Safety Issues with Seat Belt Article in Current MAN.

[Kevin in NJ]

I just received my Model A News. I came to the article on installing seat belts and feel I must bring up some safety issues.

The physics of a seat belt in an accident is that all the attachment points are pulled along their strongest direction. Bolts are put into shear with wide thick washers to distribute force. You will notice the belts are usually mounted back behind the seat in a long straight line.
So when you design a seat belt mount you have to take all this into consideration. You want as straight a line from the anchor point to where it comes up around your hips.

Take a look at the diagram that was shown in the article. You will see the mount is a couple of soft all thread bolts attached to a thin piece of flat metal. The path of the seat belt winds around the seat cushions. The all thread metal piece is extended well above the mount on the sill rails with almost no extra re-enforcement. Too much room for movement of the soft metal.

In the unfortunate event of a quick stop...
The belt material will pull tight against the cushions allowing the person to slide forward. Then the flat steel and soft all thread will bend. This will further give more length to the belt. The countersunk screws are really bad. Very little contact area so they have no strength. It does not take much to pull them out of soft thin steel.
I have attached a scan of the drawing provided in the article. I have added the path of the belt when tension is pulled on the belt.

While the system is better then nothing, I feel it is not likely to hold against much force. I am really concerned that the countersunk screws might pull out easier then you might expect. I am sure an experienced mechancial engineer would be quick to see these issues.

A better way, but more work, would be to cut a hole in the curved metal piece and run the belt in a more straight path rear ward. Then make a brace on the floor area of the rumble to attach the seat belt mount bracket.

For my cabriolet I had some wood to deal with so the idea is a bit different. I made a piece of 1/2" steel bar that screws to the bottom of the wood cross sill with a bunch of wood screws and under the rear metal cross sill. The forces in an accident will be at an angle with most translated to a forward movement against the heavy wood with some of the force pulling up.
I cut a hole in that curved metal part to allow the seat belt to take the straightest path. The mount point for the belt was put back some in the area where feet go for the rumble passengers.
The side mounts are also put rear ward to make for straight lines. They go into the wood with large thick washers.

Keep in mind seat belt installations in the A are always a compromise. Some kind of seat belt is better then none. I feel what was written in the MAN may not be very good and with the countersunk screw maybe even dangerous.

I hope I have not offended anyone.

Now onto an idea for the rumble seat. The rumble seat is very difficult to make a proper seat belt mount point. There is just no room. So I made a lot of compromises. I have included a picture of what I have done. Heavy 1" square tubing under the sills. Then some tabs slipped up through the rumble riser. It is very tight with little room up the back of the seat bottom. Here is a case where way less then optimum mounting happens. The torque on the bar is not good and the tab might bend. Not much you can do.

[glenn in camino]

I have seat belts in all my Model As, mostly to keep from falling out when the doors pop open in a crash. However, I don't expect them to save me in a really bad crash.

[BRENT in 10-uh-C]

Originally Posted by glenn in camino

I have seat belts in all my Model As, mostly to keep from falling out when the doors pop open in a crash. However, I don't expect them to save me in a really bad crash.

But therein lies the problem. Suppose someone rides with you somewhere in your A, and you are involved in a fatal crash. I have been advised by legal counsel that an argument could be made by the estate where there was reasonable expectation the safety belt should have held the rider in a safe position within the car. At this point you had better have proof than an Engineer designed the installation of the seat belts and that their instructions were followed exactly. I have casually spoken with a couple Engineers regarding the seat belt installation and they all start by telling me how I need to build a quasi-cage inside the body. At that point, the aesthetics are pretty much ruined. That is why I just do/can not install them on customer's vehicles.

[MrBruce]

We are going to start making some major trips in the next few years and I am putting them in just to keep my wife and I with the car. We had a couple in our club who were hit and the wife was thrown out of the car and the driver ended up in the passenger set. Fortunately they both survived. If our 31 S/W Town Sedan gets hit, the doors will fly open. I figure if we can stay with the car we have a chance in a small accident. I know a lot of people are against putting them in. But todays traffic is not like it was in the 30's

[holdover]

I saw the article also and agree this is not how I would install them. The ones in my 3 As are installed as you mention, straight line and 1/4" metal attachment point. "Your mileage might/will vary."

[Mitch//pa]

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A little different branch here, but I recently had a customer come in who asked me to disconnect the airbag due to a medical problem with their jaw.

[Fred K-OR]

Originally Posted by Mitch//pa

A little different branch here, but I recently had a customer come in who asked me to disconnect the airbag due to a medical problem with their jaw.

Mitch, was that his wife or some other passenger?

[Mitch//pa]

Originally Posted by Fred K-OR

Mitch, was that his wife or some other passenger?

Fred
It's a woman's car and she is mainly the driver, but other family members drive it also

[emf]

This is an interesting topic. I have, for years, refused to put seat belts in any of my antique cars for one simple reason. In NY, the motor vehicle code directs that all seat belt installations must be approved by the DMV Commissioner. It's not that I think his engineering knowledge is better than mine, it a question of law. All some smart (or not so smart) lawyer needs to do is determine if your seat belts are designed appropriately. Can any of us prove that we have the training to design safety restraint systems? Here is an excerpt of NY law:

1.  Safety belts required.  No motor vehicle shall be sold or registered in this state and no motor vehicle registered in this state shall be operated in this state unless such vehicle is equipped with safety belts approved by and conforming to standards established by the commissioner.

2.  Anchorage assemblies.  No motor vehicle shall be sold or registered in this state unless such motor vehicle is equipped with safety belt assembly anchorages conforming to standards established by the commissioner for each safety belt required in such motor vehicle.


Of course, cars built before 1964 are not required to have seat belts, but if they do, the belts must conform...


Frank

[Mike V. Florida]

I find it sad that it is legally better to have no safety restraints then to have then.

[Chris in CT]

Hi Guys, What Frank has pointed out is that we have a real "Catch 22" issue here with a damned if you do and damned if you don't possible dual outcome. I think that most of us agree that we are better off having seat belts in the car than not having them. What I think we need to keep in mind is that above a certain maximum collision speed that lap-type seat belts are not going to help us. In any type of reasonably well-installed lap restraint system, the rider will be slammed against steering wheel, dash or windshield - top of body first - long before any bolts are broken or rails are torn out. I think that the best we can hope for is to be protected in a low-velocity crash, or being thrown from the car in an oblique impact situation...
With all due respect to the issue that Frank has raised, there are numerous possible responses to the regulations that he has cited, which I won't go into here. But let me point out that a reasonable and well-intentioned effort to protect passengers an a motor vehicle not required to have seat restraints due to its age could probably be argued to good effect if such a situation were ever to result in a court case.

[Kevin in NJ]

I have not gone here, but I will now.

MARC and the author has opened themselves up to a HUGE liability.

The editors should never have printed the article. If anyone does that seat belt installation and someone is injured or killed then the club and the author will be at fault. You can kiss the club goodbye.
I have a feeling that if the insurance company were to see the article you might see the club dropped like a rock.

What makes the article worse is the fact its author is a mechanical engineer with 50 years of experience. When I read that I was expecting some comments that he ran the phsyics and the numbers and developed his system based on sound engineering.
It is clear this was just thrown together with sub-standard parts. This based on common mechancial sense.

Quite frankly I believe the club is royally screwed at this point. They had best consult with their lawyers and come up with a plan of action to mitigate the damages.

I realize the magazines are hurting for quality writing, but they really need to have more considerations of material before they print.

[SeaSlugs]

Originally Posted by Kevin in NJ

I have not gone here, but I will now.

MARC and the author has opened themselves up to a HUGE liability.

The editors should never have printed the article. If anyone does that seat belt installation and someone is injured or killed then the club and the author will be at fault. You can kiss the club goodbye.
I have a feeling that if the insurance company were to see the article you might see the club dropped like a rock.

What makes the article worse is the fact its author is a mechanical engineer with 50 years of experience. When I read that I was expecting some comments that he ran the phsyics and the numbers and developed his system based on sound engineering.
It is clear this was just thrown together with sub-standard parts. This based on common mechancial sense.

Quite frankly I believe the club is royally screwed at this point. They had best consult with their lawyers and come up with a plan of action to mitigate the damages.

I realize the magazines are hurting for quality writing, but they really need to have more considerations of material before they print.

yea thats todays world unfortunately, there is always an ambulance chaser lawyer out there that would love to get his hands on articles like this so he gets tops dollar no matter the outcome or who is screwed over.

theres is ALOT of engineering involved in seatbelts, ive been in countless junkyards with modern cars and i have yet to see one cars seatbelts break or mounting holes ripped out or even bent. theres a few cars in some that its a good 95% chance people didnt survive but the seatbelts were still there. if they are broke they were either cut on purpose or jaws of life had to be used.

[denis4x4]

I cannot comprehend how the author thinks that all thread and a sheet metal floor will even begin to offer a secure mounting point for seat belts. I use a piece of channel iron as an additional cross member and 3/8" fine thread bolts with locking nuts to secure my belt anchors. Like others here, I feel that seat belts are not going to save me in a major crash.

[Kevin in NJ]

Originally Posted by denis4x4

I cannot comprehend how the author thinks that all thread and a sheet metal floor will even begin to offer a secure mounting point for seat belts. I use a piece of channel iron as an additional cross member and 3/8" fine thread bolts with locking nuts to secure my belt anchors. Like others here, I feel that seat belts are not going to save me in a major crash.

Brent brings out an interesting concept.

It does not matter what you feel the seat belts are going to do. If someone gets into your car and there are seat belts then there is a 'reasonable expectation' that they will perform to a certain level.

So you put in a seat belt and there is an accident. If the seat belt does not perform up with whatever modern expectation then you do not have a legal hope in hell. On the other hand, if there are no seat belts then all is fine.
This is really F'd up but that is how our legal system has been 'bent'.

So in essence there may be some legal reality where you have to insist that passengers do not wear seat belts that you install. Because if the seat belt fails then you are on less legal grounds then if there were no seat belts at all as the car came from the factory.

I would also suggest that you do not sell a car with the seat belts installed.

A real sad state of affairs.

[Kevin in NJ]

Oh, you may also want to print up some waivers for the dash board.

These seat belts will not function up to modern standards.
You are best not wearing them as the car came from the factory without them.

[MikeK]

I have belts in my A's and, of course, the installations have not been physically tested or independently certified. They may or may not help or save me or anyone else. My thought is this: Better to be tried by twelve than carried by six.

[Midnightcaper]

If he car didn't come with belts then it stays belt less. Personally when u turn 18 I think it should be your choice just like helmets, your a adult its your life decisions.

[Synchro909]

Originally Posted by Midnightcaper

If he car didn't come with belts then it stays belt less. Personally when u turn 18 I think it should be your choice just like helmets, your a adult its your life decisions.

When seat belts were made compulsory here in about the late 60's, some used that "It's my right to choose" argument, to which I replied, "Then it must be my right to refuse to pay my taxes that would pay for your hospital treatment."
I never had anybody come up with a worthwhile response.

[Midnightcaper]

Originally Posted by Synchro909

When seat belts were made compulsory here in about the late 60's, some used that "It's my right to choose" argument, to which I replied, "Then it must be my right to refuse to pay my taxes that would pay for your hospital treatment."
I never had anybody come up with a worthwhile response.

You can refuse to pay your taxes... Like i said your life decisions.