Need help tuning Rear Engine cars for online mode

[panjandrum]

One of the problems some of us are running into is that online handling is different than offline handling. The effect seems to vary considerably from car to car and track to track, and often isn't a terribly big deal. However, in the case of most of the RR cars what we are seeing is that online these cars respond almost nothing like real-life rear engined cars. There are a number of significant problems that I was hoping someone here might be able to help with. (I'm one of those people who almost always drives his cars with stock suspensions, so my tuning skill in GT5 are adequate, but nothing to write home about.)

So if any of you tuning wizards want to tackle the online handling of these cars... (I would start with the Alpine 1600s, the Yellowbird, and the RUF BTR)>

1) These cars should turn-in aggressively off-throttle, but when you squeeze the throttle back down they should "settle" that heavy butt back down. (RR cars, as a general rule will understeer on throttle, and then oversteer when you let off and then settle back down when you get back on-throttle again). Doing this properly and in a controlled manner is the key to taking advantage of a handling advantage these have over most other cars. It is critical that this be simulated properly. In stock form this does not work online in GT5).

2) These cars should not catastrophically snap-back when you get even the tiniest amount of lift-off oversteer. You must often (depends on the corner) allow these cars to gently and controllably rotate in order the get maximum performance out of them. In GT5 online this is nearly impossible. Even the tiniest most minuscule amount of off-throttle oversteer results in snap snap snap snapback.

I've wasted hours trying to fix these things for online racing. I can fairly easily get the cars to behave a bit better (just giving them absurd amounts of rear toe-in can help a lot), but I've been unable to do so in a way which does not hamper the proper handling dynamics of the car (I can't make them become stable on-throttle without also making them unwilling to rotate off-throttle. Bad...). I've also be completely unable to do anything with the Snapback, even on Sports Hard tires.

Here is the original thread in case some of you haven't run across it. I don't want to start another discussion about it here in this thread. I'm hoping this can be only for potential solutions.

Here is a movie I put together of the problem itself. The linked video is some offline footage and some online footage. Generally, the offline footage shows the car responding properly to inputs. It all happens a bit too easily, but the car feels right and responds to real-world driving techniques properly for an RR car. The second half of the video is online footage. It's, um, amusing (let's just say, it isn't a minor handling difference, it's full-on Jekyll and Hyde...)

Offline and Online handling of the Alpine 1600s

Note: the amount of lift-off oversteer I'm using in that video is purposefully exaggerated for demonstration purposes. When talking about doing it for speed you should do it significantly less in most situations. However, when online, essentially zero lift-off oversteer is allowed without massive repercussions.

The problem is so severe that the Yellowbird can't even maintain stability in what is basically a steady-state sweeper:

Stock Yellowbird Steady State Sweeper issue in online mode

I would be very grateful for any assistance some of you tuning experts could lend in making these cars handle properly online. (I suppose in the ideal world, a tune would simply make the online handling of these cars feel as similar as possible to the way they handle offline on stock suspensions. But I expect that's not going to be possible.)

I'm using a FFB wheel. Fanatec GT3 RS v2

 

[Qxs-Storm]

I have only done testing online @ Nurburgring, with a handful of cars.
Try (racing soft, no aids, abs=1):
1. drop the nose and raise the rear height, about a difference of 10-20 mm.
2. reduce the rear spring by 3 or 4, may also have to drop the rear compression, extension, and up the rear roll bar (afaik these are all related to each other). -this should let the weight sit down on the back tires when accelerating, afaik.
3. shouldn't need a lot of toe out on the front to get better turning, I haven't tried extreme values with this setting.
4. camber on Nurb can be handy, 2-6.. but may be lower elsewhere...
5. braking, try high front - low rear, if that is bad then reverse it... ex: 8/4 or 4/8

I haven't tried anything really old or really slow... as I have no interest in going slow
I do have a newly acquired RUF Yellowbird, I'll see about giving it a whirl.
PS I'm no expert so, my apologies if I steer you wrong. :/

 

[Stiggles]

I've been playing around with the the Rufs to try and get them stable and have a basic tune which I have modified from Porsche's real life specs. Using it I've been able to make competent tunes for RR drive cars. The basic principles of the tune are:
-Front Springs around 60% the rate of the Rear Springs (I've found the stock rear rate is pretty good most times, it's the front rate which should be lowered, the rear might need to be lowered in especially twitchy cars).
-Rear Dampers stiffened slightly to account for front spring softness
-Front and rear dropped slightly with the front being roughly 10mm lower than rear.
-Rear Anti-Roll bars are quite stiff, with Front bars being 2-3 notches lower. (On especially twitchy cars, this is inversed)
- Camber in front is around half the value of the rear (neither value being more than 3 degrees, which is only to limit tire use on edurance races, on shorter races higher values could help).
- both front and rear have very slight toe in with the rear having ~4x the front (something like 0.02 and 0.09)
-Front and Rear Brakes: 3 and 2 respectively. This value should balance out the brakes while still allowing a little trail braking.

Following these guidelines I have smartened most of the RR Rufs, though the Yellow Bird and BTR are still a little... unique. If you use them you should be in the ballpark of a good setup which still retains the personality of the car you started with (at least it works with the Porsches). Tweaking is still necessary, and may result in a tune wildly different from what I've decribed up above. On the BTR I had to go a bit drastic with the spring rates and camber to stop it from spinning out so often, and even now it's still not what I'd call an easy car to drive fast. I tend to tune conservatively in regards to alignment settings, so if certain things seem a little too slick, some added camber or toe could help out in shorter races.

If you want the exact setup PM me and I'll Email you the excel file I have with the RUF setups in it. And if you want I can try out some tunes on the Alpine to find something more reasonable than the stock settings.

BTW: Online physics are not different, but the tires do act differently. Offline tires don't lose tread nor do they really ever cool off like they do online. I have been able to get online times within 0.2 of my best offline times in the first few laps after warming up the tires on the outlap. Tires online have a very narrow timeframe where they produce their best grip and that time is not until they are warm: I always have to keep that in mind when leaving the pits.

 

[panjandrum]

BTW: Online physics are not different, but the tires do act differently. Offline tires don't lose tread nor do they really ever cool off like they do online. I have been able to get online times within 0.2 of my best offline times in the first few laps after warming up the tires on the outlap. Tires online have a very narrow timeframe where they produce their best grip and that time is not until they are warm: I always have to keep that in mind when leaving the pits.

Thanks for those tuning specs, I'll definitely give them a try and let you know how it work out for me.

I don't want to get into the whole "are physics different or not" thing again here. It's best left to the other thread, but if you read it you'll see that a number of us have extensively tested that and it's definitely not just down to tire wear or tire temperature or fuel weight. Some extremely complex interaction is going on between certain types of cars and certain tracks and some parameters which differ between online and offline physics. Luckily I drive several different RR cars in real-life and in amateur motorsports, so I know the handling characteristics of these machines incredibly well. So I've got a good amount of real-life on-the-limit tarmac and ice handling data to go on here, and trust me, at least for the RR cars something is seriously wrong with the online physics (they aren't even close).

 

[Stiggles]

Thanks for those tuning specs, I'll definitely give them a try and let you know how it work out for me.

I don't want to get into the whole "are physics different or not" thing again here. It's best left to the other thread, but if you read it you'll see that a number of us have extensively tested that and it's definitely not just down to tire wear or tire temperature or fuel weight. Some extremely complex interaction is going on between certain types of cars and certain tracks and some parameters which differ between online and offline physics. Luckily I drive several different RR cars in real-life and in amateur motorsports, so I know the handling characteristics of these machines incredibly well. So I've got a good amount of real-life on-the-limit tarmac and ice handling data to go on here, and trust me, at least for the RR cars something is seriously wrong with the online physics (they aren't even close).

Well, the one big problem with the cars in game: all cars have the same alignment regardless of drivetrain or weight balance. A Porsche should not have the same alignment as a Civic.

I did notice the cars not driving correctly. Online is slicker, so it magnifies the problem of the bad stock settings (I still think it's just tire temps because a well set up car behaves correctly while a badly set up car goes to hell quickly when the tires don't heat evenly and it completely changes the handling, but that's for another thread).

That disparity is why I went and researched the real life alignments and suspension settings. When I found the real life settings so far removed from the in-game ones I just plugged the RL numbers in. They do tend to bring the cars back to what you would expect. Porsche was very easy to find (except the 930 since it had no coil springs), so were BMW, Honda, Subaru and, to a lesser extent, Mitsubishi. On all the brands I listed I've tried this method and it works, sometimes turning what was once a porker into a gem (Mitsubishi Evo IX), other times just making the car slightly less horrible (BTR).

I would recommend for every car finding the real life alignment and spring rates (if possible) as the first step in any tune. Those parameters usually fix handling problems outright, or at least get you much closer to something one can call "drivable". (Why spend tons of time shooting in the dark when rooms of engineers have already done the exact same problems and published their answers?) Also, on tuner cars, I find it fun to play with the settings of different aftermarket spring setups. It's kinda cool to pit Tein Springs against Prodrives against Eibachs and see the results so quickly; Tein won on the Ver VI Impreza in my tests.