Tow hooks

MATT4U · Post by **MATT4U** » Wed Oct 18, 2006 4:11 pm

For all of you who dont understand how importent it is to not only have rated hooks but mount them correctly but also check the mountings and bolts.

On the weekend we went for a drive out the waimak and decided to pop past the play pit and see who was there. We came accross some people trying to recover a hilux surf that was stuck front first down a hole, they had been trying to pull him back up and out of it and disaster hit, the hook on the tow vehicle broke the bolts, went through the rear window shattering it and lodged itself in the roof of the surf above the rear seats. Apparently there were kids in the back seat whe this happened but I was ot there to see.

When we arrived we offered to help and tryed to pull him out fowards, on of his mates connected the rope to the front of his truck, when asked it it was a rated hook he connected to he said it was just as good. about 10 seconds later we had ripped his bullbars off the chassie!!!

In the end we high lifted the rear, dug out under the diff and winched with a safari PTO and a pully block with another safari as an anchour.

So just as a warning, Check your hooks and bolts :!:

Ryan · Post by **Ryan** » Wed Oct 18, 2006 5:23 pm

Fark!!!!

jst picked up a rated tow hook today!!phew...

niblik · Post by **niblik** » Wed Oct 18, 2006 6:20 pm

nice work matt.. and a great photo for education purposes...

cowboys aye.. :roll:

dixie · Post by **dixie** » Wed Oct 18, 2006 11:06 pm

FAARRRKKK isnt the word.That is nasty shit,ive just fitted 4 rated hooks to my truck and made sure the buggas dont pull out(fingers crossed).Front eyes are bolted through about 35-40 ml steel and rear about 20ml,with the intention off not having shit like that happen!!!.

Great detail Matt,more examples like this should be posted to make people aware of manmade failures.

Jerry · Post by **Jerry** » Fri Oct 20, 2006 8:47 am

The Rated hooks should usually straighten first releasing the strop/rope rather than snap or come off the mount (if mounted properly).

MATT4U · Post by **MATT4U** » Fri Oct 20, 2006 4:33 pm

I would guess the bolts were loose causing them to break

mroffroader · Post by **mroffroader** » Fri Oct 20, 2006 5:23 pm

SHIT!!!! lucky noone was injured cowboys or not

daisy · Post by **daisy** » Fri Oct 20, 2006 7:12 pm

4x4skid · Post by **4x4skid** » Wed May 02, 2007 7:14 pm

sooooooooooooooo lucky, ive heard stories of the like how ever my only bad luck recovery was a rope moving half off the hook with the river curent, it was a factory hook with a flat end, alowing the snatchy to gather reasonalble force before sliping off and becoming airborn this was only a snatchy that came off and not at full tention but was still enuf to create e reasonable hand size dent in my tail door!

mounting tow hooks and atatching ropes is never a time 4 she'll be rite, i now have a small ring of bike tube rubber on the end of my ropes just slid it up to the hook if 1 end is in water, i have 2 rated hooks on each end of my truck aswell as a locking pinical hook at the back, all mounted 2 never pull off.

have thought about changing my bolts to cap screws, (alen key heads) they are the highest tensile available, i think 12.6grade they dont even make them in lower grade or mild steel, so you cant get the rong ones, this would definatly solve any chance of bolts bending/breaking however the thread on the nuts remains the same. double nuting will slightly improve the thread strength and will help keep tite especialy if the 2nd nut is a nylock, Locktite is very good, however can make removal without a gas torch can be dificult but realy how often do you take your towhooks off?

my 3c worth anyway

cheers skid

Cloggy_NZ · Post by **Cloggy_NZ** » Wed May 02, 2007 8:04 pm

Just as important as using the right bolts is tightening them to the right torque. Over tightening is as bad if not worse than not tightening enough.
It doesn't matter how strong the bolts are, if they are very close or have gone past their point of elasticity they might as well be soft galvanised construction type bolts you buy at Bunnings or the like.
Question is, what is the right torque setting for the various grades, sizes and threads of bolts. Does anyone on here have the answer to this?
I believe the margin of error decreases as the tensile strengtht of the bolt increases.

rowinz · Post by **rowinz** » Wed May 02, 2007 8:36 pm

NZ4WD magazine did failure test article a while back. Don't know what yr/month as I only keep the articles I want and discard rest of mag. They stated 57ft lb for Gr 8.8 bolts.

Thats what I use, getting bolts from Black Fasteners. DIY stores either don't stock high tensile bolts or they charge the earth for them.

The mounting point is just as important, as recent posts highlight.

Daz · Post by **Daz** » Wed May 02, 2007 10:09 pm

Have a look at this

http://www.norbar.com/torquetensioncalculator.php

tallsam66 · Post by **tallsam66** » Wed May 02, 2007 10:30 pm

Yep..the type of hook or eye & how they are mounted is important..but dont forget there are many other just as impotant things that need to be done including

Using the right method..ie winching or snatching or even digging.

Using the correct amout of force..too much can & does break hooks..bend chassis etc.

Keeping people clear of the area should a cable ,strap or rope break.

Using a dampning device should cable etc break to absorb a lot of the energy cable.

etc..etc etc.