You and me both <img src="/forums/images/graemlins/rolleyes.gif" alt="" />
I just remember the massive chrome 5-mph bumpers on my parents 1973 Country Squire wagon (the car that was the inspiration for the "Family Truckster", I'm sure).

I don't think that is a problem as long as you are within legal height off the ground...there is no rule against steel bumpers, they just don't want your bumper so high off the ground that a car can submarine under the bumper and the bumper intrudes into the passenger compartment.

My opinion is the mass and velocity of what hits you in the back is more of a factor to your occupant's health than the design of your bumpers. I just can't see even a modern bumper absorbing even 20% of the crash forces. I could be wrong though. I'm not talking about cars with crumple zones built in. I'm just saying the bumper design itself.

You could have 10" steel spikes sticking out of your bumper and it wouldnt matter. As long as you didnt do something stupid like cut them off then slam the brakes, they will be considered at fault if they rear end you.

I heard a couple weeks ago that the safety nazi's are at it again. They are trying to make car makers put anti submarine bars on trucks and suv's that have bumpers above a certain height. Basicly like they have on the back of 18 wheeler trailers. I can see alot of those getting cut off quickly.

Personally I'd rather have a big steel bumper then a plastic one. Can save the body and even if the frame does get tweeked it can be straightened. Which is why I only buy something with a frame, I dont want a fold up car.

Okay, first off, Physics:

I'm an EMT for my county, I've responded to hundreds of MVAs (motor vehicle accidents) and seen different variations on what the energy transferrence in a wreck can do to what man creats and operates at what he/she thinks is "safe".

If you take a standard vehicle of today and throw it down the road at 70mph and decided to come to a sudden stop, you'll strain against your seatbelt cause your body is still travelling 70mph while the car is going slower....if you hit a tree you will still be going 70mph, but your car is now doing 0mph. Thats alot of energy you have built up! The seatbelt, airbags, doughnuts, 32oz drink and your friggin' cell phone do NOT eleviate your suffering during all this. <img src="/forums/images/graemlins/ignore.gif" alt="" />

But I digress. If you are trailriding or rock crawling, the strong bumpers and sliders are a benefit of protection allowing the truck to hit or rest upon the frame instead of damaging a $1500 bumper or fender!

Now, Morals and Ethics:

During your trip to the milk store at 35mph you see someone swerve in front of you to make that quick turn before you get there....the passenger side of car #2 is presented to the 100#, 3/4in steel jaw of your 4x...there is NO give in your bumper when it meets sheet metal and the frame of the windsheild and door of car #2...even less resistance is there in the passenger in that seat. Your bumper is in good condition except for some scratches and mixed bodily fluids of the person with bad choices when it came to who to ride with that day.

Are you wrong for your choice in protection? Was car #2 wrong for pulling in front of you? Would an OEM bumper have transferred the energy differently, allowing your vehicle to crumple as well, and allowing the car #2 to retain it's structural integrity enuff to not shear the passengers head off his/her neck?

<img src="/forums/images/graemlins/shame.gif" alt="" />

Rule 1 of EMS and Law Enforcement
~Whatever happens out there, YOU go home at the end of the day~

Good luck on your decisions with your Mods Oleg. I understood your original question of the energy being transferred to the occupants of your vehicle having the mods. I can see that as possible. Best answer: Don't drive it. Or don't drive it with any humans inside. But that's not reasonable or any fun, now is it? <img src="/forums/images/graemlins/smile.gif" alt="" />

Dana

Best bumper sticker:
"Your vehicle is MY crumple zone"

yeah, it leaves me not much choice with whom I can drive... most of my friends and almost all my relatives are humans (to some extend)...

Good post,I personally believe to mount it solid and make it strong.

As to the bending the frame,If the impact is great enough to bend the frame I don't want to be in it when it happens <img src="/forums/images/graemlins/scared.gif" alt="" />.

Also if the frame get's tweaked alittle and the rest of the vehicle actually survived'd the incident,then i say poo on it and drive.As long as the bend is behind the front axle frame mounts and the links are ok it will drive good even with a tweak'd rear frame.
Unlike leaf sprung vehicles where alot of tweaking happens between the spring mounts....causing it to crab.

I want my bumpers to not move and crumple why?Because the more they can crumple,bend etc. means the main force to the blow can be directed at the body,and sheetmetal ain't gonna slow down 4000#.So if my 100# of steel can slow down a vehicle before it folds itself into/onto my body,then <img src="/forums/images/graemlins/cheers.gif" alt="" />

Sliders can help also,if they stick out past the body.I was hit in a parking lot by a lady,not fast but I guarentee that the doors would not have been able to open without the sliders----and yes it tore up the front of her car.
Now if she would have been going alot faster It would have flipped me over,that I'm sure,but the initial impact would have been the sliders and not my pelvis.

Bansil's .02 for the weekend <img src="/forums/images/graemlins/patriot.gif" alt="" />

I want my bumpers to not move and crumple why?Because the more they can crumple,bend etc. means the main force to the blow can be directed at the body,and sheetmetal ain't gonna slow down 4000#.

For multiple reasons, I also think bumpers should be stout. But, we can save that discussion for another day.

But, what Doug said above is not quite correct. The more stout and more structurally integrity a frame/vehicle has, the more force is transferred to the occupant. If the vehicle does not deform, the passenger is left traveling at the original speed and is often rudely stopped by the seat belt. Not to mention the internal organ bruising caused by them bouncing around in their own confined spaces.

Crumple zones and the ability to deform absorbs the energy of the impact. Crumple zones are there to save the passengers, not the cars. The general thought is the value of the vehicle is less than the value of the humans within. Some may argue, but...

That said, can we really make a difference in the overall engineered design of the vehicle? No. At the far extreme of impacts, whatever we bolt or weld on will fail at that mounting point. And, at that point, we are beyond saving the vehicle anyway and just hope ourselves are OK. I really doubt any aftermarket bumper has made the difference in a head on or other high energy crash.

The up side is that what we add to our vehicles as protection from the rocks often does the simple task of saving the sheetmetal (or plastic, depending on your variety of Isuzu). That, in itself, is enough of a monetary benefit for all of us to agree with.

Parking lot lunatics, low speed impacts and even rough shopping carts are all less of a worry. Although, beware, this only stands true if you are not the one at fault. If you rear end someone, your bumper may cause more damage, but I doubt it would be significantly more than without it. But, at that point, it is between you and your insurance agency.

Good Luck,
Michael

If your really worried about it you could put smaller bolts holding on the bumper. That way in a big accident they could shear. That would work right???

these are all inherant problems you face when dd'ing you wheeling rig. if it bothers you, get a safer dd, and save the zu for the trails.

for those of us driving older vehicles, we are VERY far behind current safety standards. so i look at it like this, if I get rear ended, my big steel bumper will possibly keep that vehicle from smashing/rupturing my gas tank and setting me on fire. if there vehicle gets a little more banged up or i get bruises across my chest and whiplash, hey, beats roasting alive.

I'm a little more hesitant to put a big bumper on the front, because 9 times out of 10, anything that would involve it would be MY fault and the bumper would make things much worse for the other person.

BUT (in the case of a frontal collision) it may keep my engine from coming thru the firewall and crushing my legs and possibly paralyzing me.

trade-offs. your best bet is to save the zu for the trail and buy a honda (from me) to drive to work and the grocery store <img src="/forums/images/graemlins/smile.gif" alt="" />