weight distribution

[BigWorm]

30psi, mine was also done on a weighbridge, we actually did the front wheels on the way on & the rears on the way off, and I'm pretty sure it was 540/520kg. As brett said it doesn't have to be right over the B pillar as the weight on the front or back wheels wouldn't change.

both of you (worm and turbo) have your batteries in the boot don't you?

Yes mine had the battery in the boot at that stage. It also had tools, surge tank & fuel pump etc, jack, and maybe 1/4~1/2 a tank of fuel.

aircraft are weighed at major services where the weight and balance changes. the plane will have scales [strain gauges] under each wheel group. this way you get centre of gravity in 2D

They actually have scales under each wheel. Impressive seeing 18 seperate scales reading almost 20 tonnes each! But what's that got to do with RA23s F/R weight distribution?

[adamaw11]

Where do you actually find these weigh bridges? Does it cost anything to use? Do any of you guys just go to the dump without dumping any rubbish?

[kingmick]

not the best way to work it out! corner scales is the way to do it and even these have to be calibrated often. A weight bridge is in the ball park, but ball parks can be very big and hanging half a car off, is a good guess at best!

[kingmick]

Bit like an off centre seesaw

[brett_celicacoupe]

not the best way to work it out! corner scales is the way to do it and even these have to be calibrated often. A weight bridge is in the ball park, but ball parks can be very big and hanging half a car off, is a good guess at best!

doesnt really matter if there is a callibration error with the scales as you will still end up calculating the same ratio

ie a car with a 50 kg on the rear and 100kg on the front has the same weight dist. as a car with 100kg on the rear and 200kg onthe front.


as long as you weigh the front of the car, and then the rear youll be fine. as opposed to total weight and front or rear.

only 2 measurements are needed to calc the weight dist.

["Z" UTE]

adamaw11, public weigh bridges, can be found, at railwat depots, garbage tips, and landscape supply yards to name a few. Cost depends on who operates the weighbridge.

cheers Chuck.

[kingmick]

oh fucking really! is that how it works, so pivot angle will be worked out to the fucking mill will it! Fuck me dead, every one is wasting there money getting there race scales claibrated all the time. We could all just buy two scales.
hahahahahaahah. sorry im being harsh but fair. mate to do it properly you measure the car on its disc's then once it even you scale it,
What you talking about id like me taking a guess what the car weights!

[kingmick]

and i was quoting brett_celicacoupe post! lmao

[brett_celicacoupe]

if your arent trying to find the overall weight, just the weight distributution of the car then the accuracy of the scales doesnt matter. what does matter is the precision of the scales

example;

say a car has a known total weight of 1000kg. 600kg being on the front 2 wheels and 400kg being on the rear....

this would be a 60/40 weight split; front/rear


now you put the car on some dodgey scales which read 10% heavier then the actual value.

you find the front wheel weight to be 660kg. you find the rear weight to be 440kg.

so total weight is 660+440 = 1100kg

now the front distribution is [front weight]/[total weight]*100 = 660/1100 = 60 %
the rear..... [rear weight]/[total weight] * 100 = 440/1100 = 40%

= 60/40 weight split; front/rear



now you put it on another set of scales.... this one reads under by 12.39482%

you find the front wheel weight to be 525.63108kg. you find the rear weight to be 350.42072kg.

so total weight is 525.63108 + 350.42072 = 876.0518 kg

now the front distribution is [front weight]/[total weight]*100 = 525.63108 / 876.0518 = 60%
the rear..... [rear weight]/[total weight] * 100 = 350.42072/876.0518 = 40%

= 60/40 weight split; front/rear

this will work for nearly any callibration factor error

[30psi 4agte]

woooooooohoooooooooooo I love it when it gets spicy !!!!

[brett_celicacoupe]

kingmick; im not discrediting your race practices......im sure you actually want to know the actual weight (and other stuff) of the vehicle rather than just the front-rear weight dist.

you probly also want to check the weight distribution between left and right as well? in which case 2 scales will not suffice

[Hiro]

this will work for nearly any callibration factor error

Unless it's an offset callibration error and not a percentage one.....if the scales are out by 10 kg (ie say -10 when nothing is on them), then there will be a big differerence if the weight on the scales is close to the offset error.


ie 20 kg front, 12 kg rear would read 10kg front, 2 kg rear, which is a different ratio

[kingmick]

Even front to back, you will be lucky to even get close! unless you get the car dead centre of the C of G.lol cant see that happening often.

[brett_celicacoupe]

yes but i didnt mention that because all good scales have a 'zero button'

[LeeRoy]

Unless it's an offset callibration error and not a percentage one.....if the scales are out by 10 kg (ie say -10 when nothing is on them), then there will be a big differerence if the weight on the scales is close to the offset error.


ie 20 kg front, 12 kg rear would read 10kg front, 2 kg rear, which is a different ratio

But you could look at the empty scales and get a reading to take off the reading you get when the car is on there.

Could you also measure the sag on springs in the car. ie jack car up and measure spring height, then with the springs stiffness, measure the sag on each corner when you jack it down and work out the weight on each corner?

- LeeRoy