Well, I finally got around to attempting this and I must say that the results were amazing.  I dropped almost 2 full seconds off of my laptime at Tsukuba with my TK Skyline.  Amazing imho and with some more tweaking I think that I can get up there with the leaders.

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Keep it clean

Ahh so the difference in values matters more than the actual numbers?
the porsche had 700lb rears STOCK..

Again, the spring rate(what the actual spring is rated at) means very little compared to the wheel rate.  Its the actual rate at the wheels. 

For example, my car originally has a physical motion ratio of .6.  This means for every inch of travel at the wheel, the shock travels only .6 inch.  This value needs to be squared, so, the actual calculated motion ratio is .6^2 = .36.  Take .36 and multiply times 700, and the actual wheel rate is 252 lbs/in. 

While a bit high, this motion ration is not uncommon on some cars.  The calculated motion ration can be very different between front and rear of a car... and the roll ratio and bump ratio can be dramatically different.  I believe this is beyond the physics of this game.  I cant image they have the actual spring motion ratios of every car in the game.  My guess is its all calculated based in a generic motion ratio, or just wheel rate.

I can almost guarantee that the Porsche does not have a 700lb wheel rate.  That would be reserved for a pretty high down force car, and be brutal on the street.  I suspect that the Porsche may have a motion ration a big higher than mine was originally, but the actual wheel rate is probably around 300lbs/in(only speculation on my part)  Most street cars probably have a wheel rate in the area of 200-300ish lbs/inch depending on the weight of the car.

The nice thing about this guide, is it give you a good starting point for spring rates given weight and weight bias...etc.  You are correct in that the ratio is very important, however, in real life, the actual spring rate is critically important to how a car works on the track and transfers to lap times.

My experience is, at least with DOT R and Slick tires with no down force is generally higher wheel rates(which are close to what this guide suggests) produce the best control and lap times.  In my, and all my racing friends experience, have found stiffer springs(and good shocks to control this) are generally faster and easier to control.  This of course has its limits, and requires testing to determine what’s best in real life.. and suspect it applies to this game... but only testing will tell.

 

Interesting find Feltchidious.

Would be great if we could get a mod/dev or something to answers this if this is actually the case...

Edit:
@Progenitor One: Keep us up to date about your findings, if you find out anything new/interesting.

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Gamertag: NitriusX
Playing: Forza 3

I really appreciate the setup help from here, just one problem I'm having:

Am I the only one getting this error when attempting to load the reshirt1701 web calculator (sorry about the hard to read text, this is copied right from my browser window)?

The following information is meant for the website developer for debugging purposes.

Error Occurred While Processing Request

Element OVERALL is undefined in FORM.   The error occurred in /var/chroot/home/content/d/y/l/dylanpedersen1/html/redshirt1701/Forza2/suspensioncalc.cfm: line 16 14 : </style> 15 : <!--- Sets text names to stiffness values ---> 16 : <cfif #form.overall# is .3> 17 : <cfset overalltext = "Normal"> 18 : <cfelseif #form.overall# is .35>

Not to pimp my own wares, if you will, but seeming how red's calculator seems to be broken, you know there is another web based one at http://fm2calc.ruinedmylife.com , right?

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Suspension Calculator Based on feuerdog's guide: (Now Does Metric!)
http://fm2calc.ruinedmylife.com

Is there any calculator where you can use the metric system?

Danhrules got one in his spreadsheet calc: Link
But i'am not totally sure if its 100% right, because there seems to be a bit of a problem with the metric system of some sort, hard to explain, but feel free to try it out. Its hard to make a metric calc when the original setup calc is in imperial. But hopefully soon the bugs with the metric version will be sorted and we will all be happy.

iammatt00, said he would also try to make a metric version of his web calc, but i don't know how far he has come yet.
feuerdog also said he was going to try to add metrics to his original setup(the first post in this topic) but he seems to have a lot of other things to do, so i'am not sure how the progress on that is.

Hopefully we will see a fully functional metric suspension calc soon.

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Gamertag: NitriusX
Playing: Forza 3

Okey. Thanks for bringing me up to speed :)

Nitrius:

Danhrules got one in his spreadsheet calc: Link
But i'am not totally sure if its 100% right, because there seems to be a bit of a problem with the metric system of some sort, hard to explain, but feel free to try it out. Its hard to make a metric calc when the original setup calc is in imperial. But hopefully soon the bugs with the metric version will be sorted and we will all be happy.

iammatt00, said he would also try to make a metric version of his web calc, but i don't know how far he has come yet.
feuerdog also said he was going to try to add metrics to his original setup(the first post in this topic) but he seems to have a lot of other things to do, so i'am not sure how the progress on that is.

Hopefully we will see a fully functional metric suspension calc soon.

VanishingLight:

Is there any calculator where you can use the metric system?

Am working on it, am at around 20% complete in converting the formulas and units of measurements to work with metric system, I'll let you all know when I get it done!

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Suspension Calculator Based on feuerdog's guide: (Now Does Metric!)
http://fm2calc.ruinedmylife.com

CobraRacer,

In my opinion, FM2 seems to use wheel rate rather than spring rate.  Even assuming a pretty generic .5 motion ratio the spring rates get too large in the game to be realistic.  At 2.2 cycles per second on the suspension frequency, for example, the spring rates don't make sense in the game...they are much too large.  I think motion ratio is taken out of the equation and the "sliders" in the game refer to wheel rate.

By the way, is that a Factory Five Spec Racer?  Nice... 

I just looked at the picture again and answered my own question!  I have been looking at the Factory Five's also.  Dreaming about the GTM supercar!

Back to tuning my Viper GTS ACR on FM2!

WRXpilot:

I really appreciate the setup help from here, just one problem I'm having:

Am I the only one getting this error when attempting to load the reshirt1701 web calculator (sorry about the hard to read text, this is copied right from my browser window)?

The following information is meant for the website developer for debugging purposes.

Error Occurred While Processing Request

Element OVERALL is undefined in FORM.   The error occurred in /var/chroot/home/content/d/y/l/dylanpedersen1/html/redshirt1701/Forza2/suspensioncalc.cfm: line 16 14 : </style> 15 : <!--- Sets text names to stiffness values ---> 16 : <cfif #form.overall# is .3> 17 : <cfset overalltext = "Normal"> 18 : <cfelseif #form.overall# is .35>

The calculator is two poorly locked down pages :).

Make sure you start with the input page - http://www.redshirt1701.com/Forza2/suspensioninput.cfm

and not the calculation page http://www.redshirt1701.com/Forza2/suspensioncalc.cfm

start with the second page and it pukes because it doesn't have the inital variables to use.

Hopefully I'll get around to locking it down appropriately :)
Dylan

---

Online Forza 2 Suspension Calculator
http://www.redshirt1701.com/Forza2/suspensioninput.cfm
Based on Suspension Guide by Feuerdog
http://forums.forzamotorsport.net/forums/1/256899/ShowThread.aspx

Lol. I put in numbers out of curiosity and your calculations told me to make a Porsche Cayman(MR) significantly stiffer in the rear...

Did I make a mistake, or does this somehow work in Forza?

Anybody got some tips for a 360 Modena?  I bought it and used the calculator on it and it was great, I loved that car, so naturally I wanted to keep driving it.  The next set of aces I had to do was the semi-pro 600hp races, so I bought upgrades and got the Modena right to 600hp, with full weight reduction and race tires, and forza 2 body kits for downforce.  Well, after recalculating and applying the settings, I cannot get this thing to handle at higher speeds.  Low speeds and even in and out of corners it still feels great, once I am on a long straight though, look out.  It starts rocking side to side and eventually the back end slides out from under it.  ANy suggestions?  I have tried adjusting more downforce and lowering the PSI on the rear tires to 28 and 29 on the front.  Any other help would be appreciated.

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All times are Eastern Standard Time (GMT -5:00), unless otherwise noted.
[Mod edit: Sig size exceeds forum limits, 480x115 pixels max - D]

This is for the OP.

 

I recently opened up a new website dedicated to tutorials, race and drift setups, and anything else I can find. I would love to post your calculator up on the site. Would you mind? Or anyone else that has an opinion on which one of the numerous ones I’ve seen today mind telling me witch is better? I would like to at least make a link with a little blurb about it on my site. Thank you

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Now with over 40 drift setups!!!!

Semple - Yes.  Keep in mind it's not just the front or rear spring value,.....it's the ratio/relationship of front-to-rear that keeps the car balanced. 

Alpizzle - I'll have to build that setup myself to see what is happening.  It's possibly a stabilty issue with the toe settings at high speeds.  Try a front toe of 0 and a rear toe of -.2 and see if that sorts it out.  On a side note, I began testing the Ferrari 355 Challenge last night and I was very happy with the results, I need to verify the damper values with the guide before I change anyhting, but it's gonna handle very well.

Tech - Be my guest, just give me the credit and keep in mind there are some changes and updates coming. 

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

Here are some of the guide revisions i'm working on right now:

1.  An addition to the weight distribution modifiers for a "more responsive", less stable spring set.

2.  The antiroll bar values are generally too high, the neww multiplier will most likely be .22(not .25).

3.  The RR and RA distribution modifiers are wrong,.....still working this one out but it'll probably involve removing spring strength from the rear(not adding to the front), spring values are too high.

4.  The damper rebound ratios are just a tic off in a few places, still testing to confirm.

5.  Aerodynamics are having an impact on high speed balance, this addition will be delayed further.

6.  High speed stabilty testing might have an effect on Toe ettings, but for now they should be OK.

7.  I ran into some AWD diff. tuning, tire temperture issues last night.  Probably just related to suspension settings, but possibly due to locking balances.  No changes more than 5%.

 

I'm going to save these up for now and try to keep the changes bulked up together, so that those of you who have made spreadsheet calculators don't have to constantly update everything.

The work on a metric conversion is on hold for now, sorry guys.  As soon as i'm happy with the the calculator I will get this conversion done.  If it makes you UK lads feel any better my mother is English, my brother is Scottish, and I lived over there for over 6 years, so I know all about Blue Peter, Horlicks, Danger Mouse, The Young Ones, and Monster Munch.

The gear tuning calculator is coming along slowly,...but it is working so far.

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FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/

Just wanted to add my thanks to all the others for your work. Been able to tame cars I had given up on. many thanks!

feuerdog:

Alpizzle - I'll have to build that setup myself to see what is happening.  It's possibly a stabilty issue with the toe settings at high speeds.  Try a front toe of 0 and a rear toe of -.2 and see if that sorts it out.  On a side note, I began testing the Ferrari 355 Challenge last night and I was very happy with the results, I need to verify the damper values with the guide before I change anyhting, but it's gonna handle very well.

Feuerdog

I will try those changes when I get home.  If that doesn't straighten out the problem, if you are interested in what is going on I can gift you the car to test out, just send it back whenever you are done, I wouldn't want someone to spend credits building a car just to answer my question.  If that's okay with you let me know.  I'll let you know how the toe settings affect the high speed handling.

Thanks again.

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All times are Eastern Standard Time (GMT -5:00), unless otherwise noted.
[Mod edit: Sig size exceeds forum limits, 480x115 pixels max - D]

I will eventually own every car, so it's not a big deal to buy it,....and I have a hefty euro discount now anyways.  I'm just not sure I have the car unlocked yet.  Money is relatively easy to accumulate.

You say the car is getting squirrely on the straights?  Or on high speed corners?

A stiffer spring combo will tighen things up too, and the dampers will follow suit.  The only other thing I can think of that would unbalance the car is the Aero.  A high front downforce compared to the rear could make the rear want to wander a bit.  And very high downforce loadings in general will affect your camber ratios.  Try lowering you camber by .1 for every 100lbs of downforce on that end of the car, but only if the toe adjustements don't work. 

Example: 

150lbs front downforce = add .1 to front camber = -.6 would become -.5

220lbs rear downfoce = add .2 to rear camber = -.8 would become -.6

 

---

FM3 Suspension Calculator
http://forums.forzamotorsport.net/forums/thread/3073197.aspx

iPhone Suspension Calculator
http://forzatune.com/

Learn about Tuning at DIY RaceTuning
http://diy-racetuning.net/