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Welding on tow hooks?

9

98xjjeeper

NAXJA Forum User
Location
nc
Will it be strong enough if i mig weld on tow hooks or should i bolt it? Also, where should i put them, two in the front ( one on both sides), one it the middle, or what? Thanks in advance!
 
Welded tow hooks aren't allowed on runs........bolt them.

A cracked weld can turn a tow hook into a deadly projectile, so welding is not advised.
 
correct, though I've seen them work, they are dangerous and I would never hook a strap to one, or knowingly be within 100 yards of one being used.

the OEM brackets are real good, see if you can find some at a junkyard. there are many other manufacturers that make them, but be sure they tie in the hole about 6 inches behind the 3 bumper bolts.
 
mine are bolted on with 2 - 1/2" grade 8 bolts, then welded around the out side, and the nuts and bolts are also welded on
 
98xjjeeper said:
Will it be strong enough if i mig weld on tow hooks or should i bolt it? Also, where should i put them, two in the front ( one on both sides), one it the middle, or what? Thanks in advance!
Click to expand...


If youre going to do something like that, at least stick it! :D :wave:

JK, just bolt em up.
 
my understanding is that the heat generated by the welding process weakens the steel of the forged hooks. which, in turn, compromises the weight rating of the hook. i'm not a metalurgist but this was told to me by long-time welder/fabricator so i give it alot of credit.
 
sidriptide said:
my understanding is that the heat generated by the welding process weakens the steel of the forged hooks. which, in turn, compromises the weight rating of the hook. i'm not a metalurgist but this was told to me by long-time welder/fabricator so i give it alot of credit.
Click to expand...

Yeeup, I heard that too.
 
98xjjeeper said:
Will it be strong enough if i mig weld on tow hooks or should i bolt it? Also, where should i put them, two in the front ( one on both sides), one it the middle, or what? Thanks in advance!
Click to expand...

No, bolt them on. That is the most dependable way to do it. Use grade 5 hardware. Grade 5 hardware will put up with more force in shear than grade 8 because it's less brittle.

I prefer one hook (or clevis) on each side as it gives more options than just one recovery point.

,Ron
 
Zuki-Ron said:
Grade 5 hardware will put up with more force in shear than grade 8 because it's less brittle.
Click to expand...

:huh: How do you figure? My Mechanical Engineering Design text has a table listing the SAE minimum specifications for bolts. It says Grade 5 bolts up to 1" diameter have a minimum proof strength of 85 ksi, and Grade 8 bolts have a minimum proof strength of 120 ksi. Now, since the shear of a bolt is (0.577*Sp/nd), how could a Grade 5 possibly be stronger?

Putting the shear load on the unthreaded shank of the bolt would allow for a force of (0.577*pi*(d^2)*Sp/nd), right? Using two similar bolts, you'd have identical d values, and I would want the same factor of safety nd, and pi is a constant, and 0.577 is a constant. How could you possibly have a higher allowable force, with a lower proof strength Sp?

If I missed something, please help me, because I've got a final exam coming up.
 
Phil said:
:huh: How do you figure? My Mechanical Engineering Design text has a table listing the SAE minimum specifications for bolts. It says Grade 5 bolts up to 1" diameter have a minimum proof strength of 85 ksi, and Grade 8 bolts have a minimum proof strength of 120 ksi. Now, since the shear of a bolt is (0.577*Sp/nd), how could a Grade 5 possibly be stronger?

Putting the shear load on the unthreaded shank of the bolt would allow for a force of (0.577*pi*(d^2)*Sp/nd), right? Using two similar bolts, you'd have identical d values, and I would want the same factor of safety nd, and pi is a constant, and 0.577 is a constant. How could you possibly have a higher allowable force, with a lower proof strength Sp?

If I missed something, please help me, because I've got a final exam coming up.
Click to expand...

Thank you Phil for clearing that up.

You are very correct, BTW.
 
the common misconseption is that grade 5 will give a little more and bend before it breaks giving you a warnign sign. well grade 5 may bend but grade eight's yeild strength is stronger than grade 5's break strength.
 
I would deff. bolt them on it can and will weaken them metal on the hook. I am a certified structural steel welder that builds bucket trucks for electric companies and phone companies and have dealt with this question directly with customers. seeing as alot of the trucks i build get heavy duty tow hooks bolted to the front end they always ask why can't we weld them.

and if it matters we ALWAYS use grade 8 when we bolt them down
 
Me too, bolt them. I was taught that the heat of the weld decarbonizes the metal, that's where the strength is. Maybe that's why some racing events don't use chromed parts for the same reason. I can weld, but I'm not a professional welder however. Maybe that's what sidriptide was talking about the temper.
 
I'm surprised nobody has asked the number one question reguarding tow hooks...

98xjjeeper just where do you plan to bolt these tow hooks?

You cannot just bolt the hooks straight to the bumper, body, or "frame" or you will suffer very, very bad things.
 
Thanks for the help guys.

GSequoia said:
I'm surprised nobody has asked the number one question reguarding tow hooks...

98xjjeeper just where do you plan to bolt these tow hooks?

You cannot just bolt the hooks straight to the bumper, body, or "frame" or you will suffer very, very bad things.
Click to expand...

I am new to this so sorry if i sound dumb. I thought you can just drill some holes and bolt them up on the frame.
 
98xjjeeper said:
I am new to this so sorry if i sound dumb. I thought you can just drill some holes and bolt them up on the frame.
Click to expand...

Just so you know...

XJ's don't have a "frame" per se...

Unibody/uniframe...

There's a few companies that sell a kit that includes a nice beefy bracket suitable and strong enough for mounting tow hooks...
 
Gil BullyKatz said:
Just so you know...

XJ's don't have a "frame" per se...

Unibody/uniframe...

There's a few companies that sell a kit that includes a nice beefy bracket suitable and strong enough for mounting tow hooks...
Click to expand...

BINGO! Gil gets a cookie.

You can't bolt 'em on, you need Tow Hook Brackets otherwise you risk serious injury. Get the good ones that look like the picture below. If they do not extend back at the "frame" they may pull off.

If you have a late model XJ I would recommend aftermarket brackets that extend back like the picture or it may tear off (I've seen it happen).

Good tow hook brackets:
towhookbrackets.gif
 
bj-666 said:
the common misconseption is that grade 5 will give a little more and bend before it breaks giving you a warnign sign. well grade 5 may bend but grade eight's yeild strength is stronger than grade 5's break strength.
Click to expand...

That appears to be the missconception that I was under as it was my understanding that a grade 8 would fail in shear before a grade 5 because it is more brittle. After examining the formulas involved, I am required to retract this statement:
Grade 5 hardware will put up with more force in shear than grade 8 because it's less brittle.
Click to expand...
,Ron
 
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