Center of Gravity | Ford Explorer Forums - Serious Explorations

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Center of Gravity

rookieshooter

Moderator Emeritus
Joined
March 13, 2005
Messages
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City, State
Martinsburg WV
Year, Model & Trim Level
84 BII "Li'l Samson"
Below is a responce I posted on another site. Thought it might be of interest.


Looks good. I would only have your lightist items in that roof rack. Other trucks can get away with it, but not the allready top heavy B11s. The heaviest stuff should be low as you can get them. I would not even think of putting a High Lift jack up there let alone a tire. With all that weight up there your COG really got a lot higher.

Your center of gravity is a spot in your truck that you can not see. Now lets say that you can see this spot. Lets say that this spot that you can now see looks like a tennis ball that's between your two front seats about elbow high. Now lets put a string with a weight at one end and the other end attached to the ball. The weight end is just off the surface of the road. The truck is level. Now imagine that your outside and your B11 is looking away from you. You can see this magic ball and string hanging down. LOL. Now the B11 starts to lean over to the left. The ball stays at the same place, but the string with the weight now acts like a pendelum. The further your truck leans to the left, the further the pendelum swings to the left. Gravity is pulling it straight down so the string is allways straight down but the truck is leaning. As long as the end of the string stays within the outside edge of the tire, it will stay upright. The further the truck leans the more that string wants to swing to left. Actually the string stays in the same plane. The truck is moving not the string. Once the truck leans far enough and the end of the string is now on the outside of tire. Bingo roll over. Now this is a picture book example, but that is how it works.
Now here is what I'm getting at about all that weight you have so high. This dramaticaly raises that imaginary COG tennis ball. Now picture that COG up around you shoulders and not at your ellbows anymore. It will take less leaning of your truck for that weighted string to be outside your tire. The higher that spot the more it swings out side the tires and the less the truck has to lean. Picture it this way, the majority of the weight is on the right side of the string as long as the weighted end is on the inside of tire. Once the string is on the outside edge of tire the majority of weight is on the left side of string and the truck has to roll. With ramps and scales your can figure your COG. Hope I did not bore you
 






When I worked for a large truck manufacturer (starts with "P") they actually had a large tilt table (at the Technical Center) so they could determine the COG on individual trucks. It was kinda cool, but not practical for the home mechanic. ;)
 






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