Why does increasing body rigidity lower the PP?

[Sir Crashalot]

I actually thought it would be the opposite?

 

[TumeK5]

Indeed...when I increase my PP's rigidity, it should surely be bigger. 👀

 

[AlexWilmot]

As a car turns normally the weight will shift to the outer wheel and make it turn more, making the car more rigid will have the weight more distributed across the left and right wheels more creating less roll in the turn and appear to be more "understeery" in nature in comparison, so that is why the PP is lower but when tuning the suspension and the LSD you can eliminate the understeer but the PP calculation no longer includes suspension changes

 

[Sir Crashalot]

As a car turns normally the weight will shift to the outer wheel and make it turn more, making the car more rigid will have the weight more distributed across the left and right wheels more creating less roll in the turn and appear to be more "understeery" in nature in comparison, so that is why the PP is lower but when tuning the suspension and the LSD you can eliminate the understeer but the PP calculation no longer includes suspension changes

Well, that somehow makes sense I guess.
My reasoning was that it allows the car to react quicker and more precise, maybe also enhances cornering speeds. Although I'm still not sure if this "body rigidity" in game is the same what's called "Verwindungssteiffigkeit" in German. (I think that would rather translate to "torsional stiffness", so probably is not the same.)

 

[AlexWilmot]

Well, that somehow makes sense I guess.
My reasoning was that it allows the car to react quicker and more precise, maybe also enhances cornering speeds. Although I'm still not sure if this "body rigidity" in game is the same what's called "Verwindungssteiffigkeit" in German. (I think that would rather translate to "torsional stiffness", so probably is not the same.)

It would be limiting the torsional stiffness

 

[Sir Crashalot]

OK, I'm even more confused now.

Yesterday I tuned an E-Type. Increasing Body Rigidity did lower the PP.

Today I tuned a Beat. Increasing Body Rigidity did raise the PP.

??

 

[Jump_Ace]

OK, I'm even more confused now.

Yesterday I tuned an E-Type. Increasing Body Rigidity did lower the PP.

Today I tuned a Beat. Increasing Body Rigidity did raise the PP.

??

Maybe it also depends on what other suspension items are installed? Just spit-balling here, but if you have just the stock suspension and increase the rigidity, it will improve the PP because it's improving upon the 'poor performing' stock suspension? 🤷‍♂️


Jerome

 

[MineralBlurb7]

I figured because when seam welding - which I always assumed this modification was - adds weight from the filler rod.

That’s how it works in the real world…with PD who could even guess.

 

[Sir Crashalot]

Maybe it also depends on what other suspension items are installed? Just spit-balling here, but if you have just the stock suspension and increase the rigidity, it will improve the PP because it's improving upon the 'poor performing' stock suspension? 🤷‍♂️


Jerome

Well, I don't know, that's why I asked.
I thought since this is a rather basic question and this is a subforum for tuning with ppl who tuned literally hundreds of cars, someone would know.

 

[Meythia]

OK, I'm even more confused now

??

PP calculations are both complex and buggy.
Sometimes its simply a bug, and sometimes it comes down to a very specific point of weight transfer that the game simulates in its PP calculations which isnt quite obvious for us players (or its simply bugged).
You can find cars that increase in PP with every bit of weight added, yet at some very specific individual spots of the setup it will drastically drop, or it can happen the exact opposite way.

 

[TheCracker]

I figured because when seam welding - which I always assumed this modification was - adds weight from the filler rod.

That’s how it works in the real world…with PD who could even guess.

Other than seem welding the shell, increasing body rigidity usually means adding a substantial roll cage* which strengthens and solidifies the suspension mounting points in respect to each other which gives the suspension a more stable platform to do it's job. A roll cage will add more weight, so should lower the PP.

But. Adding a cage usually means taking out a good chunk of the interior which will often cancel out the added weight of the cage, or go a long way towards it, and the added rigidity should really increase PP IMO, but you know, PD.

* i don't have GT7 so i assume adding a cage is part of the 'increase body rigidity' modification?

 

[MineralBlurb7]

Other than seem welding the shell, increasing body rigidity usually means adding a substantial roll cage* which strengthens and solidifies the suspension mounting points in respect to each other which gives the suspension a more stable platform to do it's job. A roll cage will add more weight, so should lower the PP.

But. Adding a cage usually means taking out a good chunk of the interior which will often cancel out the added weight of the cage, or go a long way towards it, and the added rigidity should really increase PP IMO, but you know, PD.

* i don't have GT7 so i assume adding a cage is part of the 'increase body rigidity' modification?

GT7 has a separate cage function.

 

[Famine]

I thought since this is a rather basic question and this is a subforum for tuning with ppl who tuned literally hundreds of cars, someone would know.

The answer is "it depends", but also "since things were taken out of the PP calculation since launch it could be bugged".

Ultimately a car that's made too stiff for its old, floppy suspension will be worse in corners and - in principle - the PP will go down with rigidity increase, whereas a car that's too floppy for its new, sparkly suspension will be better in corners with a rigidity increase and - in principle - the PP will go up.

 

[TheCracker]

GT7 has a separate cage function.

Are front and rear (if applicable) strut braces a separate function too? Not that they'd add that much weight.

As @AlexWilmot states above, stiffening the platform without altering the suspension would probably increase understeer. If a manufacturer sets up a road cars handling, its for the cars standard suspension platform. Increase the stifness between the suspension mounting points and you are making the front tires work harder when turning. A stiffer platform requires the suspension to be tuned to suit it.

 

[LeGeNd-1]

First of all, the PP calculation is not perfect. It's just a rough guide. There are lots of bugs and exploits ever since the game is released and the calculations have changed a few times since then, probably introducing even more bugs. The final result is always the laptime in your hands, not a random number PD's black box generates.

However, having tuned 300+ of the cars in the game, I've noticed a few trends:

1. The PP system gives higher numbers for straight line speed and lateral g.

2. Installing a widebody kit for example, always lowers PP. It adds drag and lowers top speed slightly. It also increases stability (wider track width) and "increases" understeer. I put quotes here because you can dial this out with suspension tuning, and around a track the advantages of widebody often outweighs the slight loss of top speed. Your end laptime is faster, but from the PP calculation POV your car is worse.

3. Increasing rigidity also increases stability/understeer. So PP system thinks your car is worse, but once you dial the suspension you can go faster around a track.

4. Increasing tyre offset in GT Auto also affects PP slightly. Changing tyre width and rim size affects handling a little, but no PP change oddly.

5. Installing rollcage in GT Auto also affects PP (and if you are a sensitive driver you can feel improved rigidity too).

6. Changing downforce is interesting. You get more grip (higher PP), but at some point if you don't have enough power you lose top speed (lower PP).

7. Sometimes just one click change in ballast or position can affect PP drastically. No one knows why but I think it's because the game drives your car on a virtual track to calculate the PP, and for some reason sometimes the AI crashes and returns a bad laptime (and a wrongly low PP).

See the part under PP where Kaz explains how it's calculated.

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[Sir Crashalot]

Yeah, I guess there's indeed something buggy here. Recently I tuned a car (I think it was the Scirocco, I'm not sure though) and instead of the usual few points body rigidity showed a plus of a few thousand points in the preview.
My goal for this car was 700PP so I did all other upgrades first to see if there are enough PP left at the end for the rigidity.
And guess what? When I increased rigidity after everything else was upgraded, the PP didn't change at all....


@Famine Could you please ask Kaz about this next time you talk to him?😉

 

[AlexWilmot]

Right so I took a Honda Beat in stock configuration, Rigidity gave a positive to the PP, so I guess the car stock is not as good due to the roll in the chassis with it's shorter wheel base.

Now since the PP system has been "nerfed" to not have suspension changes affect it, Aero still does so I added aero to it and in base settings the Rigidity decreases the PP, now the stock aero is set to 10 front and 100 rear, this is making the rear grip more than the front I believe the rigidity is enhancing this setting.

Next I changed the Aero to full front and min rear(what I believe to be the best settings due to the front having grip and the rear not gripping too much in high speed corners) and the rigidity did nothing, I think this is due to the aero having such an advantage that the rigidity doesn't matter.

Then I gave it full aero around and the rigidity came as negative on the PP similar to the second point.

Basically, I think the other settings, wheelbase, age of car etc have more of an impact on whether the Rigidity is valuable or not to a car's performance and hence why the PP changes

 

[bread82]

Yeah, it definitely depends on other settings. I had a stock car which had no PP effect from rigidity when you checked it out in the tuning menu.

As I added weight reduction stages, the PP from the rigidity became positive. Probably just the vagaries of the PP system.

The chassis flex should act like more springs on top of the actual suspension, which will slightly soften it overall (the chassis is far stiffer than springs, but ANY additional spring rate will soften things overall). Rigidity should reduce this additional spring.

I often wonder what the lap time cumulative effect of all the small PP parts is. Rigidity, widened and offset tyres, roll cage, flywheels and prop shaft...

 

[Meythia]

I often wonder what the lap time cumulative effect of all the small PP parts is. Rigidity, widened and offset tyres, roll cage, flywheels and prop shaft...

At least for wide tyres they improve tyre life.
SSRX, fuel x3 tyres x50
normal car:

wide tyres:

It is not by much, but it will accumulate over the laps obviously.
Normal Wide Normal Wide
Left Left Right Right

 

[bread82]

That is cool, and I seriously suspect you were the only person in the community that knew about it, many thanks for sharing.