Weight Distribution Questions

B

bostwick_965

34
First of All Gt4 uses real life Front/Rear weight distributions. In every guide including real racing guides this is a very important factor for tuning. I would like to find weight distributions for most of the cars in the game to help me more precisly balance my cars. So is there a method of actually finding the weight distribution in the game or do I have to look on the internet. Yes I have found very few on the internet but most are not unless im looking in the wrong place.
I also think that a detailed page were everyone could post actual Weight distributions would help. I don't know but just thought id throw it out there. But please gice me a few pointers on where to find them. If I get a good response mabe Ill try to post a bulk of the real life Weight distributions on GTP. I hope i'm not the only person trying to find these to help tune.
 
B_B_B
which tires lock up when breaking has more to with weight shift and brake settings than total weight distribution
Click to expand...
In other word, wrong brake balance controller setting because using wrong weight distribution reference or wrong calculation , right?
 
Weight distribution, transfer and brake bias adjustments - some of my favorite subjects.

As far as static weight distribution for particular cars you will not find anything in GT4 itself (which is a real pain), however google is you're friend here. I have never had any problems finding static weight distribution figures in this way, just google on the cars full name and the words weight distribution.

Then you may want to have a look at the following threads here at GTP

GT4 and Brakes

Setting The Brake Balance Controller

GT4 Suspension & Brake tuning guide

Guide to weight transfer and spring stiffness by Greyout


Greyout's guide to spring stiffness and how to set the brake balance controller are both included in the GT4 Suspension and Brake tuning guide, so downloading that may well be a good start. Particularly as it has a lot more pictures to illustrate what is going on with regard to weight transfer under braking and cornering, which always helps.

Hope it all helps and any questions, please don't hesitate to ask.


Regards

Scaff
 
All those guides are highly recommended, however; You can´t beat the feeling! Since tuning a car is a highly personal preferance, the way the car feels for YOU, must be essential, weather the suspension , brakes or weight distribution is spot on or not. Use these guides as they are intended; guides to YOUR best setup!
 
I've always found that the front to rear ratio of the spring rates on default racing suspension closely match the manufacturers weight distribution claims, which is why I like to keep this ratio when suspension tuning.

It may not be a great assumption, but I'd say it's a fair guesstimate.. :D
 
RXGem
I've always found that the front to rear ratio of the spring rates on default racing suspension closely match the manufacturers weight distribution claims, which is why I like to keep this ratio when suspension tuning.

It may not be a great assumption, but I'd say it's a fair guesstimate.. :D
Click to expand...

As far as a rough guide goes its not far off the mark, something I tend to do as well when setting a car up for the track (i.e. before tuning for balance).

Regards

Scaff
 
@bostwick_965, do you still interested in finding weight distribution?
We can estimate the car weight distribution by measuring the body roll angle in the front and rear tire. I use photoshop to measure the angle, with measuring tool and ALT key.
I find that on FF or classic muscle car which supposed to have heavier front, the angle ratio is more toward the front compare to perfectly balance reference car. On RR or MR or family wagon car which supposed to have heavier rear, the angle ratio is more toward the rear. And in some extreme case the rear body roll angle is bigger than the front.
I measure the car using equally soft spring rate and equally high ride height.
 
^is that really a good way? I thought weighttransfer happened no matter how you set up your suspension, so checking distribution by looking at bodyroll may not be very accurate. Maybe I´m wrong here, so please explain what you are doing in more detail.
 
Team666
^is that really a good way? I thought weighttransfer happened no matter how you set up your suspension, so checking distribution by looking at bodyroll may not be very accurate. Maybe I´m wrong here, so please explain what you are doing in more detail.
Click to expand...
How about this, no matter what spring rate and ride height combination that I use, the ratio between front and rear body roll angle only change a little
This is what I do
Body roll angle of some GT2 car
Code: 
car                  angle
                 front    rear
Evo II            3.6     2.2
Gts-t Type M      2.7     2.2
156 V6            2.6     0.9
Forester          3.3     4.1
Elise             0.0     0.5
V8 Vantage        3.2     1.8
XJR               2.9     1.1
Musclecar         2.9     1.4
Midget            2.3     0.0
Gts4              2.5     1.0
Cougar            1.7     0.6
BTR II            3.8     3.7

I still testing some more car.
 
Ok. but how do you test it? Acceleration/braking or turning? Or both? I can´t see how you can get anything useful from this, since bodyroll will be affected by too many factors. Are the cars fitted with racing suspension? Is anything else tampered with on the cars? For the most accurate testing, cars should be left stock, to get a more exact and "real" measurement. That probably screws your idea, since the different cars won´t have the same stock suspension. The distribution will still happen, but bodyroll will not be an accurate measure. Please elaborate further, as this is interesting.
 
I do cornering test. Yes, body roll will be affected by many factor, the body roll angle can be changed with some tuning, but the ratio between front and rear will stays the same if you treat front and rear the same way. Even if you use extreme high for one part, the ratio will only change a little.
Will this answer your question?
Code: 
 car    weight  spring   height    damper stabilidownforc tire f angler angle
Cobra    2299    2/2     150/150   10/10    1/1   34/53    N     5.6    4.3
Cobra    2299    2/20    150/150   10/10    1/1   34/53    N     3.3    1.9
Cobra    2299    20/2    150/150   10/10    1/1   34/53    N     1.3    0.6
Cobra    2299   10/10    150/150   10/10    1/1   34/53    N     3.0    1.5
Cobra    2299   20/20    150/150   10/10    1/1   34/53    N     3.2    1.4
Cobra    2299    2/2     120/120   10/10    1/1   34/53    N     3.8    1.5
Cobra    2299    2/2      95/95    10/10    1/1   34/53    N     2.4    1.0
Cobra    2299    2/2     150/95    10/10    1/1   34/53    N     2.9    1.1
Cobra    2299    2/2     95/150    10/10    1/1   34/53    N     3.8    1.7
Cobra    2299    2/2     150/150   10/10    1/1   78/99    N     4.4    3.0
Cobra    2299    2/2     150/150   10/10    1/1   34/53    SS    4.9    3.9
Cobra    2299    2/2     150/150    1/10    1/1   34/53    N     3.9    3.4
Cobra    2299    2/2     150/150    10/1    1/1   34/53    N     5.4    3.8
Cobra    2299    2/2     150/150    1/1     1/1   34/53    N     4.1    3.5

Originally, I want to see what affecting body roll angle, and then see if I can change the body roll ratio. I failed to notice other tuning that can change body roll angle other than spring rate and ride height.

someone can translate this (theory book)? what factor influence body roll ?
A Study of the Effect of Various Vehicle Properties on Rollover ...

I test some new toyota car and the result seem to support my theory
Code: 
car                     angle
                    front    rear
Altezza RS200        1.6     0.9
Lexus GS 300         1.2     0.0
Caldina GT-T         1.6     1.5
Celica SS II         1.0     0.0
chaser tourer V      1.9     1.0
corolla levin        0.6     0.0
MR2 GT-S             1.3     1.9
Prius                1.2     1.3
starlet glanza       2.0     0.7
supra rz             1.8     0.0
yaris                1.2     0.0
soarer 2.5vvti       1.8     1.2
 
Hi S ... it's been a while since I read that one :D. Nice to see you exploiting the resource that the net is for such material my friend (I can't remember if I ever sent you a batch of links or not?).

Which part of the paper are you stuck on?
 
Perhaps the GT physics are not advanced enough to account for more factors than springs and rideheight, but IRL you would have to account for damping, speed, downforce, front/rear weight distribution, center of gravity, chassis stiffness, car width, stabilisers, traction control and active stability management systems, differentials and probably even things like tyres and roadsurface.
GT physics are also somewhat flawed in the manner of wheel lift and the fact that a roll is impossible. Trying to get a full rollover from simply turning (and in any other way for that matter), will only result in either massive understeer or a spin.
But thank you, that was informative.
 
sukerkin
Which part of the paper are you stuck on?
Click to expand...
My mistake, I download the wrong file from http://www.eng.auburn.edu/~dmbevly/gavlab/pub-pre/pub-pre-03.htm.

This file is more understandable.
A Study of the Effect of Various Vehicle Properties on Rollover Propensity

Please correct me if I am wrong, this is what I conclude (from the book):
  • spring rate, ride height and damper prevent rollover or reduce body roll. It seems my test also show GT emulate this. Lower body roll angle happens when using higher spring rate or lower ride height or lower damper (not notice before).
  • can't conclude tire effect.
  • understeer car have less body roll
  • faster cornering put more weight to the front
  • more front weight decrease body roll angle (this from Using Scaled Vehicles - ACC Presentation.pdf book)
  • body roll affected by CG height (up/down) and longitudinal location (front/rear?)

Team666
But thank you, that was informative.
Click to expand...
Too bad I can't test how balast will affect body roll angle ratio.
 
sucahyo
Please correct me if I am wrong, this is what I conclude (from the book):
  • spring rate, ride height and damper prevent rollover or reduce body roll. It seems my test also show GT emulate this. Lower body roll angle happens when using higher spring rate or lower ride height or lower damper (not notice before).
  • can't conclude tire effect.
  • understeer car have less body roll
  • faster cornering put more weight to the front
  • more front weight decrease body roll angle (this from Using Scaled Vehicles - ACC Presentation.pdf book)
  • body roll affected by CG height (up/down) and longitudinal location (front/rear?)
Click to expand...

longitudinal location could mean where along the cars centre line most weight is seated, ie probably where the engine is located, and in context, that seems likely.

sucahyo
Too bad I can't test how balast will affect body roll angle ratio.
Click to expand...
yeah, that would be interesting to see in GT. Would the suspension compress from the extra weight while the car is standing still? And if so, would body roll decrease, due to extra weight? And furthermore, would it be possible to increase bodyroll by placing the weight to the rear?
 
Team666
GT physics are also somewhat flawed in the manner of wheel lift and the fact that a roll is impossible.
Click to expand...
I found this picture interesting (when testing using extreme tuning).
As RUF BTR2 have heavier rear, bigger rear body roll angle, fitting hard front spring rate make the inner front wheel lift :). The track is highspeed ring, first corner.


This means that we can lift the inner wheel, but PD doesn't provide us with enough tuning range to do that.

Team666
longitudinal location could mean where along the cars centre line most weight is seated, ie probably where the engine is located, and in context, that seems likely.
Click to expand...
I see.
Team666
yeah, that would be interesting to see in GT. Would the suspension compress from the extra weight while the car is standing still? And if so, would body roll decrease, due to extra weight? And furthermore, would it be possible to increase bodyroll by placing the weight to the rear?
Click to expand...
I currently test with extreme tuning to find which tuning can change the front/rear body roll angle ratio the most. Maybe we can see how body roll angle ratio relate to handling. I suspect that tuning which can change body roll angle ratio more will have the most effect on car handling (understeer/oversteer).
I also suspect that there is some connection between body roll angle ratio and the stock car handling.
If, maybe, the normal handling car have body roll angle ratio 3:2, then, maybe, car with body roll angle ratio 2:1 have understeer characteristic, and, maybe, car with body roll angle ratio 1:1 have oversteer characteristic.

Code: 
    car     DT   spring  height   damper    tire  f angle r angle 
 RUF BTR2   RR  0.2/0.2  250/250   10/10    N/N     6.1     7.6 
 RUF BTR2   RR   0.2/20  250/250   10/10    N/N     2.1     1.7
 RUF BTR2   RR   20/0.2  250/250   10/10    N/N     2.5     1.1
 RUF BTR2   RR   20/20   250/250   10/10    N/N     2.5     1.9
 RUF BTR2   RR  0.2/0.2  250/50    10/10    N/N     5.1     5.4
 RUF BTR2   RR  0.2/0.2  50/250    10/10    N/N     5.5     5.9
 RUF BTR2   RR  0.2/0.2   50/50    10/10    N/N     4.8     4.3
 RUF BTR2   RR  0.2/0.2  250/250   10/1     N/N     6.0     7.0
 RUF BTR2   RR  0.2/0.2  250/250   1/10     N/N     6.4     7.6
 RUF BTR2   RR  0.2/0.2  250/250    1/1     N/N     6.1     7.5
 RUF BTR2   RR  0.2/0.2  250/250   10/10    N/SS    7.0     6.4
 RUF BTR2   RR  0.2/0.2  250/250   10/10    SS/N    5.9     7.1
 RUF BTR2   RR  0.2/0.2  250/250   10/10   SS/SS    6.3     7.0

Seeing this test, using harder front spring rate should make the car understeer, but in the game harder front spring rate make the car oversteer. Maybe harder spring grip overcome weight transfer grip.
 
sucahyo
I found this picture interesting (when testing using extreme tuning).
As RUF BTR2 have heavier rear, bigger rear body roll angle, fitting hard front spring rate make the inner front wheel lift :). The track is highspeed ring, first corner.


This means that we can lift the inner wheel, but PD doesn't provide us with enough tuning range to do that.
Click to expand...

Cool, how about FF cars, mainly under braking? The outer rear wheel should lift off, but as far as I know, it´s not doable. At least not in GT3 or 4.

sucahyo
I currently test with extreme tuning to find which tuning can change the front/rear body roll angle ratio the most. Maybe we can see how body roll angle ratio relate to handling. I suspect that tuning which can change body roll angle ratio more will have the most effect on car handling (understeer/oversteer).
I also suspect that there is some connection between body roll angle ratio and the stock car handling.
If, maybe, the normal handling car have body roll angle ratio 3:2, then, maybe, car with body roll angle ratio 2:1 have understeer characteristic, and, maybe, car with body roll angle ratio 1:1 have oversteer characteristic.

Code: 
    car     DT   spring  height   damper    tire  f angle r angle 
 RUF BTR2   RR  0.2/0.2  250/250   10/10    N/N     6.1     7.6 
 RUF BTR2   RR   0.2/20  250/250   10/10    N/N     2.1     1.7
 RUF BTR2   RR   20/0.2  250/250   10/10    N/N     2.5     1.1
 RUF BTR2   RR   20/20   250/250   10/10    N/N     2.5     1.9
 RUF BTR2   RR  0.2/0.2  250/50    10/10    N/N     5.1     5.4
 RUF BTR2   RR  0.2/0.2  50/250    10/10    N/N     5.5     5.9
 RUF BTR2   RR  0.2/0.2   50/50    10/10    N/N     4.8     4.3
 RUF BTR2   RR  0.2/0.2  250/250   10/1     N/N     6.0     7.0
 RUF BTR2   RR  0.2/0.2  250/250   1/10     N/N     6.4     7.6
 RUF BTR2   RR  0.2/0.2  250/250    1/1     N/N     6.1     7.5
 RUF BTR2   RR  0.2/0.2  250/250   10/10    N/SS    7.0     6.4
 RUF BTR2   RR  0.2/0.2  250/250   10/10    SS/N    5.9     7.1
 RUF BTR2   RR  0.2/0.2  250/250   10/10   SS/SS    6.3     7.0

Seeing this test, using harder front spring rate should make the car understeer, but in the game harder front spring rate make the car oversteer. Maybe harder spring grip overcome weight transfer grip.
Click to expand...
This is where longitudinal location comes into play, I assume. I think this aspect has changed for GT4, though, so making rear harder on this car would make it oversteer.
 
Team666
Cool, how about FF cars, mainly under braking? The outer rear wheel should lift off, but as far as I know, it´s not doable. At least not in GT3 or 4.
Click to expand...
I am not sure it can be done in FF car, I'll try though.
Team666
This is where longitudinal location comes into play, I assume. I think this aspect has changed for GT4, though, so making rear harder on this car would make it oversteer.
Click to expand...
I see.
 
Lifting inside rear wheel can be done too, using soft front and hard rear.


This should be doable in GT4, I post the picture if I have time.
 

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