Ok hate to be the one to mention this but....
If you sleeve your frame in that spot it looks like you will be reenforcing the Crumple Zone. Not exactly a good Idea, that could cause your air bag to prematurely deploy in an accident. Or deploy when it normaly would not have. The sensor for the air bag requires so much "shock" to set it off. If the frame doesent crumple in a lower speed accident you could inturn set of the air bag.

I dont claim to be an expert on this but it is just an Idea. Personaly I wouldn't screw with the acordian looking part of the "frame horn".

As a matter of fact Im gonna ask my Body shop buddies how that would affect that. It could be there just to save the frame but some how I doubt that.

Ok I talked to my friends that work in body shops. If you sleave and reenforce the crumple zone on the frame you could cause the air bag to go off in a accident it normaly would not go off in. This in turn could injure you. SO do not reenforce that part of the frame.

Possibly, yes, but the airbags work on inertia and there is a sensor up front, behind the grill, but most of it is controled by the computer under the arm rest. If the frame horns are reinforce, it may make some difference, but not so much that it would concern me.

We went through that scenario on the jeeps and their reinforced bumpers...

The decelleration rate is what sets off the bags sensor's...and the sensors are not on bumper or horns...

Essentially...when I run into a 120 lb deer at 50 mph, if the truck doesn't slow down fast enough "Suddenly" for the sensors to assume I hit something that will make me slam my face into the dash hard enough to ~ die, they don't trigger the bags.

If I hit a wall, or the back of a mack truck, etc...and the truck is actually slowing down suddenly enough -Suddenly stopped-, BANG! the bags go off.

The crumple zone can slow the process a bit by allowing the truck to stop slightly more gradually, but we are talking about a few inches...and its not like the sleeve/reinforcement is likely to support the force = mass times acceleration.... involved with that type of collision.

On jeeps at least, it doesn't seem to make enough difference to matter...and my worst impacts in the X were deer, not mack trucks, and ~100 to <200 lbs between 25 and 55 mph...and the bumper didn't budge, the frame horns didn't crumple, the deer pretty much absorbed the impact and transformed the involved energy into venison puree, etc.

I need to improve my lighting....might avoid more deer that way...

:rolleyes:

If I hit something hard enough to matter, I'll report back if the bags went off...otherwise...

.... I'm with Dagger, It doesn't seem to be enough difference to matter.

i wanna see this puree.

Its nasty....you don't really want to.

This is why I ended up buying the TJM.

While most bumpers only connect to the horns:


The TJM has a piece of 3/8" plate which connects the brackts to the frame tiedowns:



It may not look like much in this picture, but it is a beefy piece.

In my opinion, this results in much less stress on the frame horns.

I think the differences that you see will come at low speed collisions. More than likely if you hit something at 50 your airbags are going to go off, but if you get into a minor fender bender they shouldn't.

Yes it is a shock/deceleration censor. I have had someone back into me REALLY HARD!!! If it was not for the bumper it would have been really bad. TY ARB BUMPER!!!!

I say armor the hell out of it, drive safe and let all the idiots pay the price!!!

The sensors/airbags will act fine if you get into a real accident.

To further clarify what the ramifications are, this picture shows the (3/8") frame tiedown plate used by the TJM:



.

This gives the bumper 10.5" of connection distance between bolts as opposed to about 6" in a horn-only connection. The following diagram show numbers for a simple analysis:

Would having a front skid plate on give the bumper anymore strength? Assuming it is connected to the bumper and somewhere else on the frame.

Good illustration Jeff.

The ARB has wings that come back for the same purpose....we end up cutting them off when we do the BL's as there's no way to retain them when raising the bumper.

I like TJM's bracket that wraps the rails though, Brent's was pretty sturdy looking for example. I'm not sure how it would be retained if lifted...but, like the ARB's, you can always go to a fab shop and have them reinforce after the lift.

Thorsen -

A front skid that connects the front bumper to the front cross member would tend to reinforce the set up relative to horn distortion, and if butted to the cross member and bumper, act as a brace relative to downward or backward motion as well.

If not butted, the shear forces would be absorbed by the bolts themselves, rather than braced by the structural elements, and would not be as strong in that direction, albeit stronger overall than w/o the skid.

im planning on buy a 2" BL, which bumper do you guys recommend me to get after noticing these problems? thanks!

They are all good. I have both the Shrock and the ARB. The Shrock is a much better built bumper, IMHO. Whatever you get, make shure you torque the bolts correctly and check them periodically. Adding a few bolts to the Shrock doesn't hurt, but I have never had a problem and have yanked the hell out of my Shrock bumper. I think the problem is a few isolated issues.

Yeah - Dagger's right, they are all stong enough to pull with, even the ARB.

The extremes of force Jeff is illustrating involve what happens if you put a heavy load ON TOP of the bumper, pushing it straight down.

This is relevent, as some pulls involve the nose of the recovery X being higher than the recovered rig, so the X's nose gets pushed down by the pull....not straight down with the full load as shown, maybe a matter of 45º though, which perhaps ~ halves those numbers....and, if the bumper is lifted, increasing those numbers proportionally, as the height obove the frame rails does increase the forces as leverage increases, etc.

W/o doing the math, raising the bumper 2" would have less affect than going from 45º - 90º pull angle (If 90º is straight down, and 180º was straight ahead, etc.)...but it would be a measurable difference.

So - as far as I can tell, ALL of the bumpers mentioned can pull at their rated loads...some have higher/lower ratings though.

The difference in abilities seem related more to other factors, like front or side impact resistance, approach angle, quality of finish, weld through vs weld on construction, aesthetics, preferences for hidden vs exposed winch mounts, welds vs bolts, etc.

Deer for example are a severe test of any bumper...as the bumpers are braced against a winch's pull rather than a deer's push, etc.



The X's frame horns are not rock's of Gibraltar, and when I lifted my bumper, I welded a brace between the horns to compensate for the leverage extra forces from the raised winch point relative to the frame horns.

Its held steady, with no sign of torqueing, but I noticed that my exposed horn ends are taking a beating in rock gardens...so I plan on getting around to boxing in the end of the exposed horns with a decent piece of angle iron I found.



I never got around to installing a plate from the bumper back to the leading front plate, and frankly, there's not a whole lot of vulnerable stuff between them given the horns and brace to shield them....but I might do one to the new angle iron back if I ever have enough free time again....

:rolleyes:

Actually, these forces are calculated for straight ahead, as in the case of winching or pulling from recovery points on the front of the bumper. And these are very conservative estimates because I included the taps in the front of the horns in the 6", which are nonstructural connections. Realistically, those points will withstan very little, putting the stress on the remaining two bolts.

These numbers are rough, but do reflect the ratios of the two different designs.

EDIT:

You have dismissed these plates as being something that will simply be "cut off" in the event of a body lift. A body lift serves no purpose on my truck, as I plan on clearing 35s without one (like Rondo). So these plates will serve their purpose until I get a different bumper.



Where do you see trimming in this pic?

Ron's rig is proof that you can put 35's on a Fronty or Xterra with little or no trimming. I've seen him totally flex out that suspension with no rubbing.

Jeff - yeah, the only purpose of the BL is to clear larger tires, and if you can do it with a Sazall, etc...there's no point in the BL.

I wonder what he did then, every one else has rubbing...

Little or no trimming...?

Maybe removal of all well plastic ...or stop extensions?

Seriously, are there pics close up of the detail....it sounds like a real break through in wheel well clearance....

And, I LOVE clearance.

I'll be ALL over THAT mod this week if I knew what he did.



PS - I didn't diss your plates...I discussed ARB and TJM tie downs and the BL solutions, including just having something fabbed up...

How'd I know you could fit 35's w/o it?

He SASed with over 6" of lift.

EDIT:
The picture clearly shows that his plastic trim is intact.

OH - OK.

So he keeps the stuffed up side tire from coming up too high when the down side is drooping by doing what?



This is SAS stuff that's different from "just comes with front live axle stuff"...on my jeep situations, I needed to BL to make room for the upside stuffed tire to swing into when the opposite side was fully drooped, like what you'd get on an RTI ramp/big rock, etc.

This SAS stuff will be new for me.



How's it work?

Not to point out the obvious, but a bumper is supported by 4 bolts not 2, so your forces should be halved.

whats the difference between all the bumpers?
I really like the ARB bumper, but it seems that the shrockworks one is alot stronger in general. If i were to get the shrockworks bumper, what is it exactly you guys recommend me doing. You were saying something about adding a bolt?

Good point. The forces listed on the diagram are supported by 2 bolts each. The ratios of forces on the two configurations remain the same.

There are plenty of differences between the bumpers.

Calmini and Shrockworks both have thicker metal than ARB and TJM.

There are differences with bracketry, the tubing up top is different with all 3.

There are pictures of all 4 here:
XOC Thread

I think that all of these bumpers are very useful. They are all well-designed and tough. Calmini is still my favorite for the open winch mount. Years of recoveries in the Army have taught me that it's nice to be able to get to the winch to troubleshoot if necessary.

I know people running all of these bumpers. Most people seem satisfied with theirs. No bumper in the lot is perfect.