Receiver hitch for a deuce

[russ81]

Yes, cadmium, zinc electroplate, yellow zinc chromate, hot dipped galvaized, all plating works as a lubricate. I learned this lesson the hard way assembling a pedestal crane with 1" grade 9 bolts, and was busting them in two at only 75% torque load.

I ALWAYS lubricate hardware EXCEPT when using lock nuts. When using the lock nuts, either nylock, crimped, or castleated, you never want to use lubrication. The plating is enough lubricate, and lock nuts are a one-time use fastener.

When you get into the really technical aspect of hardware and fasteners the TYPE of lubrication makes a big difference. This info is really not important for use here, but just wanted to throw that out there.

The big thing is to use a lubricant that is compatable with the application. Use engine oil to lubricate bolts going internal of the engine, transmission fluid or grease that will be used in the transmission, ect... For external (frame, exhaust, lug nuts) nothing beats a good quality Never-Sieze. Lubricating hardware is a lot more important then most people realize, but none of it is more important then proper torquing, and the proper torquing technique.

 

[Albin]

Hey guys, I think we should do a little research into using the proper hardware for bolting up these hitches.

Grade "8" bolt is actualy TOO HARD, for this application. These bolts are good for an installation under constant stress load, but not for something that takes a "shock" load. Grade 8's are prone to cracking when this happens. What we should be using is an "A-325" bolt, which is a structural steel bolt. When properly torqued it is designed for applications that take both stress loads, and shock loads. That is why it is a Federal requirement for all steel structures to be built using this grade of fastener. These fasteners can be found at a company called Fastenal. If you get one of their catalogs they have a really great section that gives all the engineering data needed to find the correct fastener for what ever application you are using.

Just my . I deal with this stuff every day, and see what the effects are from using the improper hardware, and I don't want to see any one loosing a trailer because they used the wrong bolt.

I disagree with some of your points, as discussed below:

- Grade 8 bolts are not "too" hard, nor are they prone to failure due to "shock" loads. A g8 is more "brittle" than a g5, but only after it reaches yield. A g5 will bend to yield (i.e. permanent deformation - not good) and break well before a g8 will bend to yield, much less break. Look at the SAE J429 spec sheet in the paper linked below.

- Ford uses Class 10.9 bolts for attaching their Class V hitch to the frame of my '06 PSD. Same with Dodge on my '98 Ram, except that was a Class IV hitch. Class 10.9 is the metric equivalent to g8 bolts. Clearly, using g8 bolts and nuts for attaching a hitch to a frame is acceptable in the industry.

- A-325 bolts are ASTM structural bolts, they are neither designed for nor should be used in automobile/truck type applications; as noted in the OP's post, they are roughly equivalent to SAE J429 Grade 5. A-325 bolts and nuts are designed to be used in structural applications like bridges, buildings etc. As discussed above, g8 bolts are stronger and are clearly used in the automotive industry for use in that industry, not ASTM A-325 bolts.

For a good primer on fasteners that disputes and hopefully kills a lot of the myths about g8 bolts, read this paper here: Fastener Tech - The Nuts and Bolts of It

Another good source of fastener information is located here: Fastenal Tech Reference Guide



Al

 

[russ81]

I agree with you on several points, but I respectfully dissagree with you on most. I stand by my initial write up. Grade 8 bolts ARE prone to failure due to shock loading at a higher rate then A-325's, where as A-325's are specifically designed for shock loading.
I have worked for companies such as Toyota, Ford, GM, and Honda building and re-building their manufacuring plant, and can say with out question they are always behind in industrial standards. They look for cheap ways to assemble parts that will last until the warrenty ends. NO truck today is manufactured to withstand continuous rough service. Only for occasional use. The heavy industry that I work in sees continuous rough service, and thus must design and engineer every part to work 24 hours a day 365 days a year under the most adverse conditions with the most deadly chemical combinations ever created by mankind.
You all do what you want, but I will trust the engineering of heavy industry over that of the automotive industry.

 

[Jake0147]

FWIW:

I just barely installed a two inch on a new (to me) F-250. The hitch is rated for 15,000 pounds. (The truck, not quite so much so...) But the 15,000 pound hitch came with grade five bolts. I thought this odd, and discussed it with the fellow for a minute. (He runs a trailer sales business, not a tech service...) But, he said he'd noticed that and asked the fellow who installes his hitches. The guy says yeah, I don't know why but the same brand hitch for the same truck in 6,000 pounds comes with grade 8 bolts...

Curious to say the least. Now that he/they were curious too, they poled at at least fifteen hardware kits, several brands, and found hit and miss in six thousand pound range, some had grade five, some had grade eight, INCLUDING one hitch that the installer fellow believes to be the identical hitch under different part numbers, but with a different grade of hardware and different shaped spacer washers in the kit. Without fail, there was ONLY grade five off the shelf bolts in any of the 10K plus hitches.

Further curiousoty found that the gooseneck hitch lower frame that came with my truck uses grade 5 hardware to bolt it to the truck frame, I don't have the ball to go on it, just a gaping hole where it used to be, but the installer once again showing off his vast knowledge of his hitch installing trade was sure they were grade eight. They didn't have one, but the installer guy said proceeded to look up an old instruction sheet in his round file from a similar one he'd installed a day prior to verify, and they were carriage bolts, no grade specified, but they were described as "yellow coated".

Scraping the rust off of the hitch on my soon to be gone F150, I found grade eight hardware.

I dunno the specifics or the why's but somewhere there's an engineer or two that doesn't like grade eight bolts on trailer hitches, yet sometimes they do like them??? One day I'll know everything and I'll be able to answer stuff like this. I don't doubt that either would be fine and overkill answers are out there, but I can't help but wonder just what the difference is that the engineers are seeing from one application to another in a different but so similar application, and seemingly "retrograding" the hardware as the hitch capacity goes up.

If/when I put a hitch on my deuce, I'm using whatever comes in the kit. I know you guys crossed this bridge a long time ago, but I'm still wishing for one that when I pulled the pin out I could remove the whole reciever.

 

[toddm]

I built mine a couple of weeks ago, it is 24.25 inches from the ground to the bottom of the receiver hole and I dropped the hitch only 7 inches from the frame. It probably would have been easier to just go out and buy a hitch, but I was determined to build one myself. Thanks Todd

 

[russ81]

Jake,
A grade 5 bolt is an acceptable bolt for a hitch if it is large enough in diameter. The advantage of a grade 5 over a grade 8 is it's ability to stretch before it breaks. It is almost like comparing apples to oranges when your talking bolt grades and diameters. You have to ask yourself what the application is. Don't quote me on this it is just an example, but it is like comparing a 3/8" grade 8 to a 1/2" grade 5. In a high stress application, like a head bolt, the 3/8" grade 8 will out perform the 1/2" grade 5 where there is constant tension. The 1/2" grade 5 would be the better bolt of choice if I was putting it in a brush hog where I was experiencing bouncing or jolting. I have actually done this with a brush hog. Grade 8 bolts kept failing, so I installed A-325's in the same size. That was about 10 years ago, and they are still working fine.
A bolt is designed to work like a coil spring. If you have a stiff coil spring it can take a larger load, but will break if it is shocked while under load. A weaker coil spring can not take as large of a load, but since it is softer it can absorbe a shock load easier.

 

[Jake0147]

I didn't measure them all, but I'm pretty confident that every bolt we looked at was a half inch bolt. I see a lot of bolts in the course of a day, I'm fairly confident in that.

EDIT-
The gooseneck hitch does use larger bolts. But the lower frame is good for 20,000 lbs, and the bolts (and the joint) carry the weight very differently. All the ones we looked at inside were two inch tag-along recievers of varying capacity and for various applicatioins. You're quite right that size matters as much as (sometimes more than) the grade of the bolt.

 

[russ81]

Jake,
With the gooseneck the bolts almost always only in shear. They are not holding any weight, since the hitch frame is setting directly on the truck frame. Where as the receiver hitch is usually mounted under the frame hanging off of the bolts, so the tongue weight is then transfered to bolts in a tension along with also being in shear.

 

[Jake0147]

Yes, on the gooseneck the ball mount sits directly on a frame, but then that "lower frame" does not sit on the truck frame, it bolts to the outside of the truck frame, so the bolts are horizontal. Those are always in shear no matter what you do. But there again, they're bigger. I guess that's kind of an aside for me, like you said with the apples to oranges. My curiosity was struck by the fact that within his brands of hitches, within the tagalong ones that all mount the same way, the manufacturer's choice of bolt seemed counterintuitive. Pretty much questioning what property of the bolt are they after if it's not the strength of the bolt. Considering that the hitch shouldn't move to shear the bolt anyhow. it seems that the clamping force is what holds the hitch in place, so the bolts should all only ever see tension and never any shear, so there really shouldn't be any other properties in play in the equation.
Sometimes I think that I think too much.

 

[littlebob]

I'm no engineer and have learned alot from this post, but on a hitch where none of may recheck the tourqe as often as we should would be better off with the stronger bolt(G or the G5 that may stretch and come loose? Don't know just asking.

littlebob

 

[Shizzlemah]

Jake,
With the gooseneck the bolts almost always only in shear. They are not holding any weight, since the hitch frame is setting directly on the truck frame. Where as the receiver hitch is usually mounted under the frame hanging off of the bolts, so the tongue weight is then transfered to bolts in a tension along with also being in shear.

Any bolt that is in shear is not properly torqued. A properly torqued botl is ONLY in tension. That tension provides clamping between two surfaces, and then it's friction between those surfaces.

There is no difference in bolt loading if the hitch is over or under the frame (assuming the bolts are properly torqued)

 

[Albin]

I agree with you on several points, but I respectfully dissagree with you on most. I stand by my initial write up. Grade 8 bolts ARE prone to failure due to shock loading at a higher rate then A-325's, where as A-325's are specifically designed for shock loading.
I have worked for companies such as Toyota, Ford, GM, and Honda building and re-building their manufacuring plant, and can say with out question they are always behind in industrial standards. They look for cheap ways to assemble parts that will last until the warrenty ends. NO truck today is manufactured to withstand continuous rough service. Only for occasional use. The heavy industry that I work in sees continuous rough service, and thus must design and engineer every part to work 24 hours a day 365 days a year under the most adverse conditions with the most deadly chemical combinations ever created by mankind.
You all do what you want, but I will trust the engineering of heavy industry over that of the automotive industry.

No offense but the statement in bold above is an excellent example of how myths get started. And like a lot of your statements on Grade 8 vs. Grade 5 (& A325) it is a myth.

Here's why:

ASTM is the American Society of Testing Materials, the premier standards organization for most industrial products and services in the US (and most of the rest of the world), including but not limited to fasteners. ASTM specification A325 is the governing specification for all A325 fasteners manufactured and sold throughout the US and the rest of the world.

The ASTM A325 spec is an 8 page specification. Section 4 deals with Materials and Manufacture; Section 5 deals with Chemical Composition and Section 6 deals with Mechanical Properties (hardness, tensile strength etc.) and Section 7 deals with dimensions. The rest of the spec is scope and Quality Assurance language.

No where in the ASTM A325 specification is the word “shock” used.

In addition, the scope of ASTM F606, titled “Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets” covers the establishment of procedures for conducting tests to determine the mechanical properties of
externally and internally threaded fasteners, washers, direct tension indicators, and rivets. In other words, if a fastener manufacturer wants to build and sell ASTM A325 (or any other ASTM-spec’d fastener) these are the ASTM tests methods to be used to certify those fasteners to the physical and mechanical properties required by the ASTM fastener spec.

The word “shock” is not used in F606 either. In other words, in regards to fastener, ASTM neither lists it as a requirement nor has a test to test for it.

So please feel free to back up your statement that “A-325's are specifically designed for shock loading”, because it’s not supported by the applicable ASTM specifications.

Unfortunately, the ASTM specs are not in the public domain. However, any industrial company with a decent tech library can get copies like I did. Or you can go to the public library and ask for a copy of “Fastener Standards” published by the Industrial Fastener Institute; in the Sixth Edition, ASTM spec A325 is on page E-11.

Since you alluded to your background, I'll give some of mine in return:

+28 years as an engineer for a very small aerospace and defense contractor. We're into attack helicopters, fighter jets, airborne warning and control, ballistic missile defense, space stations, military, commercial and intelligence satellites, and a bunch of other odds and ends that I don't recall at the moment. Oh, and we also have a small side business designing and building commercial airplanes, but those guys are taking a break right now.

Most of my experience with fasteners have to do with MS, NAS, NASA and MSFC spec'd fasteners plus certain proprietary fasteners (mostly space related).


With respect, I look forward to your reply.

Al

 

[ajg6989]

Standard class 3 lined up used grade 8 bolts had to drill the last 2 holes but the other 4 lined up perfectly. Used a 6" drop hitch. For the front I welded a plate behind the bumper drilled out another plate so I can adjust the hieght and I have a combo pintle and ball mounted oon the front for when I want to push a trailer into place. It is alot easier then trying to back one up with the van body blocking your view.

 

[russ81]

Albin,
The "myths" as you like to call them, maybe myths in the automotive industry where your dealing with a vehicle that weighs 6,000 - 8,000 lb's., but in heavy industry where your dealing with loads of several hundred tons of force these "myths" become reality very quickly.
You are correct in one thing. No where is the term "shock loading" used. It is a term that I use so people that don't understand the dynamic forces at work can understand the points that I am trying to make. The correct engineering term would be "repetitive loading cycles." This is the exact forces at work while pulling a trailer during accerleration and breaking.
Below is a link to a very common situation where an individual asked if a grade 8 bolt was a proper substitiution in a joint that previously had A-325 bolts.
http://www.aisc.org/MSCTemplate.cfm...tomSource/Faq/SteelInterchange.cfm&FaqID=1990
The engineers answer back was an absolute NO. The engineer from Stone & Webster, a company that I have worked for before, stated basically that the A-325 will deform and stretch, his words, during this "repetitive loading cycles" before yielding. A-325 bolts are designed to work like a coil spring. They will come and go as needed with out breaking, as long as those cycles do not take the bolt past it's designed yield. The grade 8 bolt has tremendous clamping force, but does not have the ability to enlongate or deform before yielding. Nor was it designed for use in a "repetitive loading cycle". It is designed for use under constant loading.

 

[Jake0147]

Albin,
The grade 8 bolt has tremendous clamping force, but does not have the ability to enlongate or deform before yielding. Nor was it designed for use in a "repetitive loading cycle". It is designed for use under constant loading.

Question:

If the bolt selected for a "standard" application (bolting two stationary pieces together such as the hitches here...) is of a proper size, and properly torqued that would mean that the opposing forces from each side of the joint would never exceed the preload. I'm straining my brain but I'm not seeing any load cycling until the preload is exceeded. Am I missing something?

 

[docfarmall]

glad someone posted these good job guys

 

[snocrazy]

grade 8 works great.