Bumper modification legal and safety issues?

[getout]

So, maybe this is how you can tell I'm coming of age, but this question popped in my mind:

What are the legal and safety issues with bumper modifications?

I know a lot of factory bumpers/frames come with crumple zones and most are at a height so other cars don't drive underneath them, but what about modifications? Are there legal restrictions to slapping a bunch of steel to the ends of your car if it compromises those things?

I'm in the Utah in the U.S. and I'm sure there are different laws everywhere but it seems like the safety part would be universal.

 

[dustboy]

Jonny Law really only cares about mudflaps, lights and tags. Even with height, you probably won't get called on it, because there are a lot of trucks out there lifted 12"+ without lowered bumpers.

Safety-wise, it's hard to say what difference the bumper will make for you. In my opinion, a heavy steel bumper is better than a flimsy plastic cover. You do give up the 5 mph bumper concept, in a low speed impact you may end up damaging your frame rather than just the bumper.

People will tell you that you need to buy a certain bumper (e.g. ARB) because it's airbag compatible. I think that's just hype.

 

[ThomD]

Here is some interesting info on bumpers.

http://www.nhtsa.dot.gov/Cars/Problems/studies/Bumper/Index.html

Short answer - largely unregulated on SUVs and trucks.

 

[OTR]

I don't really worry about, more steel equals more safety IMO. I figure that if I hit someone there is a good chance I'll drive my truck home and not have to worry about too much damage. I have full coverage insurance so if the frame is bent I can get a new truck I guess. I was always worried about even hitting a shopping cart with my painted plastic bumper, now just I push them out of the way.

 

[getout]

I guess I was thinking safety for other drivers. Do you think someone rear-ending you would have a solid argument in court that your bumper was too high or too strong and compromised the safety of others?

 

[getout]

After reading this I may retract my entire thread.

From the NHTSA site:
"[Bumpers are] not a safety feature intended to prevent or mitigate injury severity to occupants in the passenger cars."

 

[goodtimes]

After reading this I may retract my entire thread.

From the NHTSA site:
"[Bumpers are] not a safety feature intended to prevent or mitigate injury severity to occupants in the passenger cars."

But the argument could be made that since you modified the vehicle in such a manner that prevented the 'crumple zone(s)' from working as intended, your vehicle transferred more energy into the vehicle that you hit, which had a negative effect on the occupants of that car.

In short, your crumple zone doesn't absorb energy, which means that the other vehicle has to absorb more. In this aspect, it does not prevent or mitigate injury to the occupants, but it may cause injury to others.

I have no idea how far that argument would go in court . . . but it can certainly be made.

 

[java]

i know in WA there is a code for the height of the bumper, dont remember the number off the top of my head, but it doesnt say anything about material.

 

[Rando]

I don't think this is necessarily true. In the case of a low speed "fender bender" you maybe better off with a rigid bumper and frame. However in a real life or death type of accident, you would be better off with the factory bumpers (and less steel). The thing that kills you in an accident is deceleration (well trauma actually, caused by rapid accelerations). Think about it in terms of simple physics, if you hit a concrete wall at 70 km/h (20 m/s) and your car deforms by 1 meter (allowing you to come to a stop over a distance of 1 meter) the acceleration is on the order of 200 m/s2 ( about 20 g's). On the other hand if you have a very rigid bumper directly tied to a very rigid frame, and your vehicle only deforms by 20 cm, the accelerations are of the order of 1000 m/s2 (or about 100 G's !) . Obvously it is not a simple as that, but you get the idea.

I don't really worry about, more steel equals more safety IMO. I figure that if I hit someone there is a good chance I'll drive my truck home and not have to worry about too much damage. I have full coverage insurance so if the frame is bent I can get a new truck I guess. I was always worried about even hitting a shopping cart with my painted plastic bumper, now just I push them out of the way.

 

[cruiseroutfit]

Utah law on bumpers:

"Utah Code
Title 41 Motor Vehicles
Chapter 6a Traffic Code
Section 1632 Bumpers.


41-6a-1632. Bumpers.
(1) A motor vehicle shall be equipped with a bumper on both front and rear of the motor vehicle, except a motor vehicle that was not originally designed or manufactured with a bumper or bumpers.
(2) (a) On a motor vehicle required to have bumpers under Subsection (1), a bumper shall be:
(i) at least 4.5 inches in vertical height;
(ii) centered on the vehicle's center line; and
(iii) extend no less than the width of the respective wheel track distance.
(b) A bumper shall be securely mounted, horizontal load bearing, and attached to the motor vehicle's frame to effectively transfer impact when engaged.
(3) If a motor vehicle is originally or later equipped with a bumper, the bumper shall:
(a) be maintained in operational condition; and
(b) comply with this section. "

But they have a general disclaimer that anything you do to modify a vehicle must not detract from its safety. IE if you build a bumper that alters the deployment point of an airbag (be it make it fire too soon or too late) you are liable for the injuries that result.

 

[dustboy]

I have full coverage insurance so if the frame is bent I can get a new truck I guess.

I wouldn't assume that, unless you've told your insurance company about the aftermarket bumper. They will find a way to weasel out of paying. It's their job...

Which reminds me, I should call my agent.

 

[Mr. Moore]

I would start with asking your insurance agent and checking with state and local laws.....most states don't seem to care about bumpers....but your insurance might. I would hate to find out the hard way that your insurance won't cover a total because of the bumper. I don't see why it would matter, but you never know. If it isn't an issue withinsurance i would say go for it! stock bumpers tend to suck anyway...:smiley_drive:

 

[Martinjmpr]

"crumple zones"

As I understand it, the only cars that have "crumple zones" are cars with unibody (monocoque) construction, where the frame and body are integral.

Since most of our trucks and SUVs have body-on-frame designs, they don't have "crumple zones" anyway.

 

[robert]

That Utah code is interesting with it's inclusion of:
(iii) extend no less than the width of the respective wheel track distance.
Given the number of Jeeps I've seen out there with short bumpers to allow for rock crawling I'd say it's not enforced.

Vehicle with frames usually have some sort of crumpled zones also- some in the form of crush cans behind the bumper (ex. the corrugated looking bumper mounts for the Tacomas) some in the form of subframes that sheer and slide inside the chassis frame, etc.

 

[OTR]

Vehicle with frames usually have some sort of crumpled zones also- some in the form of crush cans behind the bumper (ex. the corrugated looking bumper mounts for the Tacomas) some in the form of subframes that sheer and slide inside the chassis frame, etc.

This is true, I was able to maintain these with the installation of my aftermarket bumper. I also believe that there are crumple zones built into the frame itself.