Gran Turismo Math

  • Thread starter parts_guy
  • 14 comments
  • 2,848 views
P

parts_guy

3
Hello all! I got bored last night and started playin GT again and have been playin 4 all day today... Was wondering if anybody on here could help me with something... Several years ago, back in the GT2 days I ran across a tuning website that had several "formulas" for tuning cars... I wrote them all down but have since lost the notebook I wrote them in... The only one I remember is the spring rate/bound/rebound formula (which I will gladly share if anybody wants) that I've used religiously since finding it. The site had formulas for gear ratios, LSD, aerodynamics etc... Just wondering if anybody has ran across this site in their GT journey or knows of any other "formula" sites...

Thanks
LarryD
 
I've not seen any tuning formula ever be worth using everywhere. I have things that I generally use as a baseline but that's all.

I'd be interested in these "formulas" just to know what they are and to see if they actually work.
 
Likewise with RJ. Indeed, I'd be interested to see if these remembered formulae are mine as I did an awful lot of number crunching along those lines in times gone by :D
 
The only one I remember is the one for Springs/Bound/Rebound... I use it for all my cars.

It goes like this... Multiply your Spring Rate by .5 to get your Bound, multiply your Spring Rate by .3 to get your Rebound...

Obviously not for everyone, but It's how I get my settings and it's worked for all these years.

The site had much more info and formulas but the site is no longer up apparently...
 
parts_guy
The only one I remember is the one for Springs/Bound/Rebound... I use it for all my cars.

It goes like this... Multiply your Spring Rate by .5 to get your Bound, multiply your Spring Rate by .3 to get your Rebound...

Obviously not for everyone, but It's how I get my settings and it's worked for all these years.

The site had much more info and formulas but the site is no longer up apparently...
Click to expand...

The majority of tuners around here (in my experience) use a stronger rebound than bound. Also, the front/rear ratio seems to be just as, or more important, than the bound/rebound. Eg you'll see numbers like 3/8 and 6/2 bound and rebound, where you can see the tuner trying to manipulate the weight-shifting through the shocks.

I have seen a formula on gtplanet that calculates minimum spring rates based on car weight and perhaps hp. Never used it cause I hate maths and am a crap tuner anyway. If RJ and Suker haven't heard of it there's a good chance it's not worth finding, but I honestly can't remember who posted it or where I read it.
 
I'm wondering if the "formula website" you're talking about was granturismoforum.com. If so, you're out of luck...that site is long gone.

You'd have to talk to one of the guys who've been playing GT for years--Pupik, sportwagon, maybe slowman...one of those guys.
 
Boundary Layer
Test drive at GVS
First step: Turn off all Driver Aids.

I did 6 laps to gain an understanding of my starting point and what I might want to touch up in the future. The rear of the car steps out pretty well. The dampers are set too stiff for me – the car is a little jumpy over curbs and has a pretty heavy steering feel.

Ride Height:

I reduced the ride height to: 98mm (from 115) front and rear. I came to this value because it should leave the suspension with sufficient stroke (still more than 10mm above the minimum ride height), and the tires still fit in the fenders.

Spring Rates:

Default settings are 6.4kgf/mm front, and 5.8kgf/mm rear.

Earlier I reduced the vehicle’s weight by 15.04% (calculated by 1 – 1062 / 1250).
So I’ll decrease the spring rates proportionally. But, I’ve also reduced the ride height 14.78%, so I’ll increase the spring rates a proportional amount. As a precaution against running out of suspension travel, I’ll bump up the spring rates by 0.1kgf/mm after these two adjustments.

Front: (6.4kgf/mm)(1062 / 1250)(2 – 98 / 115) +0.1kgf/mm = 6.341 ~ 6.4kgf/mm [always round up]
So, I guess I’ll leave the spring rate at 6.4kgf/m [funny…]
It’s the same story at the rear of the car. I leave the rear spring rate at 5.8kgf/mm

[note: I know that math isn’t for everyone, I really only do it for my own peace of mind. If you would rather adjust your spring rates purely based on feel, that will work too. I end up having to do that in my next step anyways]
Click to expand...



That's the closest thing I have heard of math in Gran Turismo. It would also be a pain to tune that way.
 
A formula would be a thing only for each individual driver, I would assume.
It would only work if the cars drive type, weight balance and wheel track and wheel base were all the same, surely.
Weight balance varies the spring and damper so much. As does drive type, even if you got the 2 cars with 50-50 weight balance, 1 FWD and the other 4WD the suspension set up can be extremely varied. Even the position of the driver, as in how far forward or rearward he sits can change the style, then in-turn the setup.

Possibly the most relevant item is power, as the faster you go the more resistance you need to push back against the forces of momentum.
So the same car with a power upgrade will require a revised setup.

A formula would have to be would be very complex and time consuming to work, so you would probably be quicker with a trial and error method anyway.
All in all, I don't believe there could be 1 formula to use.
 
Last edited:
I know of a site called GTVault.com. They have many setups for every single car in the game that users submit. and every car has at least 3 different setups for drifting, racing, etc.
 
Well numerous hours of searching last night have led to frustration... I do remember that a lot of the formulas were based on real life calculations that I keep running across in my searching... I'll keep looking and try to start converting what I've found so far...

Thanks to all that have replied!

LarryD
 
All of this is ringing a bell. I seem to remember a site like you were talking about.

Back in my GT days, back when PD seemed to be trying to simulate what happens when a car actually bottoms out over bumps (it's worse than a set of sparks...in the 1st game, your car actually loses speed). I came up with a formula for the spring rate that had something to do with how much travel there is, and combined it with how stiff the springs are.

You have to take into account the weight of the car, and you have to know what its real-life weight distribution is. A front-drive car, for instance, will have lots more weight (usually over 60% of it) located towards the front.

Once you know the weight distribution, you have have to look at the springs. If they're set at 3.0 kg/mm, this means they can resist 3 kilograms for every millimeter of spring travel. 💡 You multiply this by the total amount of travel...so if there's 155 millimeters of ground clearance, there is (theoretically) 465 kilograms of support offered by that set of springs during a complete stroke of that spring.

Obviously, if you lower the car, the spring will need to be stiffened if the car is not to bottom out.

Anyways, I came up with a matchbox calculation for all this, but I no longer use it, since cars no longer bottom out in games later than the first GT. :indiff:
 
Parnelli Bone
All of this is ringing a bell. I seem to remember a site like you were talking about.

Back in my GT days, back when PD seemed to be trying to simulate what happens when a car actually bottoms out over bumps (it's worse than a set of sparks...in the 1st game, your car actually loses speed). I came up with a formula for the spring rate that had something to do with how much travel there is, and combined it with how stiff the springs are.

You have to take into account the weight of the car, and you have to know what its real-life weight distribution is. A front-drive car, for instance, will have lots more weight (usually over 60% of it) located towards the front.

Once you know the weight distribution, you have have to look at the springs. If they're set at 3.0 kg/mm, this means they can resist 3 kilograms for every millimeter of spring travel. 💡 You multiply this by the total amount of travel...so if there's 155 millimeters of ground clearance, there is (theoretically) 465 kilograms of support offered by that set of springs during a complete stroke of that spring.

Obviously, if you lower the car, the spring will need to be stiffened if the car is not to bottom out.

Anyways, I came up with a matchbox calculation for all this, but I no longer use it, since cars no longer bottom out in games later than the first GT. :indiff:
Click to expand...

What your saying is correct, but the value of the springs cannot be directly compared to weight of the car, simply because there is leverage on the springs, so even though you have example 500kg on the front wheels, you cant tune the springs for that value becuase you need to know the actual force after considering the leverage on the springs.
Thats why these things can be transferred from car to car, because each suspension geometry is different.

For me any kind of maths (in a video game) is useless... tuned a car for its feeling and correct the handling problems it has simple... trial and error.
 
Gt4 maths is easy. 255bhp, 607kg Lotus Elise Sport 190 with wing and S3's = quicker than Tommykaira ZZ-S with 311bhp, 627kg with wing and S3's. :D which is actually annoying, because I like the Tommykaira more. :irked: :odd:
 
Last edited:
But Leo, you aren't looking at the torque. If the Elise has more, then of course it's going to wipe the floor with the TK.
 
The Elise has approx 250nm of torque, and TommyKaira has almost 300nm of torque. Tommykaira also has 6-speed tranny against Elise's 5-speed tranny. I'm just as baffled as you are, the TK should be superior. I even gave them exactly same settings, other than gearbox-wise, and TK felt more understeery. :odd: result of shorter wheelbase of the TK, perhaps?
 

Latest Posts

Back