# Center of gravity/ weight distribution

1. Feb 24, 2009

### AE72twincam

Honestly I know I'm right as far as what I said in a conversation regarding the effects to the mechanical components we were discussing. Basically all I'm looking for is someone to look at how I explained the physics and if there is a better way to explain this to them because its not sinking in. Here is a link to the thread it all started on page two post 18 because I said road crowns will cause a weight distribution that will wear out the pass side springs faster then the drivers side. Anyway link to thread any input is greatly appreciated.

2. Feb 25, 2009

### DaleSwanson

So after reading through that thread the questions seems to be: A 1200kg car on a 2% grade from left to right, with a width of 1.7m, and an extra 80kg in the left side. What is the weight distribution at the wheels?

The 2% grade would cause the one side to sit 3.4 cm higher than the other. This should cause the weight distribution to be 50.64% / 49.36%. For our 1200kg example that means 607.64kg and 592.36kg. That's an extra 15.28kg. That assumes perfect weight distribution to begin with though, and number of things could give a car 15 extra kg on one side. I'm not sure how to do the weight of the driver, but I'm pretty sure most of his weight would be on the other side, and the difference would be more than 15.28kg.

Then as for the amount of time a car spends on the road, this is a lot harder to estimate, and will vary hugely from driver to driver. Assume 12,000 miles per year, average speed of 35mph, gives 343 driving hours, out of 8,760 hours in a year, means about 4% of a car's life is spent on the road. Again this part is really just a guess.

If you have access to a heavy scale you could test this by just weighing one half of the car at a time.

3. Feb 25, 2009

### AE72twincam

That is a vary good post thank you.

Now as for weight distribution at the wheels the car we are discussing has a 50/50 front to rear ratio and I'm not 100% sure on the side to side ratio but on the left hand drive version in question the car will be more weight bias towards the pass. side (because of gas tank and mechanical component placement).

Another thing that plays a role in spring life is metal fatigue. When you are driving down a crowned road and cross an opposing crowned road the tire at the top of the current crown will travel less then the tire sitting lower on the crown while crossing over the opposing crowned road. We all know every time you stretch compress a piece of metal it gets weaker and because the drivers side will always be at the top of the crown the pass. side spring will see much more compression and decompression throughout its 250,000 mile life.

I greatly appreciate your detailed response but I know I am right as far the effects to the mechanical components go all I'm looking for is another way to explain the physics involved in weight transfer of a set ratio object so that maybe these people might understand. Again thank you for your response and thank you to anyone else who takes the time to respond to this.