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mkirsch
Rochester, NY
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Joined: 04/09/2004
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To paraphrase, "If you find somebody willing to weld on your frame... you don't want them."
Why not? Thousands of commercial truck frames are welded on a daily basis. They cut 'em behind the cab and splice in a piece to add length. They install frame liners to add strength.
Older pickup trucks are routinely shortened to convert them into the more desirable "short box" versions.
Stock frames are boxed in all the time for offroad applications.
Putting 10-ply tires on half ton trucks since aught-four.
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Grit dog
Black Diamond, WA
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Meh, the funny math doesn’t really prove anything.
Especially since you’re speculating about 2 out of the 3 weight factors. People and stuff and actual camper weight.
$20 says your 7600lb truck, camper and everything in/on the truck is right around 13klbs.
Maybe 12,500.
I’m not saying I wouldn’t haul it. Quite the opposite in fact, but you’re arguing with yourself again, now trying to prove how light it is I guess? after starting the thread about how heavy it is!
Sometimes these things require one to do a little easy real world information gathering. Like weigh the whole thing and don’t be forgetting anything.
Although what it actually weighs is largely immaterial except to settle the speculation.
And measure the deflection if it’s worrisome (which you also said it’s not, but a definite annoyance). Easiest idea I can think is tape/attach a crude dial indicator to a vertical surface between the camper and the back of the cab at the top of the cab. Like a tire depth gauge maybe. Long enough to touch both surfaces.
See how much it compresses over some bumps at low and high speed.
From that you can do some trig and figure the max rotational angle the frame is flexing and the total amount of droop/flex.
But that is also really just a science experiment…. But better than speculation since it’s bothersome or perplexing.
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adamis
Northern California
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mkirsch wrote:To paraphrase, "If you find somebody willing to weld on your frame... you don't want them."
Why not? Thousands of commercial truck frames are welded on a daily basis. They cut 'em behind the cab and splice in a piece to add length. They install frame liners to add strength.
Older pickup trucks are routinely shortened to convert them into the more desirable "short box" versions.
Stock frames are boxed in all the time for offroad applications.
Thanks for the comment. This was along the lines of what I was thinking when I asked the question. I know it isn't common and you don't want just any shop doing it but clearly there are places that do it for the reasons you mentioned.
1999 F350 Dually with 7.3 Diesel
2000 Bigfoot 10.6 Camper
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valhalla360
No paticular place.
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time2roll wrote:I am curious if the weight rating is primarily given for a load low in the bed with less front to rear rotational mass. I mean to say a load 4000# of gravel vs 4000# gooseneck vs 4000# truck camper are very different on the dynamic frame stress even if the static downward pressure is the same.
Most certainly it does. That's why they provide a separate LOWER payload for truck camper use.
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HMS Beagle
Napa, California
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Joined: 08/22/2003
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mbloof wrote:TxGearhead wrote:
OP: are you sure you're not just seeing the camper rock back and forth, the spring loaded Fastguns doing their job?
I always get a kick out of these sorts of comments. ![[emoticon]](http://www.rv.net/sharedcontent/cfb/images/smile.gif "smile")
So a flat hard object sitting flat on another flat hard object is "rocking"??!?!??! hahahahahahahaha
.
Clearly you have little knowledge of material science. "Hard" and "flat" are relative terms. Steel is quite flexible, fiberglass very flexible, and any rubber map between them extremely flexible. Neither the bottom of the camper, nor the bed are flat, nor do they stay flat running down the road.
Bigfoot 10.4E, 2015 F350 6.7L DRW 2WD, Autoflex Ultra Air Ride rear suspension, Hellwig Bigwig sway bars front and rear
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Grit dog
Black Diamond, WA
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^Uhh, yeah they are both “flat” for the purposes being discussed here.
Save for some o them newer trucks with an actual crown in the bed.
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mbloof
Beaverton, OR
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HMS Beagle wrote:mbloof wrote:TxGearhead wrote:
OP: are you sure you're not just seeing the camper rock back and forth, the spring loaded Fastguns doing their job?
I always get a kick out of these sorts of comments.
So a flat hard object sitting flat on another flat hard object is "rocking"??!?!??! hahahahahahahaha
.
Clearly you have little knowledge of material science. "Hard" and "flat" are relative terms. Steel is quite flexible, fiberglass very flexible, and any rubber map between them extremely flexible. Neither the bottom of the camper, nor the bed are flat, nor do they stay flat running down the road.
Granted nothing is hard/flat like a rock or chunk of concrete and almost everything has 'flex'.
The $64 question is how much? So flat camper sitting on flat bed on top of flat side of frame rails.
Is the camper compressing/expanding? Not likely.
Is the bed compressing/expanding? Again no. However given the support is in the center of it surely if enough force were applied to ether far side or single corner it might 'twist' or 'rock' side to side.
Is the camper 'rocking in the bed'? Again no. (unless it is on a thick soft rubber mat (horse stall mat comes to mind here)
Is the bed moving around on the mounts to the frame? Maybe, many have rubber mounts (to account for frame flex/twisting, see the side2side above).
Is the frame flexing/twisting? Sure, they are known to do that.
IMHO: Given the pivot point is the center of the frame and the camper nose is ~6-8' forward of that what the OP is seeing is minor frame flex amplified by the distance between pivot point and tip.
- Mark0.
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JIMNLIN
Oklahoma
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Joined: 09/14/2003
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Quote:Is the bed moving around on the mounts to the frame? Maybe, many have rubber mounts (to account for frame flex/twisting, see the side2side above).
I've had 8' and 9' 6" and 10' 6" truck campers on several different GM and Ford one ton drw service trucks. All three TCs were held in the bed with stake pocket tie downs or TC bolted thru TC floor to the bed frame.
At speed the TC tied solid to the bed had lots of lateral and vertical movement. I used truck camper shocks (camper to the cab mounts) to control the harsh vertical movement on rough roads. I've watched the shock extend a good 2" to 2 1/2" going into a strong head wind at highway speeds...so yeah lots of bed movement in this scenario.
Granted all my LDTs in service were not the long WB crew cabs which don't work the best pulling heavy GN flatdecks in and out of close shipping yards/worksites/etc but IMO there probably would be more TC/bed/frame movement with the longer wheel base.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
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Grit dog
Black Diamond, WA
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Or to sum up 8 pages, it’s a big camper on a pickup truck. One that arguably flexes more than new trucks and it’s ok.
If you wanna find a shop to disassemble frame cross braces, probably pull the trans, move/re-rout brake lines, fuel lines, electrical, drop the tank etc and then try to fit/cab it all up to fit back in there like it was after doing idk what to the frame, have at it. It’s a bad idea on all fronts.
That’s all. Easy peasy…..
On a similar note I had a new 89 Dodge 1 ton truck at work that the guys would constantly overload so bad it would sit hard on the bump stops. (Not my truck and wasn’t the boss, just a high school kid turning wrenches.).
They broke the frame on one side right over the axle. We paid a shop to repair it. (In 1990).
Then the other side broke the same way. I copied the first repair. And the truck frame was still in one piece years later. But that was FAR easier than what is being proposed here….
And it was a work truck that got the tar beat out of it daily. Whole diffenrrt scenario
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HMS Beagle
Napa, California
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Joined: 08/22/2003
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mbloof wrote:HMS Beagle wrote:mbloof wrote:TxGearhead wrote:
OP: are you sure you're not just seeing the camper rock back and forth, the spring loaded Fastguns doing their job?
I always get a kick out of these sorts of comments.
So a flat hard object sitting flat on another flat hard object is "rocking"??!?!??! hahahahahahahaha
.
Clearly you have little knowledge of material science. "Hard" and "flat" are relative terms. Steel is quite flexible, fiberglass very flexible, and any rubber map between them extremely flexible. Neither the bottom of the camper, nor the bed are flat, nor do they stay flat running down the road.
Granted nothing is hard/flat like a rock or chunk of concrete and almost everything has 'flex'.
The $64 question is how much? So flat camper sitting on flat bed on top of flat side of frame rails.
Is the camper compressing/expanding? Not likely.
Is the bed compressing/expanding? Again no. However given the support is in the center of it surely if enough force were applied to ether far side or single corner it might 'twist' or 'rock' side to side.
Is the camper 'rocking in the bed'? Again no. (unless it is on a thick soft rubber mat (horse stall mat comes to mind here)
Is the bed moving around on the mounts to the frame? Maybe, many have rubber mounts (to account for frame flex/twisting, see the side2side above).
Is the frame flexing/twisting? Sure, they are known to do that.
IMHO: Given the pivot point is the center of the frame and the camper nose is ~6-8' forward of that what the OP is seeing is minor frame flex amplified by the distance between pivot point and tip.
- Mark0.
Does the camper flex? Absolutely. A Bigfoot probably more than some other brands due to the construction method. You can sit one on rigid supports or concrete, and get the nose bouncing a bit just with your hands. Does the bed flex? Again, absolutely. I carry machine tools in the bed, about the same weight at a camper, CG much lower, the tools themselves are VERY rigid being cast iron and designed specifically for rigidity, yet you will see them visibly rocking forward and backward as you drive. That will be true even when placed on 6x6 sleepers directly over the frame. The bed is after all just thin sheet metal, supported by sheet metal hats of low section. On an F350, no rubber, bolted directly to the frame. The cab supports have rubber.
I'd agree the question is, how much? It is easy enough to test, just tape a piece of wire onto the overhang so that it comes close to the windshield or mirror or some other point of reference, mark that with some tape. Movement is pretty easy to see, how much is difficult to estimate without a close reference.
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