Truck Camper COG

[CrowsnestGuy]

I have a 1995 Security 10C Timberline truck camper and cannot seem to find a listing for the COG on this unit. The company is out of business I believe, so how can I find this information? Thanks

[Reddog1]

I think if my TC CG is over the center of the axle, I can put at least 500 lbs over the rear bumper just based on the OEM numbers. As built, my truck has 500 lbs tongue weight stamped on the rear bumper. I bet it is limited more by the strength of the bumper than the truck.

My TC (11.5 ft) weight is 3800 lbs. My black tank and gray tanks are on the small side, but both are behind the rear bumper. I don't care if they are empty or full, my truck handles the same.

Wayne

[Kayteg1]

COG will be always important with longer campers.
On my 11-9 camper COG is behind rear axle with empty holding tanks. The 6300 lb add 6500 lb on rear axle, leaving not mach load reserve.
Meaning don't even think of driving with gray water farther than to the end of campground.
I mount Honda 3000 on front platform and it changes a lot, but doesn't look too good.

[adamis]

I find the center of gravity topic to be peculiar simply because manufacturers go out of their way to design the camper to have the ideal center of gravity but then all of the holding tanks are typically in the back of the camper. As an example, my fresh water tank sits at the very front of the camper and with 40 gallons weighs 333 lbs. However my holding tanks are pretty much over the tailgate meaning my center of gravity is going to vary widely just based off where my fluids are. I suspect most other campers are similar.

Back to your question at hand, is finding the COG of particular importance or are you just curious to know for knowledge's sake?

[Powerdude]

Rustofer is mostly correct.

That calculation assumes the truck stays level. If it doesn't, and the truck tilts backwards due to load (or forwards, quite unlikely), it will shift the weight and the COG more towards the rear axle.

Then you may have to do some trigonometry, but it will be largely irrelevant.

🙂

Either way, the weight will tell you where the COG is.

[jimh406]

Are you trying to avoid a problem or just curious? A 10 ft TC would be made for a 8ft bed. That's really all that you should need to know.

If it is about weight on rear axle, you'll have to go to a scale to know for sure.

[Rustofer]

Here's one idea to find your true camper COG from a weigh scale:

Weigh your truck, front and rear axle weights separately, without the camper.

Re-weigh with your camper, with the same truck conditions (passengers, fuel, etc) and get the loaded front and rear axle weights.

Your total weight difference is your camper weight (obviously).

Knowing your wheelbase and the difference in axle weights, you can calculate your exact COG.

The proportion of camper weight carried by your front axle will be equal to the proportion of distance between your rear axle and your camper COG. If your loaded front axle becomes lighter, your COG is behind your rear axle.

Here's an example:
Unloaded front axle 4500 lbs.
Unloaded rear axle 3000 lbs.
Loaded front axle 4700.
Loaded rear axle 6500.
Wheelbase 160"

Camper weight: 3700 lbs.
Proportion of camper weight on front axle = 200/3700 = 0.054 or 5.4%
5.4% of 160" = 8.6"
So your true COG lies 8.6" ahead of your rear axle.

Of course, that is true only for the way your camper is loaded. Changing the weight distribution in the camper (water, food, etc.) may change your actual COG.

Hopefully this makes sense. I've dashed it off pretty quickly, so if I've made an error, I hope someone will point it out.