There use to be a calculator somewhere for this. What is the formula for calculating wheel weights with given Left, Rear and Cross percentages for a given total weight?
Total Weight = 2390
Cross % = 49.2
Left % = 53.1
Rear% = 55.2
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There use to be a calculator somewhere for this. What is the formula for calculating wheel weights with given Left, Rear and Cross percentages for a given total weight?
Total Weight = 2390
Cross % = 49.2
Left % = 53.1
Rear% = 55.2
Back to algebra class!!! That's all it is my friendQuote:
Originally Posted by collateralDamage
Example: LF= Left side(.531) X front weight(.448) X total weight(2390) = 569
Algebra class was 30+ years ago my friend. Is it a a secret?Quote:
Originally Posted by 7uptruckracer
Quote:
Originally Posted by a25rjr
Thank you!!
Sorry wasn't trying to be rude but that's how I did it. I wrote it out to show you just was trying to figure out how to scan it to show you my work (like math class back in the day. )
Quote:
Originally Posted by collateralDamage
From an algebra standpoint. You've got 4 independent variables. Knowing the totals for all of them (the total weight of the car) and 3 totals or any 2 (left total, rear total, and cross total), you can solve for one variable and then solve for all others based on that.
I made a spreadsheet that does it. I'm afraid to attempt to attach a file on here but I can share the methodology and you can make your own or just do it on paper for that matter.
Write down your desired total weights, left side percentage, rear percentage, and cross percentage.
For example, 2350 total, 54% left side, 53% rear, and 50% cross.
Now calculate the left total, rear total, and cross total.
In our example left total is 2350*.54=1269
Rear total is 2350*.53=1245.5
Cross total is 2350*.50=1175
Now we take the sum of all of these numbers (3689.5) and subtract the total weight of the car (2350) and we end up with a number of 1339.5. We divide that number by 2 and this give us our LR wheel weight of 669.75 pounds.
Don't ask me to prove my work. I've done it and trust me, this works. I'm just simplifying the several other formulas it takes to arrive at the LR number. Once you have solved for the LR, the rest is easy.
The LF is the total left side number (1269) minus the LR (670; rounding to the nearest pound) which equals 599. So 599 is your LF wheel weight
The RF is total cross weight (1175) minus the LR (670), which is 505 for the RF.
The RR is the total rear weight (1245.5) minus the LR (670), which is 576 (rounding again) for the RR
So we have the following wheel weights:
LF 599 RF 505
LR 670 RR 576
If you calculate the percentages from these wheel weights using the formulas we all know, you'll see that we've nailed our desired numbers, which proves that the “reverse” formulas worked.
http://www.4m.net/showthread.php?356...hlight=Scaling
Worked on this last winter. This app works.
Okay, you are essentially solving a system of four equations with four variables. Based on what we have to work with, the solution will certainly be unique.
Let a=LF
Let b=RF
Let c=LR
Let d=RR.
We want a+b+c+d=2390
a+c=.531(2390)
c+d=.552(2390)
b+c=.492(2390)
Now, we could go nuts with normal algebra, but it's a pain. We can use something called a matrix, used in Linear Algebra, to solve this system. You can then use a free computer algebra system like Wolfram Alpha to solve this using matrix operations. If you go to wolframalpha.com and enter "rref{{1,0,1,0,1269.09},{0,0,1,1,1319.28},{0,1,1,0 ,1175.88},{1,1,1,1,2390}}", without the quotes, you will see the answer to your problem...with a=581.965, b=488.755, c=687.125, d=632.155.
Hope that helps
http://www.thedirtforum.com/reversescaling.htm
Here is a short cut if you don't want to do the math, lol.
Thedirtforum that killed itself with "upgrades" sighQuote:
Originally Posted by billetbirdcage
I was flunked out of algebra class after I refused to join the HS football team... and science, too. Tuff to pass when you turn down the two teachers who run the football program...
Not sure if you still need this or not. I have a calculator on my simulation page that will do this. Go to "SIM LOG IN" and create an account (it's free). Once logged in, go to "Virtual Scales". It should do the trick for you.
Joe
http://www.bartlettmotorsportenginee...imulation.html