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slogun1993

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#1   2012-01-25 12:22          
# carbon1993 : Ok guys, im into FM since 2010. Finally i found out some things in tuning for grip that i haven't found on the whole internet.

First of all i want to thank Rawr D1n0sour for his awesome damping method:
http://forums.forzamotorsport.net/forums/thread/3827077.aspx

And VVV Worm for his hard spring method:
http://forums.forzamotorsport.net/forums/thread/5011868.aspx


This Tuning Guide Will contain the following:
-How to drive and to identify handling (explained as last per tuning a part).
-Common mistakes while tuning and driving.
-The definitions of tuning those parts.
-Handy tricks for tuning.
-Tuning settings from leader-boards and pro's (just hard or soft settings etc.).
-And hopefully no spelling faults.

Before getting started some important:
-This whole guide and experience is done in metric. (so i don't know if it will work with English standards).
-A happy tune is no tire squealing during cornering. (you may hear it but not too loud).
-This is tested all on R3. (but this should work on every class)
-I am not responsible for bad tunes. (everybody tunes diffrent and has other likings)
- I recommend using no AID because it takes away feeling and power.

So that said lets get started.


Springs
So lets start with one of the hardest things. Springs are set in kgf/mm to me and other experts it means Force it needs to Compress. So the harder the setup the more force it needs to compress the springs. The maximum the spring can compress or extend is -5cm or +5cm (this is standard no matter what class). That was the definition of the springs.

Now let's get to the caristics.
-Hard springs: more response, more allowed force, slow and less movement and last less bump absorbtion.
-Soft springs: less response, more weight transfer, fast and more movement and last more bump absorbtion.

I usually use the softer springs. Just because it allows to push more weight on the tires which widens the tire contact patch. It also absorbs bumps better. Which means less nervous movement, less tends to slide and you can drive over curb stones without losing to much grip.

Hard springs usually good for slow corners and a track with a lot of them for example Fujimi Kaido. Because of the many corners following each other the chassis must be quick and responsive. (it must settle the chassis quick in the corner)

Soft springs for normal tracks it is the exact opposite of hard.

Common mistakes are way to soft or way to hard. It needs both so a good setup is having the precise right mixture of hard/soft.

How to tune it:
For the soft setups i use my own method.
Example:
I have a Mosler MT900R. It weighs 972 Kilogram has a weight distribution of 41% front. It can create a 1,335G.

Now a simple calculation:

Step 1
car weight x weight distribution front= static weight on front
972 x 0.41= 398,5 Kg

Step 2
static front weight x (g force+0.05) = spring setting : allowed spring movement= Forza spring setting
398,5 x (1.335 + 0.05)= 551,95 : 10(always ten)= 55,2 kgf/mm

do the same withe rear which would be 972 x 0.59= etc. etc.

Another method i found for harder springs
(Car weight+ downforce at front-rear) / 100 x weight % at front-rear / ride height at front-rear x G-force = YOUR SPRING RATE



Damping
Ok this is a bit difficult because this is just numbers. I little know about this damping but here is what i know:
Hard damping: slow movement, quick responsive steering and bad absorption.
Soft damping: fast movement, slow responsive steering and very good absorption.
Rebound and bump isn't really that important to me if you have a good bump your rebound is between 50 and 75 of the bump.
it is hard to tune it correctly. I mostly stick to the softer settings just because of the absorption. I also found out that low bump can improve grip it really shaves of lap time. But beware it needs a several amount to work so you cant set it on 1.



I found a very good way on the internet to tune this:

Here is the method I use to set a good starting point for damping:

1. Multiply car weight by 1.6, Divide by 1000, round the the nearest single digit. This is the overall bump damping.

2. Multiply the front weight percentage by 0.9 Then divide by 100.

3. Multiply this number by the overall bump from step 1.

4. This is the front bump damping. To get the rear, subtract the front bump damping from the overall dump damping given in step 1.

5. Now to find the rebound you multiply the bump damping by 2.5



For example I'll use Acura RSX, it weighs 2820lbs and has a front weight of 61%

2820*1.6=4512=4.512=4.6 (Overall bump),

61*0.9=54.9 54.9/100=.55

.55*4.6=2.53=2.5 (Front bump).

4.6-2.5=2.1 (Rear bump).

2.5*2.5=6.25=6.3 (Front rebound).

2.5*2.1=5.25=5.3 (Rear rebound).

Hard and soft same with springs hard for slower and many corner tracks. and soft for normal and GT tracks. etc.

Common mistakes are having a too high rebound and or bump. Again it needs soft and hard to work(depending on track). You need to stick between the 50-75% rule for the bump. Having a really weird hobble after driving over a bump is always a damping problem.



Tires
Tires are the ones that transfer the grip. Lower settings more grip more contact patch. Higher settings less grip more responsive less contact patch etc. I usually run my tires around 2.21Bar hot. Depending on the weight distribution, the side with less force always run it a bit softer to equal to contact patch. Again too low is bad too hard is bad too. High settings hot tire middle. Soft settings hot tire outsides.



Aligning
Lets start with Camber. Set Camber always to a negtive a positve doesn't help. How to set your camber? Easy run a few laps and watch your telemetry. If your tires too hot on the insides it means you have to much negative camber. Tires too hot on the outsides means not enough camber. If your camber is setup right it should be within 10 degrees Celsius from outer to inner of the tire.
the way you should look like: (.) 0 (.) (.)=car tire 0= car center .=tire middle the ( or ) pointing to the 0 are the insides!

A good camber setup should give a result like this: (=97 .=95 and the )=93
A bad camber setup should give a result like this: (=97 .= 90 and the )=96

That done you should look at the other tire diagram. If your camber shows + during a corner you need to set your ARB and then begin all again for aligning. Peaks of +0.2 are normal and doesn't affect the grip. Also make sure that you make difference between elevations and curb stones and a wrong ARB/Camber setup. It is normal to have +camber on bad parts of the track.


Toe
Toe you us only for stability or response. +toe will bring your car a better response. -toe will add stability.
If your car is unstable ONLY ON STRAIGHTS you should add a bit of -toe mostly to the back wheels. If your car is stable you can add some +toe. +toe in the front is better corner in. +toe rear is better corner out. Toe can effect the tire heat so watch out. It maybe you need to adjust camber a bit


Caster
Caster is the angle of the spring compared to the 0 stand. The springs are always leaned to the back of the car. This angle brings stability during driving ( so your steering wheel doesn't hobble from left to right during straights). The angle also gives a better stability on braking by compressing the spring. Having this angle can adjust your camber during cornering. Just watch it changing the camber during stand stills. This can be advantage or a dis advantage.

High caster: great stability also during braking, big camber change while steering and slow steering responsive.
Low caster: bad stability, bad braking , less camber change, good steering responsive.

I usually set caster between 4.2 and 7.0

ARB, camber, toe and caster can all influence your camber and tire heat. So it need all needs to be adapted to each other.



Anti Roll Bar (ARB)
ARB's are hard. i don't have any trick for this. You need to tune it by feel. And yes it is very hard! That's why it is tuned after almost everything else. Although i found out that higher ARB's mostly will shave of time. ARB ties the left spring to the right spring.
ARB's all need to be tuned by feel. Know when your car has to many ARB if it pushes to the corner. Low ARB most likely will get a sloppy understeer response

High ARB: quick responsive and more load less weight transfer.
Low ARB: slow responsive less load more weight transfer.

You can tune ARB by setting the Front And REar ARB to 20. Setup the front ARB if its to stiff decrease with 2 if to soft increase with 2. If the front doesn't push or under steer continue with the rear ARB. The rear ARB is too hard if it oversteers to soft when it grips to much on the rear. You will find the best setting.

Don't set these settings to high it can cause to lift the inside tire while cornering. And don't set them too low.
Forza says the lower the more grip this is right but having grip settings on the ARB can ruin your cornering because of gripping too much. Which can throw you of corners. It needs to be high enough but not too high.


Braking
Just set the braking to the front for more stability and braking force because of weight transfer.
People say the braking should be adjusted to the rear probably never heard of weight transfer.

Braking force
This part doesn't really matters if you don't use ABS. More force is more responsive less doing footwork on the brakes.
Low is more footwork on the brakes. I would just set it 99% just because i can. It doesn't matter if it high or low it doesn't affect the braking power. Its just all personal likings. If you use ABS don't set it too high. Because ABS takes braking power away.


gearing
Gearing is actually simple. Short gears better acceleration. Higher gears higher top speed. On tracks you would like to achieve to highest speed possible! You can achieve this with shortening gears so it would almost touch the rev limiter on the fastest part of the track.

Tip: set your 1st gear lower so you get a better launch and a shorter gear. When you shift up to 2nd gear it should stop spinning rear wheels. So limited wheel slip on starts will have a good launch. Means faster start and out driving any noob.



Differential
Differential allows the speed of the inner wheel while cornering. It determines how much percent of the speed between the wheels may difference. The settings mean actually how quick the wheels lock. So more percentage is quicker lock. The best way to tune is dropping the percentage till you have no wheel spin anymore going out corners.

I set these between 28 and 40 procent on acceleration depending on track.
The percentage deceleration can vary. I should set them to -5% at least compared to acceleration.

Actually you need to tune them by feel. But that is way to hard!

If your slipping or sliding out of exit of a corner you have too much difference between accelaration and decelaration.


Added 2 minutes later:

this gets updated

Jesus Christ

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#2   2012-01-26 18:49          
nice guide!
Why be a KING when you can be a GOD?!

slogun1993

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Posts: 119

Location: Netherlands
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Age:
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#3   2012-01-27 19:22          
thanks!! need to update and explain tuning and parts. maybe that comes tommorow.