Frame Stiffing to reduce Porpoising?

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.