Finding Exact CoM

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GhostZ

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The__Ghost__Z
Does anyone know how to find the exact location of a car's center of mass? It gives you the location Front-to-Back in the Ballast screen, but does not tell you how far from the ground it is. I've been assuming that it is halfway down from the roof of the car, but this is probably not generous enough for some vehicles. It doesn't really affect optimizing for weight transfer, but it does give me more precise measurements to compare cars performance in relation to their CoM location.
 
The only thing you are able to find is the weight distribution per axle. It is impossible to find or calculate with the info that GT5 gives you. You may be able to Google it and guesstimate where it might be as you make changes but I'm not sure how it would help you within the context of GT5.
 
Under stock form it could be possible to google, but with weight reduction mods, its unknown exactly *where* that weight is removed from.

I figure that someone might know how PD calculated CoM for cars, since I'm sure they have to for the game to work properly, and whether or not all standard cars had some blanket height given to it at stock as a percentage of its total height, and then perhaps reduced by a certain amount with each weight reduction. That, and the game (annoyingly) doesn't give you exact wheel size measurements as far as I can see.

Also, another question while I'm here, how can we figure out downforce at a given speed? If the rear downforce setting is, say, 30, does that mean 30 kg at 100km/h or something? Or is that another unknown?

EDIT: I figured out a way to calculate CoM using the information off the game, nevermind my initial question.
 
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Oh? I'd be interested in how you managed. I would think, as you alluded to, that finding the center for yaw and roll (I pretty much assume dead center for this anyway, given the tuning options and settings) would be easy enough but the pitch axis...I just don't see how that could come from anything GT5 offers.
 
In GT5 I do believe all weight reduction leaves every car in exactly the same proportions as before the weight reduction.
 
yes, CSL is right. stripping weight removes weight proportionally from entire car maintaining weight distribution. putting it back on with ballast does not obviously even with ballast in the middle.
 
esoxhntr
yes, CSL is right. stripping weight removes weight proportionally from entire car maintaining weight distribution. putting it back on with ballast does not obviously even with ballast in the middle.
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On 50/50 cars I believe it does.
On something, say, 40/60, you'd have to put the ballast at 10, or for 60/40 ballast at -10.

Not sure though, I haven't tried cars with/without ballast at the same spec against each other. I almost feel like adding ballast is slower than not doing the weight reduction.(assuming same weight of course)
 
MSTER232
:eek: how did you find out?
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I'm more surprised you believe that he has and is correct.:eek:
I'm not even sure CoM is in the game. CoG, definitely, CoM? MMaybe, I'd need proof to believe it. I've seen way to much simplicity in GT5's coding/programming to believe it without seeing it.
 
CSLACR
On 50/50 cars I believe it does.
On something, say, 40/60, you'd have to put the ballast at 10, or for 60/40 ballast at -10.

Not sure though, I haven't tried cars with/without ballast at the same spec against each other. I almost feel like adding ballast is slower than not doing the weight reduction.(assuming same weight of course)
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I think we're saying the same thing

on a 60/40 1000kg car, (600kg front, 400kg rear) if you remove 200kg, 120 will come off the front and 80 will come off the rear resulting in a 800kg car with 480 f/320 r.

if you add the 200kg back in via ballast at 0.. you're adding 100 and 100 front/rear. resulting in a car that weighs 1000kg again but 580 kg f & 420 r.. and weight distribution becomes 58/42.

the spec is the same.. i suspect the PP will not since distribution plays a [small] factor in that calculation.
 
esoxhntr
I think we're saying the same thing

on a 60/40 1000kg car, (600kg front, 400kg rear) if you remove 200kg, 120 will come off the front and 80 will come off the rear resulting in a 800kg car with 480 f/320 r.

if you add the 200kg back in via ballast at 0.. you're adding 100 and 100 front/rear. resulting in a car that weighs 1000kg again but 580 kg f & 420 r.. and weight distribution becomes 58/42.

the spec is the same.. i suspect the PP will not since distribution plays a [small] factor in that calculation.
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Then yes, we are agreed.
PP will only change slightly from moving the weight forward and backwards, and sometimes it won't show from doing a test exactly like that. It has to fit the required range to change the PP, sometimes it's enough, others you might have to move the ballast further to see the PP change, and occasionally, depending on exact specs, the PP won't change at all.(Typically if it's a low amount of ballast or heavy car)

I forgot to mention that the game does seem to recognize that FWD benefits from weight on the front instead of the rear. At least on all the FWD's I've checked to date.
 
CSLACR
I forgot to mention that the game does seem to recognize that FWD benefits from weight on the front instead of the rear. At least on all the FWD's I've checked to date.
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LOL it's possible but I wouldn't know -- don't bother with wrong wheel drive vehicles. Still, I can't see any benefit of adding MORE weight to the front on a vehicle that's already nose heavy.. with maybe (?) the exception of drag racing?
 
esoxhntr
LOL it's possible but I wouldn't know -- don't bother with wrong wheel drive vehicles. Still, I can't see any benefit of adding MORE weight to the front on a vehicle that's already nose heavy.. with maybe (?) the exception of drag racing?
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Well, 50/50 FWD's don't exist that I'm aware of, so I would have to assume throwing ballast on the rear to make a FWD 50/50 isn't the fastest way to go?

I don't know exactly why, but then I find it more ridiculous that adding it to the rear of a 38/62 car adds PP.
As far as I've always been aware, 50/50 is perfect. GT5 feels differently.:crazy:
 
Yeah. For whatever reason, GT5 likes to think that adding more weight onto the drive wheels is always better; and because of that weight distribution simply doesn't apply to AWD vehicles (though there are ones where shifting weight around ups the PP a grand total of one point, the amount can be counted on your hands and you have to make absolutely massive changes to get them to register at all).
 
CSLACR
Well, 50/50 FWD's don't exist that I'm aware of, so I would have to assume throwing ballast on the rear to make a FWD 50/50 isn't the fastest way to go?

I don't know exactly why, but then I find it more ridiculous that adding it to the rear of a 38/62 car adds PP.
As far as I've always been aware, 50/50 is perfect. GT5 feels differently.:crazy:
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Putting weight on the rear of a FWD should reduce that drivetrains tendency to understeer being so nose heavy and balance the whole thing out a little better. But if what Toronado says is true, that question is answered.

I guess that and your 2nd point are just more prime examples of GT5isms.

As far as 'perfect' distribution goes, I think it is debatable but I've always been under the impression that a slight rear bias was most desirable. ie 45/55 or so.
 
Toronado
Yeah. For whatever reason, GT5 likes to think that adding more weight onto the drive wheels is always better; and because of that weight distribution simply doesn't apply to AWD vehicles (though there are ones where shifting weight around ups the PP a grand total of one point, the amount can be counted on your hands and you have to make absolutely massive changes to get them to register at all).
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Interesting, I haven't done much with 4WD's (Worse than wrong wheel drive if you ask me) so it's good to know. :)

esoxhntr
Putting weight on the rear of a FWD should reduce that drivetrains tendency to understeer being so nose heavy and balance the whole thing out a little better. But if what Toronado says is true, that question is answered.

I guess that and your 2nd point are just more prime examples of GT5isms.

As far as 'perfect' distribution goes, I think it is debatable but I've always been under the impression that a slight rear bias was most desirable. ie 45/55 or so.
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I guess I'd have to wonder why the highest performance cars get as close to 50/50 as possible then.
And of course 45/55 would be terrible for FWD. I really don't know for certain what's "optimal" over the course of a track, and it probably changes track to track, but generally I believe 50/50 is perfect for cornering by itself, yes. Equal weight/stress to all 4 tires will certainly maximize available grip. Typically 45/55 or further biased cars need staggered tires.
IMO, staggered tires = Rubber missing from the smaller tires. Reducing front grip to stabilize the car, instead of using all possible grip available. I could be wrong too.

Putting weight on the rear does make the FF's corner better, but you have less grip exiting corners. FWD's biggest struggle is exiting corners, so there is some logic to it.
Corner entry and mid-corner speed are great, but nothing is more important than good cornering exit ability.

But no, I won't be adding weight to the front of a FWD in real life anytime soon. :lol:
 
CSLACR
I guess I'd have to wonder why the highest performance cars get as close to 50/50 as possible then.
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I'm clouding real world with GT5, my apologies. :D MR (thus rear biased) drivetrains are usually quickest in circuit racing.

But even in GT5 the quickest cars are rear biased (I think)? ie. Elise
 

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