Does anyone know or have a formula for calculating spring rates on forza 5? Any help would be great thanks
do a search for 3 minute tune.
this is a starting point.
I found it for you
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You don’t need to calculate anything on a car… It won’t take you more than a few minutes to play around with the spring rates and figure out what feels right to you.
Spring rates have huge impact on the ride/handling quality therefore it should be one of the first parameters to nail down.
You have to do 2 things: 1. Set the overall rate, then 2. Balance front & rear.
The default spring rates are almost always too stiff. So starting from the default values
- If the car is sliding around a lot, locking up brakes easily, and powered wheels losing grip easily, then reduce front & rear by 100 lb/in.
- Continue to reduce by 100 lb/in at a time until the car feels too slow to respond, awkward, and/or generally plush. Then INCREASE front & rear by 50 lb/in.
- This is your overall/basic rate - for your driving style
Then balance it by:
- If understeering, reduce the front by 20 lb/in at a time
- If oversteering, reduce the rear by 20 lb/in at a time
Once you are satisfied with it, then proceed to ARB, Dampers, and Differential settings, in that order.
Springs: supports the car in general, acceleration/braking performance, ride over curbs, hills & valleys
ARB: works in conjunction with springs to provide additional cornering support (so only works in corners)
Dampers: controls how the car absorbs braking & acceleration + corner entry/exit
Differentials: controls how the torque is delivered to the powered wheels (left and right balance) during braking and in acceleration.
Good luck.
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This is by far one of the best descriptions of how to set up springs I have read on the forums. Thank you grd.
Thanks ppl, I was after a base setting to make my tune from for the bmw m3 gt2. I’ve just had a thrustmaster wheel and can feel all the problems with my current tune. I’ll give everything a go and see what happens
Here is a link for you that you might like! It’s free and it’s still somewhat applicable to Forza 5…
http://www.forzatraders.com/flash/ForzaMotorsport3CarSetupTool.swf
If you want a Spring equation here is one 
Spring=[(2π)²÷t²]*M
M=Mass
t=1.25s constant or 1.50s or 1.75 the higher t is the slower the bounce=more difficult to handle too sluggish… 1.25 is BEST….some cars can handle 1.75. For cars at and below R class ALWAYS stick with 1.25
Weight% is in decimals!
Front M=[(Weight÷Front Weight %) 0.5]÷32
Rear M=[(Weight(100-Front weight %)]÷64
WHY 32? Why 64?
Here is why….
The acceleration that an object experiences because of gravity when it falls freely close to the surface of a massive body, such as a planet. Also known as the acceleration of free fall, its value can be calculated from the formula
g = GM / (R + h) 2
where M is the mass of the gravitating body (such as the Earth), R is the radius of the body, h is the height above the surface, and G is the gravitational constant (= 6.6742 × 10-11 N•m2/kg2). If the falling object is at, or very nearly at, the surface of the gravitating body, then the above equation reduces to
g = GM / R 2
In the case of the Earth, g comes out to be approximately 9.8 m/s2 (32 ft/s2), though the exact value depends on location because of two main factors: the Earth’s rotation and the Earth’s equatorial bulge.
32 feet per second=Gravity
I hope this helps
Psycho Sasuke,
I think the formula for Rear should be:
[(Weight*(1-Front weight %)]÷64
Since Weight% is in decimal and you are trying to convert it to Rear Weight%.
Thanks to you this is the formula I derived:
Front Spring = ( ( ( 2 * PI() ) ^ 2 ) / ( 1.25 ^ 2 ) ) * ( ( ( Car_Weight * Car_WeightDistribution_Front ) * 0.5 ) / 32 )
Rear Spring = ( ( ( 2 * PI() ) ^ 2 ) / ( 1.25 ^ 2 ) ) * ( ( Car_Weight * ( 1 - Car_WeightDistribution_Front) ) / 64 )
Thanks!
Sasuke,
How do you take the suspension geometry into account? Would this work for both passenger cars and open wheel cars which have vastly different suspension geometry?
Hi GRD 4 3L ! First let me say that I love your method and it’s Error proof and it’s the MOST FUN WAY TO TUNE! Also The Bulin Wall5 is right you don’t need anything. All you need is a good feel and understanding for the car. But Bill 0ddy asked for an equation. That’s the only reason I gave him one. This is just PLAIN NERDY and NOT for everyone! .And to answer your question yes it would work for both (you can change t for quicker/slower spring movement). Also for the record it’s not my equation(much smarter people came up with it) But I have been testing it for the past few months and in MY OPINION it’s a VERY good equation and the math is accurate, and it’s based on real physics…You have to try it compare it to your own numbers. See how it feels test it on the track and make your own opinion (That’s what I did when I saw it)
Good luck…
I’ve used this equation and (for some reason!) has worked for FM5. However, one word of CAUTION…if you look at the units, it still needs to be divided by 12 in order to get the units to by LBS/IN (spring). So, I think it’s an issue of the starting frequency that this equation assumes to analyze the spring itself. So, may need different values for “t” in order to get the correct units.
Use the equation as is! And best value for t= 1.25 If used correctly the final result for front and rear spring rate is in LBS Also another thing to add is that this equation will give a NEUTRAL suspensions setting. What is NEUTRAL? Neutral suspensions balance has no over-steer nor under-steer it’s NEUTRAL and better than FORZA stock numbers
Good luck everyone
Yeah, that is what I have done in the past.
However, please check the dimensions and you will see they end up being lb/ft, thus, need to convert to lb/in…hence the value of 12 in/ft not considered. If this is the same coming from Mike at GC&D’s, then, he actually admits to this error. Check his YouTube video.
Look within the comments area…
If the weight distribution is 50/50 I usually start with 25% of the cars weight on the front springs and about 22% on rear. I then test from there and often end up with lower figures, particularly on the rear.
I adjust if the weight distribution is different but I don’t get too scientific as the final figures are set in testing.
I agree.I don’t pay too much attention to the scientific final figure either. But it’s good to know where the neutral balance is. I’m only comparing this to the stock values that Forza gives you as a starting point for tuning. And lets be honest Forza numbers are very random.You can use their numbers as starting point or you can use other numbers. The final figure should ALWAYS be determined by feel!
Test drive, if it oversteers then adjust, if it understeers then adjust. Mess with the settings to see what it does what and how the car reacts.
Wow,very nerdy posts lol. Using a formula is great if thats your thing,but i personally dont trust any method other than driving and testing. In my experience different tracks and cars benefit from different springs and tuning methods. For example,yes you can set your over/understeer to a point using springs,but roll bars,alignment,rebound also have massive impact on the feel of the car. Its a balancing act between all these settings. I often end up setting what feels best and produces the best laps for me early in the tune,but end up retweeking it further when i have the rest of the tune finalised. Alot of good info in this post from various people,but i expect these formulas are going to confuse some people,me included. 
+1
My best example… tweak, and tweak, an keep tweaking is the BMW M1.
After reading through this and doing a little math, I found the equation simplifies a lot. Here is what I ended up with.
Front spring = K * Weight * FrontWeightDistribution
Rear spring = K * Weight - FrontSpring
Where K is one of the following
For t = 1.25, K = (pi^2) / 25 = 0.394784
For t = 1.50, K = (pi^2) / 36 = 0.274156
For t = 1.75, K = (pi^2) / 49 = 0.201420
For a car weighing 2500 lbs. with a weight distribution of 60% front and 40% rear and using t = 1.25, I get the following values
Front spring = 592.2
Rear spring = 394.8
This seems a little low to me. Can someone verify that they get the same numbers?
That is low but some people use very soft springs.
My calcs for that would be total weight x front /2 = 2500 x .6 / 2 = 750 front
Rear = 2500 x .4 / 2 and reduced a little more lol = 450 ish.
I would start with those figures in testing and go from there with softening being the usual direction during testing.