Bent Frame - Part Deux

[bleda2002]

I'd like to point out the 10 lb bowling ball to make that force would need to stop nearly instantly so that it's acceleration is extremely high. The suspension on vehicles with the shocks, trailer suspension etc would soak up the vast majority of the force before it got to the frame. Should be really easy to see if this was the case as the bump stop cups would be absolutely wrecked as that would be the fulcrum.

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[Hootbro]

Reminds me of two kids caught fighting. You only get "their" version of the truth that suits them and not the actual details of what came to transpire.

 

[dcmdon]

if they're saying nogo cause of that scrape on the hitch, go buy a hitch to replace yours and then take it back in.

If the hitch hit hard and bent the frame it would bend it the OTHER way. So that's not it.

 

[dcmdon]

My wife and I were coming back from our first half Ironman with 2 bikes on the roof. My body was exhausted. My brain was fried. I was terrified that I would drive into the garage and rip $8000 worth of bikes off the roof.

I had post it notes over the speedometer, alarms set on my phone, reminders and I was repeating a mantra all the way home. "Bikes on the roof, Bikes on the roof".

ha. I was successful.

 

[Wbrook24]

Thanks again @ShadowsPapa. I know there have been a ton of discussions on this and there is a lot of chad in those threads. Appreciate the response here. Some have made it sound like if you take a trailer off-road, you will bend your frame. Seemed far fetched. Definitely not planning any Duke’s of Hazard moments in my JT, let alone while pulling anything.

Just so you know the original gladiator who bent his frame with a trailer hit a massive bump and also had shocks that were too long(meant for a lift) in the back. So that one was a real mess.

 

[Wbrook24]

If the hitch hit hard and bent the frame it would bend it the OTHER way. So that's not it.

Maybe. As the frame is designed to bend up in the event of an impact it might actually be the rebound force that does the damage. This could be why the bend is up in the middle.

 

[Rockabillyroy]

If the hitch hit hard and bent the frame it would bend it the OTHER way. So that's not it.

He said they denied this claim because of the scrapes on the hitch.

I'm not trying to figure out what caused the bend. I'm suggesting how he might get a date with the service dept. Hahaha

 

[piroman683]

Looks to me like he loaded up the bed, went “ovetlanding” and as shit jiggled around the 4 or 6 bolts that hold the bed to the frame might have settled a little.
The frame is hardened steel, and in what has been described so for, wouldn’t allow for a rebound bend. Loosen all your bed bolts, shake the bed, retorque, and move on. Lining up body panels without any measurement or actual images of the FRAME where it is bent is a useless diagnosis

 

[lrtexasman]

Wonder if similar damage would happen trying to pull someone who is stuck with a tow strap hooked to the tow hitch with max cargo weight in the bed.

 

[sharpsicle]

Wonder if similar damage would happen trying to pull someone who is stuck with a tow strap hooked to the tow hitch with max cargo weight in the bed.

That seems like a pretty specific situation. Did you do this?

 

[piroman683]

Wonder if similar damage would happen trying to pull someone who is stuck with a tow strap hooked to the tow hitch with max cargo weight in the bed.

No

 

[ShadowsPapa]

I'd like to point out the 10 lb bowling ball to make that force would need to stop nearly instantly so that it's acceleration is extremely high. The suspension on vehicles with the shocks, trailer suspension etc would soak up the vast majority of the force before it got to the frame. Should be really easy to see if this was the case as the bump stop cups would be absolutely wrecked as that would be the fulcrum.

Yes - and if you look at the formula for the force calculation there's a .25 in there, that's the distance in which the stop happened. In other words, they figured it would be stopped in .25"
You have to take that distance into account like you said.
As far as those being destroyed - not really. I used to work on a lot of IHP vehicles and they'd fly off the road across some medians and ditches, and the stops under their vehicles usually survived. In fact I saw metal parts bent but those rubber stops survived.
So many variables, and like said by others - we don't have even 30% of the picture here.
We don't have any pics of the underside, the suspension - and to YOUR point, the bump stops.............
But - we have seen pictures of bent frames that have resulted from the forces of hitting such a dip or hill with a load on the back (trailer, etc.) - it's doable.

In this case - there's a lot being left out.

If the hitch hit hard and bent the frame it would bend it the OTHER way. So that's not it.

We're not suggesting that - we're suggesting that the scrapes are a SIGN - not a cause - that there was something more involved. And I bet that's what the first dealer was thinking.

Wonder if similar damage would happen trying to pull someone who is stuck with a tow strap hooked to the tow hitch with max cargo weight in the bed.

How would that be possible? Most you'd do there is compress the springs - and likely not even bottom them out.

When I winched someone out this AM the front of my truck didn't even come down any, and his car was below my truck (but I had a lot of rope out and chain connecting my winch rope to the strap I had around his under-carriage to reduce the downward pull and keep my truck on better ground)

 

[lrtexasman]

Yes - and if you look at the formula for the force calculation there's a .25 in there, that's the distance in which the stop happened. In other words, they figured it would be stopped in .25"
You have to take that distance into account like you said.
As far as those being destroyed - not really. I used to work on a lot of IHP vehicles and they'd fly off the road across some medians and ditches, and the stops under their vehicles usually survived. In fact I saw metal parts bent but those rubber stops survived.
So many variables, and like said by others - we don't have even 30% of the picture here.
We don't have any pics of the underside, the suspension - and to YOUR point, the bump stops.............
But - we have seen pictures of bent frames that have resulted from the forces of hitting such a dip or hill with a load on the back (trailer, etc.) - it's doable.

In this case - there's a lot being left out.



We're not suggesting that - we're suggesting that the scrapes are a SIGN - not a cause - that there was something more involved. And I bet that's what the first dealer was thinking.



How would that be possible? Most you'd do there is compress the springs - and likely not even bottom them out.

When I winched someone out this AM the front of my truck didn't even come down any, and his car was below my truck (but I had a lot of rope out and chain connecting my winch rope to the strap I had around his under-carriage to reduce the downward pull and keep my truck on better ground)

The frame bending would happen far after the shocks compress due to the tongue weight (see around the 11 minute mark of the video). I would guess your winch distributes the weight where as the tow hitch centers the weight on the frame behind the shocks.

We Explain Why Jeep Gladiator, Chevy Colorado ZR2 Frames Bent - YouTube

 

[ShadowsPapa]

The frame bending would happen far after the shocks compress due to the tongue weight (see around the 11 minute mark of the video). I would guess your winch distributes the weight where as the tow hitch centers the weight on the frame behind the shocks.

We Explain Why Jeep Gladiator, Chevy Colorado ZR2 Frames Bent - YouTube

The winch weight and thrust is purely at the front ends of the frame rails. About the same place a receiver puts the load.
There's no weight distribution to a winch. If what you are pulling is close enough and down, the pull is downward and forward. How much is down depends on the distance from the truck and the angle.

There's more to it than that video - there's some perfect comments below it. Bottom line, almost all frame bends are due to the driver and the conditions, not a "defect" that's warrantable. Shock loading. The math is there. The frame is doing what it's supposed to do - crumple as if it's being struck from behind with a forward and downward shock.

I agree with the engineer that posted this bit - > A
pintle hitch does not necessarily offer more roll articulation than a ball hitch, and neither of these bent frames had anything to do with the hitch anyway. (and to that I would personally add - a conventional ball coupler would twist to far and then give and come off the ball. Unless you have a cast or forged coupler, that stamped steel of the coupler will only handle so much and then wedge off the ball or the tongue would twist)
..................
Too long a shock on the Gladiator could definitely play a part. If the shock is fully compressed BEFORE the axle hits the jounce stop, any further movement of the suspension is stopped 100% through the shock mounts, and tongue load at the hitch would rise very quickly as an impulse load into the frame. Now instead of the frame carrying the weight above the axle, while the section behind the axle is trying to bend down, the frame is carrying the load at the shock mounts well forward of the axle, and that same tongue load now has a longer lever in effect acting to bend the frame at the shock mounts. The longer the lever, the easier it is to bend something. (I'd personally want a tad bit more shock travel to go before the thing bottomed. I'd not want the shock to bottom first because it was too long)_
and - he says -
Finally, tire size has nothing to do with either of these. The tire size has no influence on how the frame, springs, and axle carry or handle weight like this. The tire "spring rate" from pressure really only matters once the vehicle has completely used up all available suspension travel, and even then it's really not likely to make much difference, whether at 50psi or 20psi. The whoop theory is right on.
I'd bet money that both drivers overcooked some sort of dip, and trailer weight became tongue weight, probably with a good application of tow vehicle brakes thrown in at the same time to amplify it. You simply can't put that much vertical force into the hitch of a light truck like these and expect that the frame won't give. That kind of loading is simply behind what is reasonable.


Yup - this guy who said he's an engineer said it well i his comments below the video.

In this case of this bent frame in this forum - there's simply too much unknown, things NOT being shown.
As far as body/box mounts - I don't see that as being the issue. It's a matter of math there as well....

Forgive my VERY crude drawing, but for the box to have settled enough to have that large a gap difference at the cab top to bottom, the rear of the box would have to be on the frame. The box front is a perfect 90 degrees from the bed so a person could take a carpenter's square or framing square and line it up and calculate how far down the box would have to be in the rear compared to the front which we might assume is normal height - and I bet it would put the box directly on the frame rails to be off that much.
I may be wrong - I'm guessing and trying to see it in my head and I've not taken my big squares and straight edges to my own truck to try to figure it - but it just seems unlikely it's box mounts.
BUT - that's sure easy enough to check - crawl under it!
Now - are only the CAB mounts hydraulic pads or are the box mounts also liquid filled?

 

[MyRight]

My gap is larger on the driver versus passenger. The rubber doesn't even touch. You can't see it unless you look for it. Everything looks straight from each side and from the rear. This seems like looking for a problem that isn't there.

Yep, I did the finger measurement to my JT today and there is certainly a larger gap on the driver's side than passenger side. I can fit my pinky finger between the cabin and the rubber at the top on the driver's side. The gap closes the towards the bottom. The rubber is uniformly touching on the passenger side.
I don't think I have a bent frame, more like not quite lined up bed.

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