This fall, I destroyed my rear bumper on a trail and I had to replace it with something. I decided to go with a steel custom bumper from a small local fabrication company http://www.bentup.com (toyota-oriented). They fabricated a good bumper for me, and I currently wear this bumper.

The bumper fits nicely and is slided directly into the frame rails. Bolt-on installation. Which makes me somewhat nervous.

The reason is that now any hit from behind would be transmitted directly to the frame (and, if this matter, to the cabin occupants). With a plastic bumber, the plastic would be destroyed, but the frame would be OK. I'd replace the bumper and everything would be fine. But now, I am risking benting the frame from any minor collision, on the road or on the trail !

I am reading on this forum that the guys are fond of sturdy bumpers. The thicker, the better. But how you guys deal with the frame ? I know that the Isuzus frames are not so strong. At least one member of this forum whom I know personally, 4Play (Ashby), bent the frame on his 2 gen Rodeo.

May be, a good steel bumper must incorporate a "soft" protective zone, in the area of attachment to the frame ?

Did anybody have this sort of thoughts I have ?

The plastic bumper is on a sheet metal frame of sorts that is bolted directly to the frame anyway...and the plastic has very little cushioning ability, it just shatters.

Back in the olden days cars had to have 5 mph impact bumpers, which had sort of a shock absorber built into the mounts, but that rule never applied to trucks.

You could always weld some old coil springs to the bumper so a low-speed impact just bounces off... <img src="/forums/images/graemlins/wink.gif" alt="" />

If you are really concerned you could weld in some diagonal gussets between bumper and frame at a 45 degree angle. About 1' long rectangular tubing. Besides strengthening the bumper, they will also resist pushing one frame rail relatve to the other in the event of a big hit. I think this all might be overkill though. My stock bumper got a few rear end hits at 5-10mph in snowstorms and the only damage was the offending vehicle. No damage to my bumper and pup rear bumpers are only about 1/16". It helped that I had a hitch providing some support. Like the other guy said, there is no reasonable alternative to not tying something to the frame. You don't want a bumper tied into the body or anything else.

CPom, I think you're missing the point. I do believe the original poster is worried that when hit, the bumper will transmit all the energy of the impact into the vehicle, and with no crumple zones, the occupants will get hit with all that energy and get whip lash or otherwise thrown about. Least ways, that's what my impression was.

Both you guys are right: I worry both about the vehicle and about the people. Having this nice bumper is good, but if there is a bigger danger to the whole vehicle (and to the occupants) then before, I'd prefer a weak destroyable/replacable bumper to my steel bumper...

You also must understand that unless you are getting hit with a solid steel bumper just like yours, (which in 99% of the cases you WONT be) the car hitting you will absorb a lot/most of the energy with IT'S bumpers that are designed to crumple.

Now, if we are talking about hitting rocks with it, then thats a different story altogether...
-J <img src="/forums/images/graemlins/kewl.gif" alt="" />

good point... Chance to be striken by a member of this board is close to zero <img src="/forums/images/graemlins/smile.gif" alt="" />

So if I worked at a firm that did FEA validation on the bumpers, does that make me olden? <img src="/forums/images/graemlins/pfft.gif" alt="" />

Trivia for the day -- the best such shocks are still in use in some cars, though most OEMs have gone to a foam or crush-cell design in front of the bumper beam all covered by tupperware. PGM (polygel mitigator) bumper shocks are single-stroke shocks that do a great job of absorbing impact.

FWIW, for off-highway use, I'd rather have a frame-mounted bumper.

Randii

I think that if you have a steel bumper on there you should worry more about someone elses ride being destroyed. Basically it was said earlier in another way. THere car is going to crumple under the impact while yours will remain with minimal damage. you are going to feel more residual energy but a low impact should not be of much concern. Either way if you get hit you are going to be feeling something.

think about the poor shmuck who you would rearend if you had a solid steel front bumper. odds are you are going to take the top off of a car that sets low <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/shiner.gif" alt="" /> I.E. mazda miata

just my 2 cents

this leads to another question: if a guy rearend me, and if his car or health is destroyed, will his insurance company sue me for having "a setup dangerous for others road occupants" ? I am afraid it's totally possible. I modified my truck to make it more dangerous to other cars, and my mod has not been approved by SAE/EPA/or whatever.