Spider Crash Test Report

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Spider Crash Test Report

Post by rridge » Tue Jan 22, 2019 6:00 pm

In 1978 the U.S. National Highway Traffic Safety Administration (NHTSA) sponsored some tests of a 1978 Spider. The main purpose was to see if the fuel tank ruptured in a rear ender. A moving trolley with a large flat vertical front end hit the rear of the Spider at 30 mph. The results were interesting. The tail of the car moved downward as it crushed aproximate 18 inches but the fuel tank remained intact and no fuel was released from the full tank.

Two test dummies were in the front seats. At impact both seats slid back to the end of their tracks and the backrests collapsed backwards at about 45 degrees, stopped only by contact with the rear seat bottom. The dummy's slid up and backwards in their seats. One dummy's head contacted the convertible rear window but did not go through it. The report notes that both doors could be opened after impact and neither dummy suffered serious injuries. Take away the rear bumper, add a roll bar behind the front seats, and put the top down and the results might have been different.

The written report and a 30 second video can be found here: https://www-nrd.nhtsa.dot.gov/database/ ... px?LJC=110
Richard
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Re: Spider Crash Test Report

Post by friedman » Wed Jan 23, 2019 8:58 am

I was not able to see the video but based on your explanation of what happened to the dummies, I agree that a street rollbar might actually kill you with severe head trauma. Was it a fault of seat design?
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Re: Spider Crash Test Report

Post by rridge » Wed Jan 23, 2019 9:21 am

I don't know whether the recliner mechanisms or the seat back frames failed. Both are known Spider weak points. Putting aside the conflict with head and roll bar, the larger problem is that when the seat back fails in a rear end collision, the body slides rearward and tends to slide out from under the lap belt, allowing it to be ejected from the car. In most cases its better to be in the car until it stops moving, particularly when the car maintains its structural integrity as the Spider apparently can.

Here's the test video on YouTube: https://www.youtube.com/watch?v=owcXQqFBu-w
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Re: Spider Crash Test Report

Post by friedman » Wed Jan 23, 2019 10:57 am

Could be your head would actually be under the roll bar as it tries to go out the rear window but then my roll bar has a diagonal in it. The odds of getting hit in the rear is way higher than your spider rolling over so if you get past the vanity aspect of having a street bar then the odds are you are safer without a roll bar. Then again, you would be safer still in an X1/9....unless it was parked in front of my house.

I think most of us realize taking a major hit in a spider is not a life enhancing experience and as I used to joke, our bodies are the crush zones in these cars. Fortunately I had 20 or so years of motorcycling to make me think any car, including a spider is safer.
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Re: Spider Crash Test Report

Post by rridge » Wed Jan 23, 2019 11:42 am

By the time most of us are thirty, we have multiple friends and classmates who have been in serious car crashes. Years ago many of those accidents were fatal or near fatal. And their outcomes tended to have more impact on us than any number of safe driving reports or crash videos.

I lost a friend in a TR3 rollover while in college. He wasn't killed by the rollover itself but by being thrown from the car into a barrier on a cloverleaf. The person who remained in the car survived.

Another friend rolled an Alfa Giulietta end over end after dropping a front wheel into a deep pothole on a country road at speed at night. The convertible top and windshield provided no protection. Both ends were flattened and the car was crushed down to the top of the dash. He survived by leaning over into the passenger seat and holding on to something to keep his torso down.

In the days before seat belts and roll bars became common this was the approved sports car driver's rollover maneuver as documented by Ken Purdy, and for rally cars running at moderate speed on road courses it worked at least occasionally. The irony is that the Alfa had replaced a Karman Ghia that both of us had always assumed to have a much higher rollover potential. Since I was always the navigator in the Ghia I made it clear to him that I had dibs on the passenger's footwell if we went shiny side down.
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Re: Spider Crash Test Report

Post by bark » Wed Jan 23, 2019 1:48 pm

Well, here's my 1970 Spider after a being rear ended by that pickup pulling a trailer full of wire. He was doing 65 MPH in the dense fog with no brakes and hit me from behind at a stop light, pushing me under a 225 and into several small Japanese cars. The roll bar saved my life, for it snagged the front bumper and prevented the truck from simply overrunning my Spider and decapitating me. You can see how far over the front seat it was pushed. I hit the bar with the back of my head, resulting in 18 stitches. I broke the steering wheel with my face, shattering my left orbit. The gas tank was just filled and did rupture. And yes, both doors still opened and closed!
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Re: Spider Crash Test Report

Post by rridge » Wed Jan 23, 2019 2:37 pm

Bill,

I'll bet that picture will get at least a few Spider owners to take a look at the new taillight circuit boards that Csaba recently mentioned.
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Re: Spider Crash Test Report

Post by scrapironchef » Wed Jan 23, 2019 3:03 pm

rridge wrote:
Wed Jan 23, 2019 2:37 pm
Bill,

I'll bet that picture will get at least a few Spider owners to take a look at the new taillight circuit boards that Csaba recently mentioned.
Upgrading to better seats is a sensible safety precaution, my RX7 seat actually rest against the roll bar. I sit a little higher than stock but the seat belt provides a little more protection that way.

I'm also mounting a brake light up on the roll bar.
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Re: Spider Crash Test Report

Post by rridge » Thu Jan 24, 2019 10:13 am

I've been hit from behind at low speed by a commercial van. The double tube 5mph rear bumper and shock mounts absorbed the blow and limited damage to some crazing in one of the tail light lenses. Fortunately my car was at stock ride height at the time. The seat back held and the head rest limited the damage to my neck as my head snapped back.

The crash occurred as a red light was turning green and it was clear that the other driver simply looked over me due to the difference in the height of our vehicles. I had my top down at the time. It doesn't help that my car is dark blue.

In the 30mph test crash the total crush distance was 18 inches. The rear bumper and struts were the first five inches of that total. Take those five inches away and you would likely have separation of the fuel filler hose from the side of the fuel tank even in a comparatively low speed accident. If the tank is more than half full, hose separation means a fuel spill.
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Re: Spider Crash Test Report

Post by fp55scca » Thu Jan 24, 2019 10:13 pm

--Wow Bill, that's a dandy!

--At the same time, there is some advantage to a car crushing like this. It does absorb energy. These cars were not designed with crumple zones, but every little bit helps.

--When my son took this '74 Spider to college circa 2009, I added a competition roll bar (with diagonal, and modified so the rag top would still fit). Also added one piece Sparco seats, and 3" lap belts. I figured it was a trade-off. "The greater the number of kids in a car, the higher the probability of an accident"? The Spider is small and vulnerable, but only carries one passenger....well normally, anyway.
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