Auto Sheetmetal thickness

My 50 F1 pu is 19 gage not sure about other vehicles though. Ed ke6bnl

That is interesting. I would bet that a new Ford pickup is using 22 to 24 gauge steel.

Jim

New cars use medium- and high- strength low alloy steels that are much stronger than the mild steel used in older cars. There are also differences in frame construction--i.e. the unibody.

See:

I don't have data on thicknesses, but the trend has been thinner in recent years.

Jeff Dantzler

In addition to thicker sheet metal, its been claimed that most early 50's era cars would crash test better than new cars, at least as far as the driver's compartment goes, because there is more metal enclosing the drivers compartment in the older cars compared to the "greenhouse of glass" on the newer cars.

It also seems that you often hear that cars are breaking in two halfs in a bad crash with today's cars. I don't remember that happening very often back in the old days. So have all these safety laws really done much for us, other than seat belts and air bags?

Paul T.

So where has the huge improvement in driver survivabilty come from ? I don't want my car to be in fine shape, while I am smashed to pieces inside a 1950s car....Modern vehicles have very carefully designed crush and crumplezones which exclude the passenger compartments.

Steve

My parents' 1987 Nissan Stanza wagon was broadsided by a Ford F-350 farm truck about 15 years ago. The drivers side door was driven 2 feet into the car. My brother was driving and suffered a punctured lung. My dad was in the pasenger seat and suffered bruising. My Mom was in the back and slammed from the passenger side to the drivers. side permanently damaging her shoulder.

I wennt to the wrecking yard to see what we could pull out of their personal effects.

The car looked like a stepped on coke can, and yet all the doors not directly impacted opened just fine. The owner of the wrecking yard said that he had been wrecking cars for

40 years and 40 years ago he would get in a Packard with a dent in the fender where nobody survived inside the car. Now, he said, I pull in crushed pop cans where everybody gets out alive. Progress?, well maybe if you want to live in an accident, but it sure cuts into the profits from selling used car parts.

Seat belts primarily prevent occupant ejection in a crash, and that's usually a good thing, but they do little to reduce the forces on the occupant's body in a crash. Air bags buffer the impact between the occupant and the interior of the car in a frontal crash, also usually a good thing, except when their deployment in a multiple impact crash, or a false trigger deployment, causes the driver to lose control.

But the big improvements in survivability in crashes is due to the

*controlled* crush and crumple zones designed into modern cars. This dramatically reduces the G forces endured by the occupants. In other words, the sudden stop isn't quite so sudden when the car is able to crumple. As has been said many times with regard to falls, it isn't the fall that kills you, it is the sudden stop at the end.

Same thing in a collision, the longer you can prolong deceleration, the lower the peak force the occupant's body has to endure. The time involved to make a dramatic difference isn't all that much either. For example, if a crumple zone can prolong deceleration from 1 millisecond to 10 milliseconds, the force on the occupant decreases

10 times, if 100 milliseconds 100 times, etc.

Most modern cars have crumple zones that reduce impact forces on the occupant by 5 to 10 times compared to cars from the 1950s. The best ones reduce the forces by nearly 100 times.

Also, most modern FWD cars are designed so that the engine and transmission break away and submarine below the passenger compartment in a frontal collision. This prevents the motor from intruding into the passenger compartment, as was often the case with older designs. Some front engine RWD cars are designed to do the same (they use carbon fiber drive shafts designed to shatter in an impact and allow the engine and transmission to move down and to the rear without becoming a pogo stick). Of course steering columns are collapsible, so they don't spear the driver in a crash. Etc.

The passenger compartments themselves have been reinforced so that they don't collapse in on the occupant in a crash or rollover. There are side door beams, stronger A pillars, etc. They certainly aren't as good as a NASCAR cage, but they are remarkably more effective than just the heavier sheetmetal in older cars. The interiors of cars have had hard and sharp things removed too, so if the occupant does strike a part of the interior, less damage will be inflicted.

The fatality rate per 100,000 miles driven dropped *dramatically* between 1950 and 2000, with most of the drop occurring in the last decade. That's primarily due to the use of CAD to purpose design in optimized crush zones, and to strengthen the passenger compartment *in the right places* to minimize intrusions into that space in a crash.

It is worth noting that my Nissan 350Z, one of the best rated cars for crash survivability, actually weighs more than a 57 Chevy. So does the 2005 Corvette. Think about that, today's small 2 seater sports cars weigh more than a full size 50s sedan. Much more of that weight is in the *right places* to reduce impact forces on a driver in a collision, and to prevent intrusions into the passenger compartment.

This weight thing surprised me a bit. The 350Z weighs 3450 pounds, the new Corvette weighs 3224 pounds, a 57 Chevy Belaire (283 with Powerglide) weighed 3175 pounds. Now considering that the modern cars make extensive use of aluminum, plastics, and thinner sheetmetal, that extra weight has been put into the structure *where it counts* for crash survivability. Cars are no longer just sheetmetal boxes sitting on a pair of C channel rails.

Gary

I don't know what gauge is used, but I believe it varies with the manufacturer. I recently took our PT Cruiser to Dent Masters for an estimate ($1,700) and he said if it was a Honda the damage would have been much worse. The sheetmetal of new cars is very flexible, just press with your thumb (carefully!). Like others have said, the new designs are made to same the occupants, not the car itself. My Challenger has real steel, hee hee.

The bumpers on 55 and 57 Fords were made from tough and thick steel.

I remember being rear ended in my T-Bird and had all 4 quarters bent, both bumpers. The 55 Ford in front of us didn't get a scratch on the bumper. The heavy frame and strong bumper just crumpled the front end. The Bird never flew with me again. The drunk went to jail.

Martin