Canada is the only country in the world that has 5mph bumpers (and one
of only TWO countries in the world with any sort of bumper standards at
There are no hydraulic rams anymore, just styrofoam atop a rigidly-
mounted steel beam. The rams were too heavy and were a casualty of CAFE-
derived weight-saving measures.
The whole point of the energy absorbing bumpers was to protect the car's
"safety systems" from damage in a collision at that speed. "Safety
systems" primarily means the headlights.
The automakers were able to have the US standard reduced in the mid-'80s
because they were able to show that there wasn't much practical
difference in damage between 2.5mph and 5mph bumpers.
2.5mph bumpers were supposed to be able to be less costly to produce and
carry less of a weight penalty.
Also, rigid bumpers tend to carry more of the stress of the collision to
the body shell, meaning damage is more likely to go deeper than just the
cosmetic. The old non-impact bumpers tended to keep the damage out at
the cosmetic sheet metal.
also a crock. whatever the propaganda that was used to rationalize this
downgrade, it came down to one simple thing. corporate welfare.
5mph bumpers meant that the usual parking lot dings and bumps weren't
causing damage, thereby causing a sudden and substantial loss in revenue
for repair shops, and most importantly, manufacturers. so it was
reduced, with b.s. reasons cited like you say, but they're untrue.
and "deeper" damage, is by design, not accident. the initial yield
point of a crumple zone is easily designed, as is the point at which it
occurs. frod are ruthless exploiters of this. where's the first point
to buckle behind the bumper at 5mph on frontal impact? the bit /behind/
the radiator perhaps? no. the bit in front of the engine perhaps? no.
the bit behind the engine and suspension, where repair becomes
uneconomic? youbetcha. a necessity of design? no way. profitable?
indeed. and they reduced write-offs substantially too. not as
profitable to detroit repair as it is to sell a new car.
Consider the collisions you have known. Some of them have been at very low
speeds - parking lots, creeping traffic that suddenly jolted - but the rest
have probably been at much more than 5 mph. Except for the 1-2 mph dings I
can't think of a single collision I've ever witnessed that was under 15 mph.
Proposed bumper height standards were the rage for a while because bumpers
are pointless if they aren't used. Dunno if any standards were actually
passed. The big problem there was (and is) that rear end collisions are
notorious for bumper heights not matching. Each car in line nosedives as it
brakes, so the lead car raises its rear bumper and the following car lowers
its front bumper.
you can do a lot of damage even at that speed. the thing is, what are
the /relative/ speeds. if i'm braking and am at 45 the moment of
impact, and the guy behind me is doing 55, relative speed is only 10.
that's a very common scenario. the dangerous ones are trees and
bridges. they're doing exactly zero mph when you hit them and are
that's a hot button topic. there are indeed bumper height standards,
but highway patrol never enforce it. as to dive, most modern cars have
anti-dive geometry so it's not the issue it may have once been. maybe
perpetuating the myth that "dive makes bumper height enforcement
pointless" is the deal with the hp.
yes,the VW Golf that rear ended my 94 Integra nosed under my bumper and
struck the exhaust system,bending the pipe at the "zigzag",and only
damaging the bumper cover where the license plate mounted.
the VW had far more damage to it's nose than my Integra had to its rear.
Now,if it had been a full-size SUV,I'd probably have been crushed when my
roof caved in....when the SUV climbed over it.
On Mon, 16 Jul 2007 20:39:58 -0700, Michael Pardee wrote:
But a lot of carmakers, esp the Japanese, responded quickly and designed
the *car* around the *bumper*.
My 1978 Corolla looked kind of awkward with these big bumpers 'tacked on'
to it, the 1980 that replaced it was nice!!
I don't think nhtsa has any weight or material requirements.
Maybe there are damage-at-speed requirements or even just ratings that
would make the composites look bad, until and unless a whole lot more
engineering was done as I suggested, with modular replacement.
Never look to the government to help, though they can always get in
the way, I just don't know what might be in place right now that's
damned straight! a good deal of the modern so-called "safety" agenda
does little more than add massive weight to a car, and thereby ruins gas
mileage. now, how many oilco lobbyists are there in d.c? a good deal
more than there are engineers experienced in matters of vehicle design
and safety i'll wager.
I would like to know how much of that weight is specific to the
side-impact standard that simulates getting hit by an SUV. Hey I got
a better idea; why don't we require the SUVs to carry a big fluffy
bumper so they don't inflict as much damage? And while we are at it,
let's require all light trucks to be painted pastel pink. Then we
will see how many people *really* need a truck.
to meet the side impact standard,auto makers raised the height of the door
and bodywork(to keep another vehicle from hitting the weaker window
area);note that today's autos are taller than earlier models.
AFAIK,Audi and Acura are the only automakers to make an aluminum body
auto,the Acura NSX is aluminum.
IMO,more auto body components could be aluminum,saving some weight,and not
rusting,either,although Al to steel will corrode without special
not true for all new vehicles:
this thing cruises in at under 2,000lbs too.
adds to the price too.
bottom line, i think safe is good, but the weight penalty to "protect"
against side impact, the current hot ticket, is pretty much pointless.
any time you have your head right next to a nice inflexible piece of
bodywork, and no distance in which to decelerate moving objects, you're
going to have injury. period. racing bucket seats, 5 point harness and
helmets otoh /would/ make a significant difference to side impact
safety. but they weigh nothing. just wait another 30 years and see
whether they become mandatory! [not.]
Aluminium? (love the British version) Nah. Plastics, my man, the
high-tech ceramics. You don't see any aluminum tennis rackets now,
the composite materials are ridiculously stronger and lighter (and
cheaper!?), and they're going away from aluminum to composites now in
the aircraft. Aluminum fatigues and fails, so it has to be (mildly)
The new 787 is largely constructed of carbon fiber.
The first big aerospace application was carbon fiber rotor blades that
were pioneered by Kaman in the 1960's. The company is the world's
largest producer of rotor blades today.
OTOH, the L1011 while sporting an aluminum fuselage had no stringers as
it was constructed of thicker aluminum sheets which in turn really
provided for an airframe that did not have a dated life time expectancy.
Construction and maintenance were greatly simplified.
Well, since we are talking anecdotal mileage, I should report that so far I
have averaged 35.69 MPH with just over 1065 miles. I have a Fit Sport 5
speed manual transmission. I'm always conscious of driving for economy, and
I try to time the stoplight, whenever possible and practical. I am more than
satisfield with my mileage, but it would be less if I drove with a heavy
foot. Consumer Reports averaged 34 MPH overall with their 5 speed.
Robert A. Cunningham
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