Off Roading Forums banner
1 - 20 of 30 Posts
G

·
Discussion Starter · #1 ·
I remember this being discussed before, but can't find it.
When installing tow hooks, which is better?
I used Grade 5 because the Grade 8 have a higher tinsil (can't spell) strength and will shear before they'll give a little.
Am I on target here, or am I suffering from a brain fart here?
Any web sites with info would be greatly appreciated.

_____________________
John
95.5 YJ with "stuff"
http://SonsofThunder4x4.com
 
G

·
Discussion Starter · #2 ·
Yes Grade 5 has a greater shear strength than Grade 8. You can go to this link and it should tell you about fasteners. Then go to online Calculators.
http://Fastenal
 

·
Official Curmudgeon
Joined
·
4,707 Posts
That's BS. Grade 8 has higher sheer strength than grade 5, I looked it up the last time this came up.
Of course if it were me, I'd use stainless.


 
G

·
Discussion Starter · #6 ·
I know that the Grade 8 has the higher shear strength. What I wanted to know is this...

Is that really a good thing? Is it better to have some give before it snaps, or no give and more resistance to snapping? Keep in mind that this is a tow hook. How many times do these get used for a sudden "violent" pull as opposed to a slow steady pull?
Sure it's easy to sit here and say that all recovery should be the slow and easy kind, but in the mud it's another story.

_____________________
John
95.5 YJ with "stuff"
http://SonsofThunder4x4.com
 
G

·
Discussion Starter · #7 ·
If it were me I would use grade 8. The grade 5 may stretch a little before it fails, but even if it doesn't fail the force required to break it the next time will be lower. The grade 8 will be unaffected by forces required to stretch a grade 5, and the grade 5 will fail before the grade 8. Therefore the grade 8 will provide better service. The only problem is that when a grade 8 does fail it is a catastrophic failure. Meaning it holds to a point, beyond that point it fails completely. For this reason you should always have something attached to either end of your tow strap or to the middle and end of your winch cable that will act as a parachute to slow down the flying ends. The upside to this catastrophic failure is that there is no false sense of security the next time like there is with a fatigued grade 5.

My other car is a BULLDOZER
 
G

·
Discussion Starter · #9 ·
One more thing to add here -
If you put in a pair of Grade 8, 1/2" bolts for each hook, the failure will probably be the frame connections first. I wouldn't bet the farm on this, but I would bet the ranch house. There is nothing on the frame ends that is the match of Grade 8.
sln

 

·
Registered
Joined
·
6,870 Posts
If you intend to actually use the hook often, and it's going to be real yanking on them instead of just a gentle pull,

Use Grade 8 bolts, as large as you can get through the holes.

Use thick, hardened washers, again grade 8, as large as you can fit. If the washers need to be ground on to make them fit, do it.
(The washers will help spread the load out on the frame.)

Use the Nylon type self locking nuts instead of lock washers. Lock washers will keep any nut from compressing the attached pieces evenly.
There is no heat in this situation, so nylon type lock nuts will hold just fine.

The hook side shouldn't need washers unless the backing material for the hook is thin enough that it will flex.
Make sure the hook side holes are 'spot faced' 90 degrees to the hole, or use washers ground at the angle of the facing.
Some of those hooks are forged with an angled base where the bolt goes through. You will need to grind that facing flat, or use an angled washer to get a straight through hole with a flat, (perpendicular) facing for the bolt shoulder to rest on.
If it stays at an angle, the bolt head may break off.

(don't use a hook you can find the forging line in! If it has a little thin line in it where the mold cam apart, throw it away! It's cast, and is dangerous for anything but car shows, anything made out of the country would be suspect)

Seems like a lot for just bolting two pieces of metal together...
We used to use a lot of these kinds of hook when I was young, we moved HOUSES!
When a house could potentially fall on you literally, you tend to pay attention to the little stuff...
(Ever seen what happens to a wire rope when you are moving 650 tons and a hook lets go?.... It isn't pretty!)

Later folks, hope this helped, Aaron.

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
 

·
Registered
Joined
·
6,394 Posts
/wwwthreads_images/icons/tongue.gif I think that this is a Grade 5 application, since Grade 8 is Anti-Shear, and Grade 5 is Anti-Stretch, Anti-Shear. Grade 5 will not take as much direct shear, but it will bend around a corner and still hold because of a little better ductility. Boy, did Team Rush hit it right on about "supposedly" forged hooks from across the pond Sometimes you have to look real close, but if it ain't forged, don't use it. My moonguys/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/wink.gif are here in the ofice and sort of in the way, but they were wondering if all who read this post are really clear about forgings? And why they are good? If you aren't completely clear on forging, just say so and we'll discuss it just a bit. It's kind of important./wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.
 
G

·
Discussion Starter · #12 ·
I am sorry for the incorrect information that I gave in an previous post. That is why I like this board soooo much. I was going on info when I built pallet racks for a company and they said use grade 5 for the "shear" strength, But I used grade 8. The only reason I used grade 8 was because these are the ones of correct size and of the highest quality that I could find at the time in stock. I trust TR's opinions and his insight.

The best part of this board is that I can be wrong, then corrected and still no flames.

I stand corrected!!!!!

I Learn something new everday. If I stop learning, I must be dead.

Lunatic
From the land time forgot Home Page
 
G

·
Discussion Starter · #13 ·
the other thing to consider is going to the bone yard and buying oem tow hooks. they are inexpensive, and most are designed to bend if the capacity is exceded rather than break, this decreases the chance of a high velocity five pound projectile. most are mounted via grade 5 hardware for the same reason. just make sure you "go large" and you will be better off.

now my personal preference is to use a 3/4in clevice ("d" ring) and a closed loop mounting. they are easy to come by, and much safer do to the fully enclosed attachment. the new ford super duty use a perfectly good tow loop that would work great for this.

just a little food for thought.

dan
Good things come to those who do research!!
 

·
Registered
Joined
·
6,870 Posts
I personally think unless you are going to lift the jeep with people on board, Grade 5 or 8 would both work.
I said Grade 8 because there shouldn't be anywhere to bend the bolt to if it's secured solidly, and the grade 8 is a little more resistant to pull apart and shear loads...

Getting a hook that is forged is more important that securing it with grade 5 or 8 bolts!

I see guys getting pulled out all the time with people standing in the 'Whip' zone.
The 'Whip' zone is the area where the chain, rope or cable can 'Whip' to if something lets go.

I got to the scene about five minutes after one of the trucking company employees got 'Whipped' one time.
The cable cut both legs off, one just below the knee, the other right through the knee joint.
They were trying to pull a loaded rock truck out of the mud, and the hook broke off of the truck.
A 1-1/2" wire rope whipped around an cut the guy in half at the knees.
It wasn't pretty, it wasn't clean, and he damn near died of blood loss. It strung out the muscles for about three feet before tearing the legs completely off.
It was also completely unnessary. All he had to do was back up twenty feet.
--------------------------------------

I was working on the same job site as a guy that had his neck broke by a nylon choker strap. (I wasn't there at the time, but I helped clean up and look for pieces afterwards.)
The hook let go, and the strap caught him in the side of the neck, and broke his neck.
The hook pieces disengaged from the choker before it got to him, and one of them went through a truck door and imbedded it's self in the dash, we never found the other part of the hook. Both of those could have killed other people.
The guy that got hit is wheel chair bound now, and can't even wipe his own butt...
-------------------------------

Not to be changing the subject, but the brother of a good friend of mine was just killed in the coal mines around here last week.
He and two others were removing a track from a D-11-N, and he was holding the bar, (via a fan belt and 2X4 arrangement) while one of the other guys stood on the track and hit the bar with a sledge hammer to push one of the link pins out.

They had done this same operation hundreds of times, so it was old hat to them.
The head of the bar was mushroomed, and one of the sharp, jagged slivers cam off, about the size of a .22 bullet, and tore through the Aorta on the top of the heart.
He was dead before they could find out what was wrong with him...

He was 32 years old, had two kids, and was one hell of a nice guy.
He had a large amount of insurance, but that doesn't make up for kids growing up with no father, or the pain that family feels.
---------------------------------

Please grind off the mushroom on your punches and chisels folks.
It may not kill you, but it sure could destroy an eye, or cause you to have major surgery to remove it...
(and if you have never had chest surgery, believe me, you DO NOT want to meet the RIB SPREADERS...)






If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
 

·
Registered
Joined
·
418 Posts
Maybe I can clarify (or complicate?) things further.

In tension or shear, grade 8 bolts are stronger than grade 5. Period.

For a given load, any steel bolt (grade 8 and grade 5 or grade anything) will stretch the same amount, up to its yield strength (also known as its elastic limit). Remove the load, and it "unstretches" back to its original length, i.e. there will be no permanent stretch (like a spring). For a grade 8 bolt, this load (and corresponding stretch) is greater than a lower grade.

Above the yield strength, the stretch increases dramatically with very small increases in load, until the ultimate load is reached. Again, the ultimate load is higher for a grade 8 bolt than it is for a grade 5. Furthermore, if you stretch a bolt beyond its yield limit, it will not return to its original length (like a spring you've stretched out of shape).

Softer steels will stretch more than harder ones before they break, but the actual load at the break point will still be much lower for the soft steel.

I used tension examples, but shear behaves in much the same way.

Then there's fatigue strength. Bend a piece of metal back and forth a bunch of times; it may not break right at first, but it will break eventually. For any given metal, there is a fatigue limit, which is lower than the ultimate load. Below the fatigue limit, bend it as many times as you want and it won't break; above that, it will eventually break. Again, in general, the higher the ultimate strength, the higher the fatigue limit.

Finally there's impact loading. This is tested by notching a steel bar and hitting it with a hammer (very precisely, of course). This is the one case where a softer steel might do better, as harder materials tend to be more brittle. However, for most of our applications it's not that important (unless you're running a snowplow or trying to snatch a stuck Jeep out with a chain instead of an elastic nylon strap), as the suspension tends to damp out and spread loads below the sharp spike necessary for impact failure. Also, even grade 8 bolts aren't all that brittle; after they're heat treated to get the ultimate strength up they're tempered to bring back the impact strength. Impact strength might be an issue if something's loose, so that it shifts and bangs around before it hits whatever is stopping it (i.e. the loose bolt).

Conclusion: Grade 8 bolts are stronger in virtually any application on a Jeep. Whether you need that strength, and want to pay extra for it, is another issue (though I bought some 5/16 grade 8's yesterday for $0.60 each; grade 5's were only ten cents cheaper). There may also be situations where you may want the bolt to fail before the expensive part it's holding breaks, but that's another issue.

FWIW, "aircraft grade" bolts (AN or MS) are generally grade 8's will additional testing and quality control requirements-- not a bad idea for the bolts holding your wing on at 10,000 feet.

Fine or coarse thread? Fine thread bolts are generally stronger in tension as they have a greater cross-sectional area (the finer threads don't cut as deep). They can also develop greater clamping forces at reasonable torque values (cylinder head bolts are a good example). However, when threaded into a softer metal (like aluminum) coarse threads have less of a tendency to strip out, and are the better choice.

-Dana

Balance the budget--declare politicians a game species.
 
G

·
Discussion Starter · #17 ·
A person in my club was being tugged out of a bog by another Jeeper when the grade 8 bolts came out of the tow hooks. They actually stripped the threads right out of the frame. The result was a projectile tow hook that went THROUGH the tail gate of the tugging TJ and and a tow strap that went through the back of the Jeep (summer, no window) hitting the driver in the head. Another few inches higher and the tow hook would have killed her. The tow hooks have been welded in place ever scince.

Aaron.

 
G

·
Discussion Starter · #18 ·
I stayed out of this this time because I distinctly remember this whole thing from last time, but I'm still a little in the dark as to why all the hardware that came with my Warn channel mount was grade 5, you would think a company that has as big a rep and has been around such a long time would have a darn good reason not to go with grade 8, the cost difference wouldn't be more than a couple bucks

Brad
ORC Land Use Section Editor
Get involved or lose it all, the choice is yours!
 

·
Registered
Joined
·
6,394 Posts
/wwwthreads_images/icons/tongue.gif Despite what I've read here on this thread, Brad, my vote is still the Gr 5, fine thread. I think it offers adequate strength and durability for that application. HOWEVER.....the few times that I wanted to really hold something that was giving trouble, we used Caterpillar track pad bolts and tightened them to 250 Ft Lbs of torque. We had a gear that kept loosening the ring of bolts holding it to the shaft flange. Those Cat bolts DID solve the problem/wwwthreads_images/icons/tongue.gif. So you can always get some track pad bolts off a nearby Cat./wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.
 

·
Registered
Joined
·
7,409 Posts
Brad I kinda have to agree with you. My 1/2" grade 5 fine thread bolts in my front tow hooks are stronger than the frame.(IMO) I had them laying around at the time. When I have to buy them it's grade8 though.

"No officer I haven't been drinking , Thats just how my Jeep drives"
 
1 - 20 of 30 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top