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Eric Everfast
23-08-2017, 16:11
Hi all,

I felt like it would be a good idea to have a dedicated space on here to talk about tuning. The main purpose of this thread is to shed some new light on what can often be a daunting endeavour for newcomers such as myself. I would like to get some engaging discussions out of this as much for myself as for others interested in this area of motorsport. Conversation starters can include:

- Bringing up a circuit or a specific set of turns in a circuit and asking how to optimise the suspension, brake bias, gear ratios, etc.

- Asking more general questions on how an aspect of tuning affects vehicle dynamics (roll couple distribution, camber/toe changes, etc.)

- Suggesting a book/article pertaining to the topic that you thought was a good read

the list can go on.

I am not quite sure if this will turn out to be the best place to have a thread like this but I am willing to give it a shot. Of course, the game is not out yet so setups can't be shared; however more general order discussions can take place from now until release.

Eric Everfast
23-08-2017, 16:24
I'll start things off:

I want to talk about handling balance in uphill/downhill corners; more specifically increasing/decreasing spring and anti-roll bar rates.

If we were to take the first turn at COTA as an example (uphill for those who don't know), how would you go about adjusting the anti-roll bars and springs? From my readings, stiffening anti-roll bars and the springs in front would cause more understeer and doing so in the back would obviously cause more oversteer. It follows that if the vehicle is still on an incline after braking (just before turn in), the weight would shift back to the rear more quickly.

How would you go about setting this up?

honespc
23-08-2017, 18:00
a) Front engine cars: You want stiffer springs and rollbars in the front, and softer, usually a lot softer in the rear.
b) Mid Engine cars: Try go set the rear and the front as evenly as possible, both springs and roll bars.
c) Rear engine cars: Rear springs stiffer than the front but not too much. Roll bars stiffer on the front. Lower rear height.
d) Open Wheels: Depends on the car.

Eric Everfast
23-08-2017, 18:18
a) Front engine cars: You want stiffer springs and rollbars in the front, and softer, usually a lot softer in the rear.
b) Mid Engine cars: Try go set the rear and the front as evenly as possible, both springs and roll bars.
c) Rear engine cars: Rear springs stiffer than the front but not too much. Roll bars stiffer on the front. Lower rear height.
d) Open Wheels: Depends on the car.

Thanks for the reply.

Interesting distinction between your a) and c) points... all other parameters being equal I'm guessing. Is this because of the drive train (assuming your points are all for RWD)?

ramm21
23-08-2017, 18:30
Thanks for the reply.

Interesting distinction between your a) and c) points... all other parameters being equal I'm guessing. Is this because of the drive train (assuming your points are all for RWD)?

You basically want stiffer springs on the end with more weight.

honespc
23-08-2017, 18:43
Interesting distinction between your a) and c) points... all other parameters being equal I'm guessing. Is this because of the drive train (assuming your points are all for RWD)?It is because of the engine position. You need the zone where the engine is placed at to not oscilate hard. That's why you mean to go stiffer on those zones.

Then you have the dumper thingies..., I'd suggest to always go softer on the rear regardless the engine position, with the exception of 4x4 cars.

More rear negative camber on rear engine cars is a good thing, just as It is on 4x4 cars too.

Then you have the differentials..., a whole world too in what it comes to change your car as it takes corners. Higher/stronger acceleration diffs are preferred for power-sliding on tarmac (not on gravel); (the car suffers more to turn, but in exchange you can mess harder on the throttle to make the car turn without risk). If you want your car to turn better then run a more open acceleration diff (slide to the left). However, if the car has a lot of HP you will spin out more easily, specially if you deceleration diff % is low as well.

And on the deceleration diff..., if you have some really good braking skills (you tend to bias it a bit to the rear wheels instead to the front, and brake sightly as you take turns in combination with the throttle), then tone it down. This is great for road cars for a mixed use of brakes and throttle at once when cornering in combination with a strong accel diff, which leads to glorious drifting fun, and the always sweet smell of burnt rubber.

If on the other hand you are one of those that jam the brakes in the last moment, then you may want a higher/stronger decel diff configuration, usually above 55% depending on the car and class. This is kinda the way to go with race cars, and open wheels too.

Eric Everfast
23-08-2017, 18:43
You basically want stiffer springs on the end with more weight.

Makes sense. How about the stiffer anti-roll bars coupled with the stiffer springs in the front for a front engine car vs. stiffer anti-roll bars in the front and stiffer springs in the rear for a rear engine car? That's the glaring difference I see in what was mentioned above.

I could see how it would work, given that you want to reduce as much rolling as possible in the back with stiffer springs all while off setting oversteer as much as possible with stiffer anti-roll bars in the front. But then how do you explain the vehicle dynamics for the front engine car with that extra rigidity in the front causing understeer?

Please correct if I'm wrong in any of the points that I am bringing

honespc
23-08-2017, 18:49
Stiff rear roll bars usually isn't a good idea regardless the engine emplacement. I'd go stiffer front roll bar, always. Even on open wheels.

Roll bars are auxiliary "systems". Don't look into them too much, but also don't mess with them too hard, specially with the rear roll bars. They won't let the springs work at full efficiency if set too stiff

ramm21
23-08-2017, 19:04
My theory on tuning-
Essentially all cars are set with soft suspensions and high ride heights. This is because the base tune should be drivable on circuits like Zhuhai and Oulton Park, which have very different "terrain." A soft setup works for both, although better set up for Oulton than for Zhuhai. A stiff set up would work well on Zhuhai, but awful for a bumpy track like Oulton Park. So the cars are set up more for the rougher tracks.

The most bang for the buck in tuning for a particular track will come from ride height, camber, springs and roll bar adjustments. Honestly, just dropping the ride height should give better performance since you minimize drag on straights and set a lower center of gravity for cornering.

My plan is to figure out ride height and spring stiffness first. Adjust camber for optimal steady state cornering, then roll bars to get a base tune for a particular track. From there I will use other parameters to fine tune further, like tire pressures and diff adjustments.

I think aero is another important element to a base tune, but thats really car dependent. High power high downforce cars I would lump aero into the first few adjustments I would make, but just to get a rough idea (for example if you know the track is low-downforce like Monza, set downforce to minimal at the beginning and work your way up once you get into fine tuning).

What do you guys think? PC2 will be the first time I'll dive into setups, I've been playing with stockers all this time so I'm not really speaking from any experience right now, but I've been reading up on tuning, gearing up for release

honespc
23-08-2017, 19:44
In my opinion tyre pressure is the most important tweak of all. Knowing that you must run high pressures on road tyres if you don't want to begin losing grip around by your next hardcore drifting loop, relatively low on semi-slicks and very low on racing slicks to get the most out of them is something crucial to ensure the perfect behaviour of the car, either road or race type, and not begin losing grip by the third or four lap.

One of the downside aspects to the tyre model in project cars was that devs didn't seem to give hot tyre pressures the importance they deserve, to the point that it should have been the main following indicators you should have to use in order to know what pressures for each tyre compound are requiered, as well as help in running asymmetric pressure setups suited to each of the tracks.

Assetto Corsa does good in this area for instance, marking you what cold pressures you must use for each tyre compound and track once you have done four laps or so, and see if those hot tyre pressure numbers stay neither in the blue or the red colour, but on the green. If the psi numbers stay on the green after a number of laps, then your cold pressures were right.

Here's hoping tyre model in project cars 2 isn't about only marking temps based on lower or higher cold intial pressures. That is just wrong, and imo where assetto corsa always terrible tyre model has beaten project cars model. Let's be honest here.

Then It comes the ride height, springs, downforce, etc, but first the tyres in importance in my opinion.

Mattze
23-08-2017, 20:37
Will there be a visual support to adjust the correct ride height in senseful manner? A tool that indicates whether your car has bottomed out would be amazing.

hkraft300
24-08-2017, 08:49
What you guys are referring to as spring rates are actually wheel rates. You're not taking into consideration motion ratios.
Example: Audi R8 GT3 has much higher front motion ratio than rear. This is due to the suspension design, arm lengths and what not for optimal packaging/ kinematics.
If you put higher rear spring rates than front on the R8 GT3, the car ends up with super stiff rear and you get silly oversteer.

The wheel rate/ frequency determines grip, and the F:R frequency bias will determine steady state handling balance, depending on your tyre sizes.


http://youtu.be/hGZRairqHNI

I urge you to check out jussi's suspension calculator at projectcarssetups.eu. have a play with different spring rates. Take a car you're familiar with. Set your front frequency higher by 20%, do some laps. Try higher rear frequency by 20%, do some laps to compare.

hkraft300
24-08-2017, 10:04
Will there be a visual support to adjust the correct ride height in senseful manner?

That's called the telemetry screen. You can see where/if your height gets too low. It's hard for some to drive and keep 1 eye on the suspension numbers. There are apps like MikeyTT's vrHive that have complete data logging.
You can also hear when the car scrapes.

honespc
24-08-2017, 11:10
"The purpose of springs is to keep tyres on the ground"

And what about bodywork oscillation. Isn't that a purpose to suspension too?, or do they leave that to anti-roll bars only?. The only reason for preferred softer springs over stiffer is that no track is 100% smooth. All of them are bumpy to some extent, and others are straight away bumpy from beginning to end.

hkraft300
24-08-2017, 14:23
"The purpose of springs is to keep tyres on the ground"

And what about bodywork oscillation. Isn't that a purpose to suspension too?, or do they leave that to anti-roll bars only?.

Yes.
Springs are your primary tool to control body motion. Where you have fast transitions or chicanes, you have to compromise and increase your spring rate to limit the body roll.

As for oscillation, damping is extremely important. Too little damping: the car is still oscillating when it hits the next bump in the road and unloads the tyre therefore losing grip. Too much damping is similar to stiff springs. It stops the springs from doing their job, which is to control wheel and body motion.

Roll bars are minor tools for controlling body motion. I use roll bars for fine tuning the handling balance.

Eric Everfast
24-08-2017, 15:38
Stiff rear roll bars usually isn't a good idea regardless the engine emplacement. I'd go stiffer front roll bar, always. Even on open wheels.

Roll bars are auxiliary "systems". Don't look into them too much, but also don't mess with them too hard, specially with the rear roll bars. They won't let the springs work at full efficiency if set too stiff

I'll keep this in mind. Though I can't help but think that stiffening the rear anti-roll bar would be the intuitive thing to do in some cases (when a car has prominent understeer). I guess this will apply more to the road cars in the game with most of the race cars not having that problem in stock form.

A good example is provided in the book I'm reading: High Performance Handling for Street or Track by Don Alexander (maybe some of you have read this). In the early 90s, he was asked to improve the suspension setup for a Shelby CSX in the IMSA sedan series that was being outperformed by most of the cars in the class. Among other adjustments, he did end up stiffening the rear anti-roll bar by "a notch" as he says in the book. It was one of the changes that allowed them to get a 1.07g cornering force and most importantly, get the car in the top 5 regularly.

Granted this is an old road car that was used for racing so it comes back to my original point.

Eric Everfast
24-08-2017, 15:52
One of the downside aspects to the tyre model in project cars was that devs didn't seem to give hot tyre pressures the importance they deserve, to the point that it should have been the main following indicators you should have to use in order to know what pressures for each tyre compound are requiered, as well as help in running asymmetric pressure setups suited to each of the tracks.

This is something I remember being mentioned by the announcers of IMSA not too long ago during the Lime Rock park race. That track is the perfect example for asymmetric tire pressure given that it's all right turns bar turn 3. I'll definitely be reading more into that. I'm interested in knowing how it might affect straight line speed and braking performance.

Eric Everfast
24-08-2017, 15:53
What you guys are referring to as spring rates are actually wheel rates. You're not taking into consideration motion ratios.
Example: Audi R8 GT3 has much higher front motion ratio than rear. This is due to the suspension design, arm lengths and what not for optimal packaging/ kinematics.
If you put higher rear spring rates than front on the R8 GT3, the car ends up with super stiff rear and you get silly oversteer.

The wheel rate/ frequency determines grip, and the F:R frequency bias will determine steady state handling balance, depending on your tyre sizes.


http://youtu.be/hGZRairqHNI

I urge you to check out jussi's suspension calculator at projectcarssetups.eu. have a play with different spring rates. Take a car you're familiar with. Set your front frequency higher by 20%, do some laps. Try higher rear frequency by 20%, do some laps to compare.

One of the best channels on youtube.

hkraft300
24-08-2017, 16:40
... stiffening the rear anti-roll bar would be the intuitive thing to do in some cases (when a car has prominent understeer).

Maybe because the front frequency is too high. You'd reduce front spring rates first, before increasing rear sway bar.
Increase sway bar/ spring rate effectively reduces grip on that axle. So in an understeer car, you want to add grip to the front before you remove grip at the rear. In an oversteer car, add grip to the rear.


One of the best channels on youtube.

Sure is.

More relevant to racing:

http://youtu.be/d0voTx7AuZQ

honespc
24-08-2017, 20:10
This is something I remember being mentioned by the announcers of IMSA not too long ago during the Lime Rock park race. That track is the perfect example for asymmetric tire pressure given that it's all right turns bar turn 3. I'll definitely be reading more into that. I'm interested in knowing how it might affect straight line speed and braking performance.Precisely, asymmetric cold tyre pressure is done for when the tyres reaches optimal hot pressure, they end up being evenly (symmetric) on each train. It's when running the same pressure on the left and right tyres that you will end up having uneven pressures once they reach the optimal hot pressure mark.

This means that running the proper asymmetric tyre pressure suited for each track grants better straight stability, not the other way around.

It's just too bad devs didn't focus on hot tyre pressures and their importance in order to let us know what the optimla cold pressures should be for each tyre compund, and track. The have focused only on temps, and I fear the story will repeat in pc2.

The best thing of Assetto Corsa tyre model lies precisely in the seek of the perfect cold tyre pressures, thanks to number indicators per tyre we have available as we drive (the inner tyre presure mark, that will mark us the ending hot pressure). It's indeed the best aspect of their model. In project cars, hot pressure doesn't matter just one bit regardless they end up being higher or lower, and tyre compound too, and that makes assettos tyre model superior in this area, which is one of the most important ones btw.

hkraft300
24-08-2017, 23:32
PV = mRT

In a tyre, the volume is fixed (tyre stretch can be considered negligible), and being enclosed, the tyre contains the same mass of air.

So the ratio P(cold)/T(cold) = P(hot)/T(hot).
However: the T is the air temp inside the tyre. What we see in game are core layer tyre temp. Not surface or air inside the tyre.
Hence the discrepancy.


Precisely, asymmetric cold tyre pressure is done for when the tyres reaches optimal hot pressure, they end up being evenly (symmetric) on each train. It's when running the same pressure on the left and right tyres that you will end up having uneven pressures once they reach the optimal hot pressure mark.

At a track like lime rock symmetric pressure would not be optimal. In pc1, even tracks like Brands GP or Road America with heavy FL wear and a temp difference of 15-20c, the pressure variation isn't so big to cause instability.
Say you try to reach equal hot pressure, but the increased FL load and temp is making your pressure high. If you reduce the cold pressure, the tyre flexes more and heats up so your hot pressure gets higher anyway.
Then your grip suffers and you push a bit harder creating more heat and pressure that spirals out to a no grip and tyre life.
So, sometimes a little higher cold pressure may be necessary. But before you start asymmetric pressure, you should have your mechanical (suspension) and aerodynamic balance sorted.



It's just too bad devs didn't focus on hot tyre pressures and their importance in order to let us know what the optimla cold pressures should be for each tyre compund, and track.

See above. What is the optimal cold tyre pressure?
Are the track and ambient temperature same at all tracks?
Are the tyre loads experienced by a 12C = Bentley?
Are each player driving style the same?
Because they're all closely related.
My cold pressure will be different than yours. My tunes are different. We drive different. We all load the tyres differently. You may be driving faster in a qualifying run that loads the tyres more, giving it more energy, therefore high temp and pressure.


In project cars, hot pressure doesn't matter just one bit regardless they end up being higher or lower, and tyre compound too, and that makes assettos tyre model superior in this area, which is one of the most important ones btw.

Really? Because it seems to matter a lot in project cars.
If my cold pressure is too high, the tyre doesn't flex enough, so it doesn't heat up enough to give me good grip. If my cold pressure is too low, the tyre flexes too much when it loads/unloads and creates it's own heat. That makes the compound too hot, reaching high hot pressure, and you lose grip.
When you have optimal pressure, the tyre isn't too hot or too cold, giving you optimal grip.

So yes, pressure and temperature are very closely related.
Devs did fail to give an optimal temperature range for the tyre compounds, but that can be easily found by testing.

honespc
25-08-2017, 12:41
Devs did fail to give an optimal temperature range for the tyre compounds, but that can be easily found by testing.But that's precisely the point. In project cars you have the tyre temp as the indicator to follow, but It shouldn't be like that. The marker to follow should be the correct hot tyre pressure range you find after doing a number of laps, not the temperatures you get. From there, if you get higher temps is because you're pushing hard and need to calm down for a lap or so, and if low then you need to do the opposite thing, but the tyres stay on their optimal hot pressure spot, and they don't give you "surprises" or unexpected behaviour. This can't be known in Project Cars.

This being said, and when you are let's say on your fifth lap, and already reached the required hot pressure depending on your tyre and track temperature (the factors to have into account when choosing cold pressures, but that's what practice sessions are for), then It doesn't matter that the temps are higher or lower. What It matters is to reach and stay on the optimum hot tyre pressure spot, and from there, applies the aforementioned in the previous paragraph.

That is the point, and what Assetto Corsa does right and what pc doesn't. In assetto you begin by taking into account the tyre compound and track temp. From there, you must do in each steam at the very least six laps. If the hot pressure numbers stay more or less on the green, then you are good to go with those pressures regardless you overheated this tyre or the other. In project cars this doesn matter. You mount your tyres, they enter the green temperature zone by the second or third lap, and then that is all. Did you go a little low on cold pressure?. No problem. You just lose a bit of speed and your temps go a little high after the third lap, or lower depending on other factors such as tyre type. Did you go a little high on cold pressure?. No problemo. You will lose some grip on cornering but gain little extra speed on straights, as well as higher or lower tyre temp depending on some factors. This isn't right.

On the other hand, if in assetto you end up on either blue or red hot pressure numbers by your third or fourth lap regardless the tyre temps you are getting, then you will notice instantly that something is not right. You lose grip and unexpected behaviour begins showing in every corner you take. Why?, because you are not running those tyres you are currently equipping on their optimal hot pressure range. The range they are made to run optimally on, regardless a higher or lower core/carcass temperature.

Another example, and by the way the hard one and where you realize assetto does things right on this area. In Assetto Corsa, specially on semi-slick tyres, you have to push them hard to reach the optimal temp, and you usually end up racing with them semi-cold (semi-blu colour to green if you don't push). However, if you are running on them with the hot tyre pressure numbers on green, then they behave reasonably well regardless their temps stay a little blue (light cold), or a little hot (bordering on the red). Same for the GT3 slicks and such. They can go red in the temps, but if the hot pressure markers stay on the green, then that's how it is. In project Cars we don't see anything like this, to the point that:


Really? Because it seems to matter a lot in project cars.That's what I first though and even open a topic around on the subject. However, after way more intensive testing on seeing if hor pressure ranges had a meaning/importance in project cars tyre model, I ended up realizing that It simply doesn't. Hot pressure optimal range (which you can not know in project cars what range is that, another problem btw) in project cars has no bearing at all.


What is the optimal cold tyre pressure?It's left unclear in project cars model, and hence the optimal hot pressure.


Are the track and ambient temperature same at all tracks?Of course they aren't, but that doesn't help in project cars as well. In assetto corsa these factors only add more to the fun of finding the correct cold pressure spot per track and per weather condition. Even more fun this assetto system allow you to find a nice proper asymmetrical tyre pressure. In project cars it simply does not matter at all.


Are the tyre loads experienced by a 12C = Bentley?That is a good example, but the optimal pressure range stay the same as they use the same tyres. On the Bentley you just gotta apply extra 0'10 bar on each train compared to the 12c just due to aerodinamic , behaviour and extreme horsepower reasons rather than the weight oriented ones. Even then, in Project Cars, you can run same pressure in the Bentley and the 12c and the difference will go unnoticed. The special car on this area is the Audi R8 GTLM. It's here that you need a really lower cold pressure. Why?. I honestly don't know, but probably because it's a particularity in project cars, and that would be just about all.


Are each player driving style the same?Hot pressure marks applies to everybody in the same sense if using same tyre compound. As said in one of the first paragraphs, If you run hot in some of your tyres even if you are on the sweet hot pressure spot, that doesn't mean you have to find another cold pressure to run with. What you have to do is to slow down a little until it cools down. If the opposite happened, then push. Asetto does wonders on this system. Project Cars simply doesn't, because it doesn't seem to be even present.


Because they're all closely related.
My cold pressure will be different than yours. My tunes are different. We drive different. We all load the tyres differently. You may be driving faster in a qualifying run that loads the tyres more, giving it more energy, therefore high temp and pressure.This is what you find out when toying around with cold pressures in assetto corsa. Our driving styles and tunes might be different, but our tyre cold pressures on the same type of tyre compound should be almost the same, if not the same. I'd take my chances and even dare say you and me (or any other) would end up having similar if not the same asymmetrical cold tyre pressures in assetto corsa on the same tyre compounds and track temps. In project cars we can't simply know. Why?, because it's just temp based, and even then it doesn't seem to matter at all too.

Sorry for wall of text.

hkraft300
27-08-2017, 01:12
But that's precisely the point. In project cars you have the tyre temp as the indicator to follow, but It shouldn't be like that. The marker to follow should be the correct hot tyre pressure range you find after doing a number of laps, not the temperatures you get.
...
That is the point, and what Assetto Corsa does right and what pc doesn't..

Tyre surface doesn't find grip from pressure. If it was the "hot pressure" that gives grip, then any tyre at 50℃ would give it's maximum grip at its optimal pressure.
Tyres have to be hot enough so the tread surface rubber becomes soft and flexible. This allows it to deform and fill in to the rough asphalt road surface to give you grip.
You can follow tyre pressure range if you like in pc1 that's entirely up to you. The information is there.
GT and LMP tyres reach good grip at ~100℃ and ~2.0 bar pressure.

I haven't played AC. I'm not getting in to the AC vs PC debate.

hkraft300
30-08-2017, 00:46
If we were to take the first turn at COTA as an example (uphill for those who don't know), how would you go about adjusting the anti-roll bars and springs? ...
How would you go about setting this up?

Depends what the car is doing at that corner. Analyse the root cause of the problem, take all the symptoms in to consideration, act accordingly.


http://youtu.be/MfPgKnxJJ6I

Is the car driving nicely on every other corner?
Should you compromise every other corner for one?
Can you drive around the problem?

If it ain't broke, don't fix it.