Been recently looking for a quick way to determine a basic spring rate for tuning. Came across a number of older discussions and guides which basically suggested - with some variation - taking the weight over the front or rear (as determined by the weight and Front%) and dividing in half. However, so far this has been giving me results that look high (in some cases a bit beyond the maximum setting). Is there a better simple calculation?
Iām at work and itās been a minute since I thought about it, but if Iām thinking right (Iām not awake at all yet) itās the weight times the % halvedā¦ I think. So a 2400lb car at 49% would be 588lbs front and 612 rear.
I jad my own way of doing it before FM6, then I watch a few guides by J Runner or something like that. He broke down the actual math that he figured was used to give a default or good balanced tune. Iāve got his formulas written down but the values for things are different in these last couple games. Iām not a mathetist or scientition so I can be sure I converted things right. Iāll look for it when I get back home or check out his FM6 tuning YouTube.
Using imperial units, multiply weight * dist * value from below, ex. 2133lbs, 52% - 1066lbs over the front axle, 2133 * 0.52 * 0.2=221.8 front spring. Multiply by 1-dist (1-0.52=0.48) for rear springs.
0.99hz - 0.05
1.21hz - 0.10 - Very Soft
1.40hz - 0.15
1.98hz - 0.20 - Soft
2.21hz - 0.25
2.42hz - 0.30 - Moderate
2.62hz - 0.35
2.80hz - 0.40 - Stiff
3.13hz - 0.50
3.43hz - 0.60 - Heavy aero/limited travel
3.70hz - 0.70
3.96hz - 0.80 - Heavy aero+limited travel
To balance the springs perfectly, sweep the rear spring +/- 0.5lb per 25 (ex. with 520 front 480 rear spring, try between 475 and 485 rear).
Still in imperial units, for a specific frequency as a measure of relative stiffness, where mass represents the weight over the axle and K is spring rate in lb, use K=(HzĀ²M)/19.56. To find the rates of an existing tune use Hz=(K/M*19.56)Ā².
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Interesting. Do you have some example setups?
I build this calculator for this exact reason, and it has the calculations built in already. These calculations have been around for several generations but might change with the new suspension changes coming to the new motorsports.
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Yeah, that sounds like what I had found and attempted to use with the aforementioned issues.
Unfortunately, I donāt have a good way to deal with spreadsheets at home.
Senistr,
HUGE shoutout to you for the calculator! I use it all the time to set a good start value and then tweak from there.
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I am glad you like it. It was fun to build and I try to keep it up to date and free of clutter as much as I can. Thank you for the support though! I always enjoy hearing from the people it helps.
Itās through Google Spreadsheets, but in any case, the formula is (MaxSpringRate - MinSpringRate) * WeightRatio + MinSpringRate. This is also for the rest of your suspension (Anti-roll, Bump/Rebound Stiffness).
For instance:
Front Weight - 54%
Rear Weight - 46%
Min Spring - 277.9
Max Spring - 1389.5
This information can give you the zero balance. Using the formula I gave you, this would equate to 878.16 Front Spring, and 789.23 Rear Spring. The Antiroll will be 35.56 in front, 30.44 in rear. Rebound stiffness will use the same formula, which would be 11.26 in the Front, and 9.74 in the Rear. Bump Stiffness is slightly different, but the same mechanic. But, you will want between roughly 50-75% of the rebound stiffness. So basically take the rebound stiffness and multiply it by .5 and .75 to get your 50% and 75% and just try to stay in that range. for instance 5.63/4.87 = 50% and 8.445/7.305 = 75%.
Also, if you have an Android phone, google spreadsheets can be used pretty easy. And itās free and open to anyone. But the formula is what everything is based off of. Hope this helps you out a little more.
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The problem with spreadsheets on the handheld devices, when they manage to work properly in a browser AND take less than an eternity to load, is that itās inconvenient to zoom in on every little field to read/input. Much better for this old codger to have a convenient bit of math to do in his head, albeit probably with some quick and dirty rounding. And thanks for that! Iāll give it a shot. Even the method I was trying and to a degree failing with before was proving to be better than the default settings.
No problem. I use to do all the tuning by a notebook and calculator in hand until I got fed up with not having paper near me and just decided to put everything into a spreadsheet which made tuning way, way more easier. At least the formula is a lot easier than what it seems and is pretty straight forward. If you have any issues or need additional help just reach out to me. I have no problem helping out.
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plz ignore or delete
That conventional formula gives spring rates considerably higher than the stock tune values, in my opinion higher than they need to be. In some of my tunes at those settings Iām getting bump steering which makes the car kind of twitchy at high rates of speed. To smooth things out I usually reduce those values proportionally but keep the same percentage distribution.
Iāve heard of spring rate tuning thatās based on resonance, but Iāve never seen any math to do those calculations. Anyone know of a source?
Thatās because the stock settings in this game have always been trash. I know there is a difference however in tuning for Americanās vs everyone else. But there shouldnāt be much of a difference. Iāve played this game with both a controller and a wheel, albeit the wheel horrible sucked in FH4. This formula has been around since FM3 and before hand and since they have never overhauled the actual set ups for suspension, the formula has held strong. I have done every single type of race this game has to offer, as well as others. and with this tuning, i was able to take a 2002 Skyline in cross country events without bottoming the car out, or bounce off the ground on the impacts, so I have no idea what bump steering you are getting with your vehicle.
If you want more information on this, then visit the original article which sums it all up, but remember, this guide was originally created for drifters in mind.
http://web.archive.org/web/20130312174826/http://forums.forza.net/forums/thread/4869639.aspx
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Almost everyone gets this question wrong, but the questionās wording contains the āsecretā. Itās not āspringā, itās āspring rateā; Forza should have worded it so. In Imperial units itās pounds per inch (of compression). In physics itās denoted by ākā.
When you install rally or off road springs, look at the values; very low. Because the travel is higher (ride height). Race springs, which lower the car have a higher spring rate because the spring has ālittle roomā to move before they need to support the mass of the car and any acceleration itās experiencing (F=ma).
So, to get 1000 pounds of peak resistance in a 2" spring (ride height) youād need 500 pounds per inch. With a 10" ride height youād set it to 100 in order to get 1000 pounds of peak resistance (10x100).
You have to determine the best setting for the track or general driving style (off road jumps vs smooth tracks), but the minimum point you can figure out easily is (F spring rate * F ride height)*2 + (Rsp * Rrh)*2 >= vehicle weight. Since the force on the springs increases beyond the carās weight when ever you hit a bump or land a jump, the total from the formula should always be higher than the carās weight.
Shock tuning is affected by spring rate and ride height.
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