Stock Bumpers Stink

I took off my rear bumper last night so I can sandblast it and paint it. I was really disappointed in the stock bumper mounts. Two bolts into the actual mount, then two bolts into clips - that's it - and one of my clips broke just trying to back out the bolt. Can't imagine it in a collision situation.

What were those guys thinking? :doh:

All four of my 'nutcerts' broke when removing my front bumper. They were designed for speed of installation at the factory and nothing else IMHO.

I replaced them with real, genuine, non-imitation nuts with lock washers.

keep in mind that from a manufacturer perspective, the function of the bumpers is to absorb collision energy and they do this by bending, folding, collapsing. The job of the bumper is to break in a collision and it is designed to do this so that it protects the impact energy from damaging the rest of the vehicle.

I am in the process of building a new 'stout' bumper for my xj and when I look at the sturdy mounting plates I have built I can see that now, if I have a front end collision my xj will be a write off because the bumper and mounts will not deform and will transfer the energy directly to my frame rails which will deform.

In short, the factory bumpers are great for their intended purpose. It's just that our intended purpose, as avid 4x4ers, is different than what the factory had in mind.

Do you think a big strong steel bumper would set off the airbags too soon, or too easily?

I would be only guessing, but I think that the airbags are triggered by some sort of pendulum? spring loaded? electronic sensor? device that measures how rapidly the vehicle decelerates. If you have a low speed collision and your bumper is collapsing, your rate of deceleration will be slower and the airbags may not trigger.
However, if you have a really solid bumper that doesn't collapse the vehicle will stop NOW (very fast rate of deceleration)and that could trigger the airbags at lower impact speeds than they were designed to trigger at.

fuzzydog said:

I would be only guessing, device that measures how rapidly the vehicle decelerates. If you have a low speed collision and your bumper is collapsing, your rate of deceleration will be slower and the airbags may not trigger.
However, if you have a really solid bumper that doesn't collapse the vehicle will stop NOW (very fast rate of deceleration)and that could trigger the airbags at lower impact speeds than they were designed to trigger at.

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Kinda sorta and yeah, the decerloration is a large part in the airbag system. In XJ's the steering shaft/colum is where some sensors are and is designed to "crush" setting off the bags. At the same time there is a limiting speed, so in low speed impacts there will not be deployment. Having a aftermarket bumper will cause a ripple effect in the unibody "rails" but if you hit that hard you'll be glad you had the burly bumper.

The XJ is unibody, bumpers are for looks, there is nothing to fasten anything heaver too anyways.

Do you think a big strong steel bumper would set off the airbags too soon, or too easily?

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I was just reading that ARB puts a lot of effort into making sure their bull bars still allow the airbags to deploy as designed by the manufacturer. I'm not sure what the difference is, but if you're concerned about daily driver style safety, that might be a consideration in your purchasing decision.

Well, I don't plan on getting in a head on collision if I can help it.

I'll do anything to avoid a head on, including rolling the Jeep or going completely off the road.

We often forget that the most important safety feature of any car is the DRIVER.

After repairing my front end from the previous owners misfortune, I too was super sensitive about head-on collisions and agree with the driver being an important part of safety. Then sitting at a traffic light on a rainy day, a Dodge Dakota rammed me in the rear and totalled my xj for the second time in six months. If I had been watching my rear as much as I had been watching the stopped trailer in my front could I have moved out of the way? Or would that attempt at moving put me at fault? Or greater danger? Who knows? Truth is we have no control over much of anything when other humans are involved so just beef up your front, your rear, and your insurance coverage. Then go to church, any church, can't hurt.