https://www.youtube.com/embed/qGR45KtUons
That cheap tow hook should be just fine in case you need to get rescued from an on-track incident, right?
To find out, we compared a tow hook from 034Motorsport–the one we put on our Volkswagen GTI project car–against the cheapest tow hook we could find on the internet.
Pres…
Pedant warning. Nothing wrong with aluminum. Everything wrong with cheap under engineered garbage with very sketchy metallurgy.
I have the Toyobaru version of that exact same cheapo hook, I bought it mainly so I would have a 2nd hook and could attach two at once, but I thought it could be a totally functional hook. I already had one fun incident when I first took it out of the box, played with it a bit, and put it back. I then noticed that my hands felt slick, some protective oil from the tow hook perhaps? No, it was blood, the CNC'd edges were so incredibly sharp that they cut my hands up and I didn't even feel it. I filed down the edges after that.
I think I'll put that tow hook up for sale now with a warning that it's for ornamental use only.
Is hitting it from the side with a hammer really testing the hook properly? They're designed for pulling. This test best approximates a side pull using a chain or a non-kinetic rope and a running start on the tow vehicle. Totally plausible in a redneck mud recovery, but is it likely with a racetrack recovery? How does the cheap tow hook do on a sustained hard off-angle pull if you don't leave a gap between the lock nut and the body - it could have been at least a half turn closer? What exactly is wrong with the threads on the cheapie?
Also, how did the sponsor's tow hook deal with the hammer test?
Keith Tanner said:Is hitting it from the side with a hammer really testing the hook properly? They're designed for pulling. This test best approximates a side pull using a chain or a non-kinetic rope and a running start on the tow vehicle. Totally plausible in a redneck mud recovery, but is it likely with a racetrack recovery? How does the cheap tow hook do on a sustained hard off-angle pull if you don't leave a gap between the lock nut and the body - it could have been at least a half turn closer? What exactly is wrong with the threads on the cheapie?
Also, how did the sponsor's tow hook deal with the hammer test?
My thoughts exactly. That particular test may not show how it performs under a tow, but it does show how it'll perform if you hit a wall. Of course, if that happens, you got bigger problems than worrying about how the tow driver decided to hook up your car.
Also, I wouldn't hit a $150 tow hook with a hammer either. :)
I really like the part where you acknowledge that the OEM tow hook is perfectly fine and then decide not to use it.
Before deciding that you want to use the factory tow hook lug take a look at how it's attached to the car. A surprising number of them are welded on in such a way that any side pull will bend them brining the hook in contact with the bumper cover.
Some backstory: The idea for this video came when I ordered a tow hook for the 350Z, and was appalled at how poorly what they sent me was made out of. I expected cheap, but I didn't expect dangerous. So we put this together with the three options: Cheap, OEM, and blingy aftermarket.
The hammer definitely wasn't a perfect test, but the goal wasn't to do a perfect test: It was to spotlight what the cheap tow hook was made out of in a very easy to digest way. I did draw up the plans to use the F-250's winch, a tree, a salvage Golf bumper beam, and an industrial force gauge to do some scientific tests without shock loads and without any deflection, but ultimately we decided against that for a few reasons: 1. The cheap tow hook was so bad it wouldn't have survived even a few seconds of testing. And 2. Simplifying all of it to meet YouTube's demands just didn't seem possible. So we went with the hammer, as a shock-loaded side pull is super possible at the track: Spin into gravel and you'll get one free courtesy of the track safety workers.
As far as this vs. the OEM hook: different people play at different budgets, and I think it was right to acknowledge the 034 hook is part bling, and part leaving it on the car all the time, but ultimately no better for towing than the OEM hook.
034 Hook Hammer Test:
Keith Tanner said:What exactly is wrong with the threads on the cheapie?
They're a completely different profile than the threads in the bumper beam. The 034 and OEM hooks take the load across those big flat 45-degree faces of the threads, while the cheap one puts all that force on the edge of those square shoulders.
Keith Tanner said:What exactly is wrong with the threads on the cheapie?
When I watched the video, I noted that the factory threads appeared to be BUTTRESS threads, not typical symmetric threads. More or less designed for better pullout strength. They are likely also slightly tapered to lock in the receiver more solidly.
In reply to APEowner :
That's been a thing with Miatas since day 1. The cars come with "baby teeth" tie downs that are used for shipping. If you use them for towing, you can easily get into the bumper cover and Mazda warned very strongly against trying. They're just so tempting! You're supposed to pull the teeth on delivery of the car, but it didn't happen on a very large number of them.
You could hit one of those with a hammer until your arm fell off though :)
Keith Tanner said:That's been a thing with Miatas since day 1. The cars come with "baby teeth" tie downs that are used for shipping. If you use them for towing, you can easily get into the bumper cover and Mazda warned very strongly against trying. They're just so tempting! You're supposed to pull the teeth on delivery of the car, but it didn't happen on a very large number of them.
You could hit one of those with a hammer until your arm fell off though :)
The common spec miata tow hooks use the same mounting points as the baby teeth, but with a longer piece of metal so that it clears the bumper. They're a flat piece of plate without any reinforcement so they do tend to bend a little in the thin direction when you use them to pull a car.
Thanks for the thread update, I'm not enough of an engineer to be able to decipher thread profiles.
Tom, from an entertainment value standpoint, I'm very disappointed you decided not to go through with the winch test. It would have been a lot more fun to watch.
I've only been pulled out of the gravel once, and it was a smooth winch and not a snatch. I didn't have all my wheels at the time so getting towed back to the pits wasn't really an option, though.
Tom Suddard said:Some backstory: The idea for this video came when I ordered a tow hook for the 350Z, and was appalled at how poorly what they sent me was made out of. I expected cheap, but I didn't expect dangerous. So we put this together with the three options: Cheap, OEM, and blingy aftermarket.
The hammer definitely wasn't a perfect test, but the goal wasn't to do a perfect test: It was to spotlight what the cheap tow hook was made out of in a very easy to digest way. I did draw up the plans to use the F-250's winch, a tree, a salvage Golf bumper beam, and an industrial force gauge to do some scientific tests without shock loads and without any deflection, but ultimately we decided against that for a few reasons: 1. The cheap tow hook was so bad it wouldn't have survived even a few seconds of testing. And 2. Simplifying all of it to meet YouTube's demands just didn't seem possible. So we went with the hammer, as a shock-loaded side pull is super possible at the track: Spin into gravel and you'll get one free courtesy of the track safety workers.
As far as this vs. the OEM hook: different people play at different budgets, and I think it was right to acknowledge the 034 hook is part bling, and part leaving it on the car all the time, but ultimately no better for towing than the OEM hook.
034 Hook Hammer Test:
Other than material, I see one other difference in design - the male threads are on the hook, not the extension. I suspect they're larger diameter as well. I'm not sure the design difference would have mattered, although it does mean a little less leverage on the break point.
Is there a common thread and pitch for the stock tow hook ?
Would a screw in tow hook from a heavy Mercedes be better than one from a Prius etc
I just wonder how strong the Plate that is part of the chassis is attached ,
Just wondering if we need to be buying heavy duty ones at the junkyard ?
That's just not a thing that should be made of aluminum.
californiamilleghia said:Is there a common thread and pitch for the stock tow hook ?
Would a screw in tow hook from a heavy Mercedes be better than one from a Prius etc
I just wonder how strong the Plate that is part of the chassis is attached ,
Just wondering if we need to be buying heavy duty ones at the junkyard ?
No, there's no standard. And many makes change the thread based on year/make/model. 350Zs have at least two different tow hooks, for example.
In reply to Keith Tanner :
Yeah, the whole assembly is significantly larger diameter.
In reply to californiamilleghia :
There is not a universal one. There might be some common ones, but I can tell you that the thread pitch for a Tesla and an ND Miata are different.
Maybe I'll keep mine and test it to destruction for science, it's probably only worth like $15 used. I just tested the materials with some magnets, the only parts that got any reaction were the bolts at the hinge point holding the tow ring to the piece at the end of the shaft. Nothing from the nut that locks that piece onto the shaft even.
We made ours out of 1/4 inch steel plate and used the bumper bracket location on the Datsun.
For the Formula 500 it's not an issue as the safety crews just use the roll hoop.
In reply to Streetwiseguy :
I 6061T6 version of thst would be ok. Given the right engineering.
https://royalhooks.com/products/hitch-hook-tow-hook-for-2-inch-receiver-aluminum-royal-hooks-raw
that hook is rated to 20klbs and is made of aluminum.
Sheer testing is not the same as tensile testing, additionally shock testing with an impact is not the same as a steady pull.
while testing ultimate tensile strength would require somewhat specialized equipment, it would be exciting. Especially if you get one big enough to fail the stock or good aftermarket ones. Hell, the tensile tester I used in college would make a heavy lab table jump failing a steel sample the diameter of a pencil.
Simply put the aluminium one has several issues, it would be highly susceptible to deformation and ultimately fracture on off-center loads (which is probably the most likely failure mode in service) and I do not believe that the thread root would posses much tensile strength in that material, especially if coupled with an off axis pull. I suspect that the fine threads on the outboard portion would fail at the sharp transition point due to the sharp angle stress riser.
This is a tow hook:
This is a novelty item:
ChampCar is doing away with rigid tow hooks this year. Are they the only ones that are doing this? This is from the 2023 rules: Rigid tow hooks that protrude beyond the bumper are strongly discouraged. Effective 01Jul2023 Rigid tow hooks extending beyond the bumper will not be permitted.
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