Car bumpers

Mar 02, 2007 58 Replies

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Bumpers on most midsize cars do a poor job of protecting the vehicles from damage in low-speed collisions, and the cost of repairs following minor fender-benders can be surprisingly steep.



Formerly one-piece steel bumpers are now integrated into the vehicle's front-end design. This happened in part because new rules don't require bumpers to be as strong and protective. That means consumers wind up paying thousands of dollars to fix damage from even a minor collision.



Even the best performers in the tests wound up badly bruised. A 5 mph impact on the front bumper of the top-ranked Mitsubishi Galant resulted in $929 of damage. A similar crash inflicted $3,911 of damage on a Subaru Legacy, $4,535 on a Nissan Maxima and $4,594 on a Volkswagen Passat.



In the tests, each car collides with a steel barrier that is shaped like the front end of a car and is built with a wide plastic cushion and a flexible cover similar to the energy-absorbing bumpers and bumper covers on most cars. The institute recently redesigned its crash barriers to look and respond more like the bumper of another vehicle instead of a flat wall. The full test includes four impacts: front and rear full-width crashes at 6 mph and front and rear corner bumps at 3 mph.



The Nissan Maxima, Pontiac G6 and Volkswagen Passat each sustained damage estimated at more than $4,500 in the frontal test. These cars have bumpers that slid underneath the barrier, allowing their bodies to absorb much of the impact. The costs reflect damage to the cars' hoods, fenders, headlights and even air conditioning condensers mounted just behind their front grilles.



Rear-end tests showed similar patterns of expensive damage when the cars' bumpers weren't tall enough or were mounted too high or low to properly engage the barrier. The Hyundai Sonata performed best in this test with $739 of damage, mostly limited to the bumper. Cars' front bumpers generally were not wide enough to prevent extensive damage in corner impacts. The headlights of all 17 cars were damaged in the 3 mph corner impacts. This is because the bumper bars aren't wide enough to protect those parts.



Many cars appear to have bumpers that wrap around their front corners, but the underlying bumper structure is rarely as extensive as the cover. On many cars there is empty space behind the corners of the bumper cover, so headlights and fenders tend to wind up absorbing the energy of the crash.



Consumers also may not be aware of the differences in the cost of repair parts from one vehicle to the next. The Toyota Camry needed extensive repairs after the rear crash test damaged its body panels and trunk floor. The cost of the repairs was $1,480, which is low compared with some other models that cost more than $3,000 to repair because their parts are more expensive than Toyota's.



I reminisce about the old style bumpers, which had nice rubber bumpers to absorb fender benders. Nowadays it's all about style and looks, not about practicality.

In 1989 I was looking for a new car and had pretty much decided on a Volvo. During a visit to the dealer/garage/repairer I was shown a 740 (one of the big blocky jobs with many attributes of a stationwagon) waiting for repair: it had rammed the side of a lorry at around 30mph with its "railway track" bumper -- a slab of aluminium, I was told -- and suffered crumpling as intended, about as far back as the front wheels, nothing worse. FWIW the driver came out intact. The garage expected to fix it up fine.

That decided me -- as it was meant to, I suspect. But a modern car... Hmm. Think I'll avoid crashes for now.

Another reason I keep my '92 Corolla Wagon....

Real bumpers.

Because there are variances in front and rear bumper height among vehicles, IMO, using a simulated bumper using an arbitrary height provides less useful information than using a wall, unless the height of the simulated bumper is adjusted to match the vehicle that is being tested.

Also, I believe that the U.S. standard for bumpers is 2.5 MPH, so a 3 MPH test is greater than the law requires. One of the main reasons for moving away from the massive steel bumpers is weight. Automakers look to the entire vehicle to improve fuel economy, and reducing bumper weight by more than half can make a measurable difference in fuel economy.

Don't fall for that BS, look at WHO is doing the testing. The insurance institutes sole purpose in testing is to establish insurance RATES. Their test are different than the NHTSA requirements.

The Insurance guys tests, just as are their offset tests, are performed at a higher speeds, are not repeatable and therefore meaningless Their test are to a different standard, at higher speeds specifically designed to CAUSE damage.

The original standard for bumpers were 5 MPH front, and 2.5 MPH rear. Since the average speed at which accidents occur is 30 MPH, the only thing the 5 MPH standard did was raise the cost of the average collision repair.. A number of years ago the NHTSA reduced the standard for front bumpers to 2.5 as a result.

Ford motor company is the only manufacturer that still builds to the 5 MPH standard for front bumpers. Ford also is the only manufacture that built to exceed the NHTSA full frontal and rear crash standards, by 5 MPH. Ford builds to a 40 MPH front, and 35 MPH rear collision, protecting properly belted passengers The Interceptor is built to a 50 MPH rear standard to maintain the integrity of the fuel tank, as well

The 'Bumper' they run into is NOT the standard bumper height set by the NHTSA. They reason that since those vehicles not subject to the NHTSA standards, often have slightly higher bumpers, they choose to test against a 'bumper,' that they represent as what they believe to be the AVERAGE bumper height. It is HIGHER than the NHTSA standard If you look videos of their crash tests, you will notice the collision occurs just above the bumper, not in the center of the bumper, of the vehicle being tested. The result is the bumper is pushed down, out of the way, and the grill area takes much of the hit.

The only, repeatable, valid crash tests one should rely upon are those established by the NHTSA

mike

I bet it is possible to both increase the crash-worthiness that the law requires (e.g., increase the speed to say 5 mph) and to meet the requirements without adding a lot of weight or cost to the vehicles.

Jeff

In the real world cars a developed to absurd the forces of the collision, to protect properly belted passengers, not to reduce damage to the vehicle. What would you prefer a car that receives less damage in a collision, but you get killed or injured?

mike

I think is you were in a collision with a 2007 Corolla, you would change your opinion of which you would rather be a passenger ;)

mike

But it is possible to make a bumper that doesn't begin to absorb forces until say 10 mph. Or absorb them without damage in such a way that injuries are increased. (Kind of like light posts are breakaway so that they don't cause injuries in a high speed crash).

But, I guess the question comes down to what are the benefits to doing this?

I think Mike is right that this is all hype and unreliable data.

Jeff

In the automobile industry, "crash worthiness" generally refers to protecting the occupants during a crash, through crumple zones, reinforced materials, and restraint systems. Ironically, to make a car safer for the occupants, a greater part of the car outside of the passenger compartment has to deform.

The problem with insurance industry testing is that they always test beyond standards. If the federal standard was 5 MPH, they would test at 7.

Bluntly: I wouldn't trust "Mike" to right on anything. He'd want to twist it some way, if only for the sake of twisting.

I saw one of my posts jumbled up with yours and "Mike Hunt(er)"'s thanks to top posting and can't make out who said what, when. So I'll just point out that the Volvo I saw HAD protected the driver by crumpling its front end; but the crumpling had been limited by design so that repairs were easy -- just replace the crumple zone by disconnecting it at the designated points. Or that was what I gathered from the one I saw and the garage bod's remarks.

Can't help thinking things could be made easier by some long hard thinking on how to extend the above principle. Perhaps design in a series of crumple zones, which deform by turns as impact energy increases? The primary zone, for (say) 0..5mph could be a bumper constructed cleverly with burst chambers, like those water tubs a USian overpass is often protected by, but moulded into the bumper as sealed air cells. The thing'll be toast anyhow; recyclability of the mashed materials could justify elaborate tricks that avoid mixing material types. (AIRY WAVE OF HAND) Details, hey?

Is the Interceptor built to a higher standard than the non-Interceptor Crown Victoria? Is it done with race car style fuel cells?

I like the segmented idea, however, I don't know how consumers would accept a vehicle with additional lines or segments in front of the A-pillar or behind the C-pillar.

Taxis and buses in the U.S. had bumpers with burst chambers for a while, and they were pretty ugly, with the appearance of the bumper on an amusement ride bumper car. They seem to be a practical solution where style does not matter, but like a good meal, presentation and appearances count for a lot with U.S. consumers.

yes, this was implemented after numerous police cars exploding after being rear ended at traffic stops

There have been some significant advances in bumper design, but it appears most of them have gone by the wayside in favor of "style"...

The Saab 99 and 900 models from about 1974-1983 had front AND rear bumpers that not only withstood impacts, but did so without incurring significant (other than purely cosmetic) damage to the bumpers themselves as well as the rest of the car. My first Saab, a '74 99EMS, had 5 mph bumper front and 2.5 mph rear. The '82 900Turbo I had until 2 years ago had 5 mph bumpers on both ends. Both cars had been hit several times, resulting in nothing more than a shallow impression in the rubber cover or a crack in the plastic trim strip embedded in the bumper face.

Alas, even Saab succumbed to the "style" trend. My wife hit the corner of the garage one day in our '94 new-generation 900, at a couple mph. It cost $1000 to fix the car, and no damage to the house!

It really is a shame that the industry HAS the technology, but refuses to use it...

They are not mutually exclusive. From the mid 70s to the mid 80s Saab managed to engineer bumpers that protected themselves AND the car at low speeds, and "crash zones" that allowed the car to sacrifice itself to protect the passengers in a high-speed crash. After the mid 80s, the self-repairing bumpers went away, but the crash zones remain.

In my '74 99EMS I had a head-on with a pickup that tried to do a left turn in front of me from the opposite direction. Pickup was totaled, Saab had $1500 damage (significant back in '76), only injury was a bruise to my passenger who didn't have his seat belt on.

Thanks for the kind words ;)

That is pretty much how the current bumpers ARE designed to absorb minor impacts, using plastic air pockets. At some point, as the forces are greater, the piston absorbers, that connect the bumper to the chassis take over. If that happens the parts can and must be replaced. After the bumper has done what it was designed to do, the vehicles designed crumple zone must do the job of absorbing the forces of the collision. If they fail to absorb enough of the forces, quickly enough, even a properly belted passengers can be injured or killed when one organs strike ones skeleton

What I tried to point out was the majority of collisions occur at greater speeds, so the bumper becomes moot The problem with their tests is the fact they do not fully strike the bumper, thus making other structural parts take the brunt, NOT the bumper, leading to greater damage to the vehicle than would occur if the bumper was struck fully.

mike

Only the P71 CV is design to 50 MPH, other are 35 MPH. Fuel cells are an option on the Interceptor only, as far as I know, since they are not listed among the free standing options for the CV/GM..

mike

I supose one could buy the Interceptors 'Push Bar' from Ford parts and put it on one CV/GM if they wanted ;)

mike

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