IL Gauging interest in 1972 extreme bend tow hooks

[Nitis]

I'm trying to wrap my head around what the liability would even be? That you might break one?

I'm sure a simple disclaimer stating the facts or not intended for use just for looks type thing would suffice.

Hey if you're scared go to church!

[Jeff's bowtie's]

Heck mold them out of black plastic they'd be for looks anyway if you do hook to something it's to pull forward like a broke down ford

[ho70]

THANKS
to you and all that reproduce parts for us. It is a lot of time, effort and work and I and many here appreciate your efforts.

[raggedjim]

If fasteners are 5/8" (thanks Jeff) grade 8 then they have a cross-sectional stress area of ~.226 sq in. This gives a tensile strength of ~34,000 and since they would be used in a shear you have to multiply by .6 (actually a bit more, but we should err on the side of caution) for ~21000 lbs times two fasteners for each hook (this is just a swag guys) giving a shear strength of about 41,000 lbs.

I believe in most cases it is safer if the hook bends before a shear situation occurs...

JMHO, Rg

[Jeff's bowtie's]

The bolt size are 5/8" grade 8

[72CSCC]

There are many other factors that go into the stress calculation, such as the moment that will have to countered due to the offset of the pull point relative to the hole pattern. Guesstimating the dimensions, the holes look to be about 2.5 in apart. Conservatively assume 2". Assume 4" pull from center of bolt pattern. 5/8 GR 8 Bolt, .306 in2, 90000psi shear ult., = 27600 lbs. ultimate capacity.

This gives about 8000 lbs pull at the hook to shear the nearest bolt, provided the pull is normal to the plane created by the two fasteners.

This will be the failure mode.

[68350]

Personally I think the original poster deserves a lot of thanks for doing the leg work to get this done. If someone buys a set, its their own risk. I have a blazer with factory tow hooks and the previous owner got stuck. They pulled on the tow hook so hard it actually ripped through the frame, tow hook and bolt were not bent.

[72CSCC]

Oops - recalc. Wrong center distance.

4" from center: 11000 lbs max hook capacity.
5" from center: 9200 lbs max hook capacity.

A forged hook will still be stronger.

[raggedjim]

Originally Posted by 72CSCC

Oops - recalc. Wrong center distance.

4" from center: 11000 lbs max hook capacity.
5" from center: 9200 lbs max hook capacity.

A forged hook will still be stronger.

Nice work, Rg

[undertaker72]

Originally Posted by 68350

Personally I think the original poster deserves a lot of thanks for doing the leg work to get this done. If someone buys a set, its their own risk. I have a blazer with factory tow hooks and the previous owner got stuck. They pulled on the tow hook so hard it actually ripped through the frame, tow hook and bolt were not bent.

I agree we did a side type angle pull , on both hooks with a center bridle , and believe me you , it bent the front frame horns , it was mired in mud to the coffee cups of the fenders and we only had one winch approach , the hooks held well

[teds72]

please send pic's when you get them Thanks Ted

[Kennuck]

Originally Posted by The Rocknrod

Since you will be buying these and using them at your own risk, the liability will be with you the buyer. Do you ask what liability AMD has on their products? and their a large company. Some guy is trying to help the community out and you (some internet lawyer) try and stop him in his tracks. Thanks.
Use em at your own risk. If you buy them and beat your wife with them over the head is he liable?

I'm not a Lawyer by any means, and your attacking me doesn't change a thing. In fact there are a lot of others contributing constructively to the conversation. Just because you want these so bad that you couldn't care less about the op is no reason to get upset. You would probably be the first one to sue if they failed and injured you or someone else.

I never said he shouldn't do it I was merely suggesting he do his homework. It is a litigious society we live in these days.

Oh I'm not a wife beater either!

[72CSCC]

Tough question. If GM was going for it, they may have specified 4130 or 4340 steel for the forging. That would be pretty cool - but overkill. As someone mentioned before, the frame horns will be the weak point in this system, and that is not the failure point you want. They are likely a fairly common carbon steel.

Here at work, we have a tool that looks like a timing light that you can point at metal, and it will read out the chemical composition. (EXPENSIVE tool). Once I have some hooks I will do this, and the properties will be determined easily.

[undertaker72]

Originally Posted by 72CSCC

Tough question. If GM was going for it, they may have specified 4130 or 4340 steel for the forging. That would be pretty cool - but overkill. As someone mentioned before, the frame horns will be the weak point in this system, and that is not the failure point you want. They are likely a fairly common carbon steel.

Here at work, we have a tool that looks like a timing light that you can point at metal, and it will read out the chemical composition. (EXPENSIVE tool). Once I have some hooks I will do this, and the properties will be determined easily.

must be a kevex , ive played a few times with those

[72 tigger]

I would be interested in a set- thanks for offering them

[c3vette4spd]

UPDATE:
I sent both of my hooks to the foundry that's going to do this for me. We had a conference call this morning. I expressed ALL the concerns of the forum members. As a result, he's going to take a sample of one of mine which sucks a nut because they were so expensive... But in doing so, he can have them analyzed and can copy these hooks verbatim. That's the truth and the fact of the matter. These will be EXACT replicas in every way with the exception of the casting numbers of course.

I'm going ahead with this project, there will be 25 sets made. I'm keeping a set for myself and I'm giving a set to my boy. 23 sets will be available for sale. I'll let you all know when I receive them.

[gmc 2500 4x4]

[Nitis]

Spending on how this goes is this a one and done or is it possible there will be future runs?

[The Rocknrod]

Originally Posted by 72CSCC

...Here at work, we have a tool that looks like a timing light that you can point at metal, and it will read out the chemical composition. (EXPENSIVE tool). Once I have some hooks I will do this, and the properties will be determined easily.

I work in the turbine industry and we use one of those. The problem arises when the exact metal composition is not loaded into the unit. Then it gives you the closest it can but not exact.

[Sikorsky72]

I hope this is still a thing because I am interested.

[dirish]

I'll jump in line, thanks.

[67-72trucks]

I would be interested in a set.

[67swb72klb]

Put me in too

[3sonsdad]

I would be in for a set.

[Ugly 61]

I'm in for a set. Let me know when they are available
Ugly 61