DIY-racetuning - The Ultimate Forza Motorsport 3 Tuning Resource

I have a good question. Is there a way to calcuate how much down force you need on a car? And do you need to readjust your springs to compincate for the added weight ? I am building a S class GTR (2010 GTR to be exact), and I added the front Forza aero due to the car always wanting to push all the time . I just want to know if there is a formula to figure this out.

I am running with:
All racing Drivetrain
Sport wieght reduction
Race ARB
Race Springs
Race Flywheel
Sport Intercooler
Race Cams
Race Exhaust
Rims: TSW-traskstar 4
Forza front bumper and everything else is set up with the Wald body kit

Tire PSI
F-29.0
R-29.5

Camber
F- -1.0
R- -.09

Toe
F- 0
R- -.01

Caster
5.0

ARB
F-22.90
R-24.90

Springs
F-786.0
R-854.5

Rebound
F-6.7
R-7.3

Bump
F-4.7
R-5.1

Braking
balance - 40%
pressure- 90%

Diff
F- accel - 46%
deccel- 0%
R-accel- 66%
deceel- 56%
Center - 75%

Aero-
F- 108lbs
R- 0

Any help would be awesome, thank you.

No. Basically you just have to try and re-tune and retry to find out what works the best. Tskuba will require different downforce settings than Mugello, and Sebring will require different settings than Ladera.

Gotcha, so I should go by feel for each track. Should I also modify the spring and ARB's as well ?

I wouldn't adjust the ARBs.

With the springs, you may need to stiffen them up, but only if you notice the car "bottoming out". Just check the spring telemetry page to spot this. Otherwise leave them alone too.

As for the question of how much downforce to use, first get the balance between front and rear right. You can then work on the total downforce amount by doing a few laps, then increasing/decreasing downforce (remembering to keep the balance between front and rear the same), and noting the effect on your laptimes. Trial and error basically!

I will try that out donpost , thank you . I sat down last night and some laps in the car , I beat my own lap times by at least 1 - 2 sec . I did Suzuka full in just 2:05, it put me up to at the top 9% of the leaderboards . But I will keep testing out the car and playing with the downforce . Thanks again.