New to TCs and researching my first purchase. I've recently read about COG and I have seen it measured in numbers such as .54 etc. does the mean the center of gravity is 4" in front of the rear axle?Also some camper floors are at bed rail height others are at the wheel well height and smaller units the TC floor sits on the truck bed. I understand the higher floor from the truck bed the more storage but what are the downsides to a TC with the floor above the bed rails?Thanks folks, I'm taking advantage of your knowledge in my TC research.

To make it confusing different brands measure COG differently. Most measure from the front of the camper back. Lance for one measures from the back of the truck bed forward. Most pick-ups have a CA (cab to axle) legth of 54 inches. Cab and chassis trucks have a 60 inch CA. So, a camper with a COG of 54 or less if measured from the front will have the COG right over the rear axle.Raising the floor gets you more floor space but a taller more top heavy camper. It also increases the ceiling height in the bed area and reduces the step height to get in the bed.

Actually, I believe Lance's recent brochures state "Center of Gravity is measured from the front of the truck bed towards the back."

The TC world refers to the front to rear balance point of the TC as the Center of gravity (CG).The higher the floor level, typically the more top heavy the TC. The higher the floor level, typically the greater the winds effect on the TC, especially side winds. From what I have observed, a North to South bed typically requires a raised floor. Typically, an East to West bed is a non-basement. To my knowledge, TCs with slides must have a basement to allow the slide to go out. Usually puts the floor at bed rail height, some may be at wheel well height. To accommodate larger water tanks, holding tanks, and/or a North/South bed, a basement is usually required. I believe approximately wheel well height is the most common. Although it is true smaller units the TC floor sits on the truck bed, it is also true of larger TCs, especially older large TCs. To my knowledge, none have slides, and usually have smaller water and holding tanks than basement TCs. My TC is a 11.5 foot TC, definitely not small. It is a non-basement TC, and sits flat on the floor. It is carried on my 2WD truck, and from ground to highest point is 10'3". On the same truck, a basement model would be at least 12-inches to 24-inches taller.The downsides to a TC with the floor above the bed rails depend on your camping style and preferences. In my opinion, the taller the TC the greater the need for a dually, for stability. Not a must, but more stable. The higher the TC,the greater the wind will affect driveability, especially side winds. The higher the floor from the ground, the taller the step required to get in the TC. The taller the TC, the more attentive you must be to avoid Tree limbs. In my opinion, the basement TCs are more vulnerable to water line and tank freezing than non-basement TCs.Wayne

Just a point of order here. TC's with a basement typically have a dedicated heating duct to the basement, this for cold weather camping. Also its a good idea to make sure that the dump valves are contained within the heated basement and not outside the heated area. My basement duct was a very restrictive accordion 2" which (per remote thermometer measurements) did almost nothing to prevent freezing. I kept it in place but ran a separate new 4" duct with a shutoff valve...after taking temp measurements the basement now stays within 5-10deg of interior temps...

COG Questions | Good Sam Community

JumboJet
Explorer
Jul 09, 2014
I will let the following picture speak for itself (Don't know if this helps)

:

Document can be found at:

RAM Body Builder Guide
sleepy
Explorer
Jul 09, 2014
Wayne... excellent post... and the earlier one was spot on too!

btw... all I ever added was airbags. (untill the 11th year when I added a couple of leaf springs)

You did it again... you and Jim gave me 90% of what I think I know but still have to ask one more time.

BTW... if anyone thinks I'm Sucking up to wayne you are correct... but I'll have you know that I sucked up to him for years before he was a mod.

He knows far more than he shares.
sleepy
Explorer
Jul 09, 2014
You are going to love this... I have all of the doc's and will post them later

We are all sort of correct... the manufacturers changed their methods... Lance between my order and recieving the camper

They had to furnish a consumer information document to new buyers (for insurance, lic plates, registratiom, loans, etc)

I special ordered our lance 1161 in 2002... it was delivered in Nov of 2002. (N150817 and registered as a 2003

The 2002 published COG was 43" in the buyers guide

I actually recieved a 2003 model.

the published COG for 2003 was 52" in the 2003 buyers guide

In the specific document for my individual 1161 the center of gravity is given two ways

55" from the front of the campers bulk head

and

41" from the point that contacts the rear end of the bed

On this camper the recommended center of gravity is in front of the rear axel... by about 6" or so.

the camper is 11'11"... 19'11" overall.

the weight dry was 3495 pounds
Reddog1
Explorer II
Jul 09, 2014
Maybe being a vintage guy and going to one of the old schools my COG (TC definition) is pretty simple to figure out.

With no TC loaded, at the wheel center (approximate) measure from the fender wheel well opening to the ground at all four wheels. Load the TC, and measure again. Compare the measurements.

1 If the loaded front measurement is less than the non-TC measurement. This indicates the COG is in front of the rear axle. This is preferred.

2 If the loaded front measurement is the same as the the non-TC measurement, the COG is directly above the rear axle. This may not be the best for steering comfort, but it is okay.

3 If the loaded front measurement is greater than the the non-TC measurement, the COG is behind the rear axle. This is not good. Depending on how far behind the rear axle the COG is, it can result in bad steering manors.

Weight distribution not only affects the handling charistics of the truck, but also headlight adjustment. With each of the above conditions, the rear axle will be carrying most of the weight. Due to this fact, the rear of the truck will squat more than the front. Just how much will be determined by your rear springs and how much the COG is in front of the rear axle. Consider this. Your headlights are adjusted without a load, therefor when the rear squats the headlights will be out of adjustment. Typically, they will be aimed higher than they should be. Will it be too much? Overload springs will not prevent this, but should reduce the amount of drop in the rear. Only something that is adjustable to bring the rear height back for correct headlight adjustment, airbags. The TC design and how it is loaded may put much more weight on one side of the truck than the other, with the result being a side to side tilt of the truck. This can also be corrected with the airbags.

Wayne
3_tons
Explorer III
Jul 08, 2014
jimh425 wrote:
Realistically, the COG is only important for short bed trucks. There aren't long campers made for both short and long bed trucks, but there are short campers made for both short and long bed trucks or only long bed trucks.

COG could also be used to compare two models, but I don't think many people choose only based on COG if they have a long bed truck. I could be wrong.

I also agree that the F450 is probably fine in any case.

This, A Logical summary!
jimh406
Explorer III
Jul 08, 2014
Realistically, the COG is only important for short bed trucks. There aren't long campers made for both short and long bed trucks, but there are short campers made for both short and long bed trucks or only long bed trucks.

COG could also be used to compare two models, but I don't think many people choose only based on COG if they have a long bed truck. I could be wrong.

I also agree that the F450 is probably fine in any case.
sleepy
Explorer
Jul 08, 2014
I was not trying to prove anyone wrong

Or to give my blessing to any TC/Truck combination

We have to start somewhere...

When you start "If" this is added it'll do "this"

If so, Then we'd have to start weighing the gallon of milk, the 3 cases of beer, the koolaid powder for the kids (they don't know any better)... then where

The camper is what it is with an established "factory new" COG that is referenced to decide what vehicle should haul it the very best.

Your tires have recommended air pressures... measured with cold tires... very few attemp to guess what pressures hot tires have...

So... if we stick with the factories designated COG we sould have all of the info we need to make good decisions... and not compound mistakes by attempting to effect a variance and get it wrong.
HMS_Beagle
Explorer
Jul 08, 2014
Here is an anecdote about COG: I carried for years a Bigfoot 9.6 camper that weighed a measured 2800 lbs (says 2200 on the sticker). I went to pick up my new camper, a Bigfoot 10.4 (2900 on the sticker but later weighed at 3500) and immediately on leaving the driveway noted that it drove better. It felt heavier in acceleration and braking, but the truck handling was noticeably better otherwise. Doing some careful weighing of both subsequently, I determined that the COG of the 10.4 is about 3-4 inches ahead of the 9.6. This may be do to the forward location of all the water tanks, propane, and batteries. Also bathroom and fridge are forward of axle. Both are basement models, but the floor of the 10.4 is about 3" higher than the 9.6. In any case the change in COG more than compensated for an extra 700 lbs, in terms of truck handling.
3_tons
Explorer III
Jul 08, 2014
A couple of things to consider:

Fact is, the advertised COG of a TC is measured with tanks empty. Unless the tanks are dead centered at that COG point (often unlikely) the addition of a substantial quantity of water will cause the COG to shift either forward or rearward depending on tank location.

As to the OP's rather substantial F-450, I doubt that he'll have much of a problem.

3 tons
mkirsch
Nomad II
Jul 08, 2014
Short bed camper on a long bed truck might put the COG 8-10" behind the truck's rear axle. Not a big deal. No worse than a 500lb tongue weight on the rear receiver.

Long bed camper on a short bed truck, now you're looking at a couple feet behind the rear axle as sleepy says. OK, if the camper is light, within the weight rating listed on the truck's glove box. Not OK if it's an 11' behemoth. Can you say WHEELIE!