specs as the grade 5 bolts?
As to having personal experience in the field, I also hold a red seal millwright ticket, as well as being a CET in Mechanical Engineering Technology, where we spent a great deal of time studying materials, as well as statics and dynamics. I also worked on pumps, turbines, gearboxes etc for many years, and I worked with the reliability people to resolve reliability issues with the equipment, so I have experience in the field to go with my relevant education.

[CBintheNorth]

Yes... I looked it up today at work and you are right, but there is far more to it than that number. There is toughness, fatigue strength, elasticisity... all of these have to do with load reversals and shock loading... all factors that come into play with towing a trailer.

A while back I bent the stock bolts that hold the peg onto my dirtbike, I replaced them with grade 8 bolts and they broke within one season, this time I drilled out the holes to a larger size and the grade 8's once again broke within a season. The stock bolts which are grade 5's and also 2mm smaller diameter have never broken on the other peg in 5 years, I replaced the larger bolts with grade 5 and they have lasted two years now.

At the veneer plant where I work we run grade 5 bolts on our charger spindles, on one spindle the threads got buggered so we drilled and tapped to a bigger size, since it was an odd size we used grade 8 bolts for awhile as we didn't have grade 5's. Once again, the larger diameter grade 8's only gave a fraction of the life of the smaller diameter grade 5's on the other spindle. In one year we had the larger grade 8 bolts shear at least a half dozen times while I cant even remember the last time we had to look at the other spindles. Eventually we got right bolts and the problems disappeared.

Every machine hub I've ever seen comes with grade 5 hardware, barker knives and clipper toggles, pretty much anything else subject to highly dynamic loads also is supplied with grade 5 bolts. It is illegal to use a grade 8 or a grade 5 bolt in a rigging shackle because they simply are not designed to withstand these types of loads, roughly the same type of loading as a hitch pin but generally with less shock loading.

I've got a welding ticket and a millwright ticket which means I had to delve into metallurgy twice. I aced both courses in their entirety which means nothing in the real world, but it does mean I know my theory, and I have hundreds of thousands of hours in real world experience working on equipment that has failed spectacularly.... my point? I at least have some idea as to what properties you are actually need in a hitch pin, and I've come to feel that grade 8 bolts are not ideal for this. I strongly suspect most of the guys here claiming that its a good idea don't even know what properties they are looking for, let alone the limitations of a grade 8 bolt in this regard.

There is a huge difference between a high-strength alloy shackle bolt and a case-hardened hitch pin.


But I agree that most in this thread are 'winging it'.

Again, use the proper equipment for the job and life is boring. Boring is good.

[CBintheNorth]

So were the larger grade 8 bolts torqued to the proper specs for a grade 8 bolt of that size, or were they torqued to the same specs as the grade 5 bolts?
As to having personal experience in the field, I also hold a red seal millwright ticket, as well as being a CET in Mechanical Engineering Technology, where we spent a great deal of time studying materials, as well as statics and dynamics. I also worked on pumps, turbines, gearboxes etc for many years, and I worked with the reliability people to resolve reliability issues with the equipment, so I have experience in the field to go with my relevant education.

But do you have "hundreds of thousands of hours in real world experience"?:)

Sorry Bushleague, couldn't help it.

[ishootbambi]

Yes... I looked it up today at work and you are right, but there is far more to it than that number. There is toughness, fatigue strength, elasticisity... all of these have to do with load reversals and shock loading... all factors that come into play with towing a trailer.

A while back I bent the stock bolts that hold the peg onto my dirtbike, I replaced them with grade 8 bolts and they broke within one season, this time I drilled out the holes to a larger size and the grade 8's once again broke within a season. The stock bolts which are grade 5's and also 2mm smaller diameter have never broken on the other peg in 5 years, I replaced the larger bolts with grade 5 and they have lasted two years now.

At the veneer plant where I work we run grade 5 bolts on our charger spindles, on one spindle the threads got buggered so we drilled and tapped to a bigger size, since it was an odd size we used grade 8 bolts for awhile as we didn't have grade 5's. Once again, the larger diameter grade 8's only gave a fraction of the life of the smaller diameter grade 5's on the other spindle. In one year we had the larger grade 8 bolts shear at least a half dozen times while I cant even remember the last time we had to look at the other spindles. Eventually we got right bolts and the problems disappeared.

Every machine hub I've ever seen comes with grade 5 hardware, barker knives and clipper toggles, pretty much anything else subject to highly dynamic loads also is supplied with grade 5 bolts. It is illegal to use a grade 8 or a grade 5 bolt in a rigging shackle because they simply are not designed to withstand these types of loads, roughly the same type of loading as a hitch pin but generally with less shock loading.

I've got a welding ticket and a millwright ticket which means I had to delve into metallurgy twice. I aced both courses in their entirety which means nothing in the real world, but it does mean I know my theory, and I have hundreds of thousands of hours in real world experience working on equipment that has failed spectacularly.... my point? I at least have some idea as to what properties you are actually need in a hitch pin, and I've come to feel that grade 8 bolts are not ideal for this. I strongly suspect most of the guys here claiming that its a good idea don't even know what properties they are looking for, let alone the limitations of a grade 8 bolt in this regard.

The actual specs have been provided but you FEEL you know better? Okay....

I could tell you about my tickets and education but that doesn't change the facts either. Instead, heres a real world scenario for you. Ever see them tank trucks driving all over Alberta? You know, liquid hauling semi trucks with pumps attached to the back of the tractor unit? Those pumps have a safety device installed on the pump driveshaft that's called a SHEAR PIN. It's job is to break off in the event the operator does something stupid like engage the pump with valves closed. Guess what that shear pin is. Go ahead....guess.

Give up?

It's a Grade 5 standard bolt in 1/4 or 5/16 depending on pump size. Get caught with a Grade 8 in there against industry safety code and you will be fired and possibly subject to fines. That awful polluting energy industry takes that schit pretty serious. The consequences could result in a spill of crude oil, condensate, produced water etc. You can FEEL whatever you like....a Grade 8 lot has way more shear strength than a Grade 5. I watched a fluid hauler try pushing against a closed valve with a Grade 8 where a 5 belongs. He had a bad day and was looking for a new job at the end of it.

As to the OP....hitch pins are 5 bucks. Your bolt idea will work, but why would you?

[Arty]

I've got a welding ticket and a millwright ticket which means I had to delve into metallurgy twice. I aced both courses in their entirety which means nothing in the real world, but it does mean I know my theory, and I have hundreds of thousands of hours in real world experience working on equipment that has failed spectacularly.... my point? I at least have some idea as to what properties you are actually need in a hitch pin, and I've come to feel that grade 8 bolts are not ideal for this.[...]
So, with your tech ticket classes you should be able to give a step-wise systematic engineering explanation for what you think you're seeing then, right? Rather than just repeating old wive's tales still floating around in the field. Go on, have at 'er.

Yes... I looked it up today at work and you are right, but there is far more to it than that number. There is toughness, fatigue strength, elasticisity... all of these have to do with load reversals and shock loading... all factors that come into play with towing a trailer.

For most steels including med-carbon steels used in sae 5 and 8 bolts, you'll have a linear elastic region on a stress/strain (force/elongation) graph. Stretch the material a certain amount, and the force it pulls back with increases linearly. That's elasticity. It's also ductility, which stone or cast iron doesn't have much of. After any stretching or bending in that region, the material will return to its original dimension. Stretching it any more, and it won't go back. That's the yield point. The stress point there is the yield strength. Pull a little more and you get a maximum possible stretch-resistance force called the ultimate strength. Pull even more and the stress force on a sample drops back then the sample breaks. That's the breaking strength.

Tensile strength is a general term which can mean any of those three. You have to specify which one, AND you have to make sure any comparison uses the same definition for both. The main point made several times already in this thread is that class 5 will have gone beyond either its yield point force or ultimate point force before the class 8 leaves its elastic force limit. As both have significant elasticity, neither is brittle by definition.

As far as fatigue goes, a higher strength steel will have a higher fatigue limit [force] than a lower one, other things being equal. Steel samples are often tested and quoted with as many as tens of millions of cycles in order to get them to fail at all through fatigue.

Toughness is how much energy a material can absorb without breaking. That can be calculated by the area under the stress/strain graph mentioned above. If the curve is higher everything else being equal the material is tougher, such as grade 8 vs 5. Note the Charpy test (could be called shock loading) was developed to test the effect of temperature on steel toughness for ship plate. If there are Charpy tests around clearly showing that grade 8 material is inferior at similar temperatures due to shock loading, I'd sure be interested in seeing it.

And yes, I have done steels tensile and impact testing in the lab.


A while back I bent the stock bolts that hold the peg onto my dirtbike, I replaced them with grade 8 bolts [...]

At the veneer plant where I work we run grade 5 bolts on our charger spindles, [...] Eventually we got right bolts and the problems disappeared.

Every machine hub I've ever seen comes with grade 5 hardware, barker knives and clipper toggles, pretty much anything else subject to highly dynamic loads also is supplied with grade 5 bolts. It is illegal to use a grade 8 or a grade 5 bolt in a rigging shackle because they simply are not designed to withstand these types of loads, roughly the same type of loading as a hitch pin but generally with less shock loading.

Anecdotal observations under uncontrolled conditions can lead to a whole lot of false conclusions. Provision of grade 5 stuff for fittings instead of 8 by a supplier is almost always due to penny-pinching. And you know that using higher strength bolts often means needing to stress them with a higher torque so the whole joint works properly.

So far, we've seen absolutely nothing concrete indicating a grade 5 bolt behaves better than grade 8 in hitch loading or any other application where you don't want something to break. And even less which indicates that some cheap pin of unspecified properties and unknown source is magically better just because it has a keeper pin in it. Or that 'hitch' was printed on its retail walmart/cdntire bubble package.

An 'indication' means that tests and physical and chemical properties of the batch of material certified to be used in manufacturing, as well as performance of the finished project, are available for review. Just like imported pipe, vessel, and w-beam structural steel has to be. Or like the alloy used in cone bolts to hold on aircraft engines is.

[Bitumen Bullet]

....... And even less which indicates that some cheap pin of unspecified properties and unknown source is magically better just because it has a keeper pin in it. Or that 'hitch' was printed on its retail walmart/cdntire bubble package.

An 'indication' means that tests and physical and chemical properties of the batch of material certified to be used in manufacturing, as well as performance of the finished project, are available for review. Just like imported pipe, vessel, and w-beam structural steel has to be. Or like the alloy used in cone bolts to hold on aircraft engines is.

Seen more than enough counterfeits with all the correct stamps (not just bolts, all sorts of hardware and parts) that I no longer trust them even with paperwork, best to test.

An industrial mechanic at one company I worked for kicked off an internal investigation when he picked up a Grade 8 bolt and said it "felt" different. The grade 8 bolts were almost perfect copies and many had been put into use through out the company. Too bad Education, Training, and Experience are too expensive for most companies because that one Mech may have saved many major lawsuits.

Bottom line is if it's important best to test and keep the paperwork. Counterfeiting and parts swapping can happen anywhere along the chain, even after delivery if there is money to be had.

As for which bolt gets used where, all that info is in this thread.

[sanjuanworm]

So to sum things up, just go buy a hitch pin M'kay?

[Okotokian]

I'm no expert so can't vouch for strength. My position is that with something with a high safety risk, I'm going to use parts designed for the task. I'm not going to risk getting my %#$$ sued off to save $10. You KNOW that if your trailer comes off, the opposing counsel is going to focus on your "negligence". Heck, your own insurance company might focus on that too to get out of paying. Not worth the risk in my books. And if a part designed for the task breaks, perhaps YOU can sue that company, or at least pass along the liability.

[bpoppa85]

I aced both courses in their entirety which means nothing in the real world, but it does mean I know my theory, and I have hundreds of thousands of hours in real world experience working on equipment that has failed spectacularly.... my point?

I'm just a simple electrician. I have no knowledge in metallurgy and that is why i asked the original question. You bring, I believe, some valid arguments. I struggle however to take you seriously when you pose a well worded argument followed by "I have hundreds of thousands of hours of real world experience.." At a mere 100,000 hours at 2080 hours per year that's 48 years of experience. Maybe...but dougbtful. You didn't have to add that for effect. Just my opinion.

I'm no expert so can't vouch for strength. My position is that with something with a high safety risk, I'm going to use parts designed for the task. I'm not going to risk getting my %#$$ sued off to save $10. You KNOW that if your trailer comes off, the opposing counsel is going to focus on your "negligence". Heck, your own insurance company might focus on that too to get out of paying. Not worth the risk in my books. And if a part designed for the task breaks, perhaps YOU can sue that company, or at least pass along the liability.

Just to play devils advocate, not that i don't agree with you, If there was a catastrophic failure and the pin was to blame chances are that pin is long gone in the ditch somewhere and I or anyone in this hypothetical situation isn't going to say it was probably the homemade pin. Again...just devils advocate.

[CaberTosser]

Grade 8 is brittle. Grade 5 is a better option. The best option is a pin designed for the job.


If you think that's the case, try replacing the connecting rod bolts in your vehicles engine with grade 5 hardware and get back to me. I won't recommend conducting the test with road trips far from home.

[JustBen]

If you think that's the case, try replacing the connecting rod bolts in your vehicles engine with grade 5 hardware and get back to me. I won't recommend conducting the test with road trips far from home.

Don't worry - he's got a ring and a stamp.

[bb356]

Thoughts? I have a 5/8 x 6" grade 8 bolt that i have cut the threads off of and drilled a hole through the center for a hairpin cotter. Got me thinking though if it was a smart thing to use as a hitch pin or just not be cheap and go buy a new hitch pin. Is it safe to use the grade 8 bolt or is it better?

Thanks

Buy a hitch pin that conform's to today's standard's ... if what your pullin fly's off at least you don't have to explain to your insurance company that you didn't follow the rule's ...

[Rdamours]

I'd say go with what the engineers says. Sounds like this would get his thumbs up :) Grade 8 and Princess Auto so both camps should be happy. Chinese heat treated to equal of performance of grade 8 in broken English so my bad. Grade 8 hitch pins exist so conceivably that's a way to go. Here's a doc with lots of info other than just the grade of the bolt and other possible failure points. I'd be just as concerned about the rusted out bolts or hack weld jobs holding the receiver on the rusted frame.

http://www.princessauto.com/en/detail/7-8-x-6-1-2-in-grade-8-hitch-pin/A-p8622631e

https://www.extension.purdue.edu/extmedia/ppp/ppp-94.pdf

[Bergerboy]

If you think that's the case, try replacing the connecting rod bolts in your vehicles engine with grade 5 hardware and get back to me. I won't recommend conducting the test with road trips far from home.

Lol. Use the item designed for the job. You should know that with your trades.....um your trades....um.....hard hat sticker???

[HyperMOA]

Lol. Use the item designed for the job. You should know that with your trades.....um your trades....um.....hard hat sticker???

Not too sure what you are implying here. However, if you are saying what I think you are saying, I think its hilarious. I have a friend becoming an engineer and I get a phone call every week or two for this dumb tradesman to help him with his homework. When I began telling him about the processes of making austenite and its properties. Among many other such subjects; it really opened his eyes about how poor my education is.

[Bergerboy]

Not too sure what you are implying here. However, if you are saying what I think you are saying, I think its hilarious. I have a friend becoming an engineer and I get a phone call every week or two for this dumb tradesman to help him with his homework. When I began telling him about the processes of making austenite and its properties. Among many other such subjects; it really opened his eyes about how poor my education is.

Sounds like your bud has a long and difficult road ahead of him. Hopefully he keeps at it and is succesful.

[JB_AOL]

Is this seriously still going?

Buy the part designed for the use. HITCH PIN.. End of story..

Pretty sure it's only a couple bucks vs millions when you kill someone.