Brake strength

[cotharyus]

I'll append this here. There should be a note in my post about all the cars that says the G4 has way too much braking power.

edit (thelusiv): split from Automatic transmission topic into its own thread

[thelusiv]

I'll append this here. There should be a note in my post about all the cars that says the G4 has way too much braking power.

Are you sure about that? Most of the other cars have way too little braking power. Most of them won't even lock up the brakes when you stomp them at high speed...you can tell because ABS never comes on when braking in a straight line on many cars. Really we should fix this before next release...

[cotharyus]

Ok - yes, most of the cars have way too little - however, even using an analog control (which works very well for throttle) and speed sensitive low settings, I can only just barely touch the brakes on this car before they lock up. I'd say that's coming on a little strong.

[joevenzon]

catharyus: can you fiddle with the friction value under the brake section in the G4.car file and let me know what seems to work best for you?

[cotharyus]

Yes, I'll mess with that as I get time - likely tomorrow evening, if I get lucky.

[cotharyus]

Ok - after some fooling around with break frictions on a couple of cars and making some notes:

The G4's brakes are about right. The problem I seem to have with the G4 is that any amount of braking seems to cause the (already very loose) rear end to step right around. The cure? It's downforce folks. I don't know who is in charge of specs on this car, and exactly what all the numbers mean, but when I change the -0.5 on the lift-coeffecient to 0.9 on the rear wing, the whole works gets a lot better. Part of my wondering about this number is looking at the same number on the AX2 (defidently not enough brakes on here) it is an even -2.

On that note, I upped the brake friction on the AX2 to 0.92 and it was much better. Still not stopping the way I expect a _race_ car to stop, but better.

So - who comes up with these values, and where do the values come from? How open are we to changing some of these values until they are reasonable? I realize that based on what I've read about some of the cars, that downforce might just be masking some problems in suspension geometery, but we have to start somewhere.

Also on a side note, what, exactly, is the AX2 supposed to be? It certainly seems like it could stand some taller gears, as it tops out very quickly.

[thelusiv]

The G4's brakes are about right. The problem I seem to have with the G4 is that any amount of braking seems to cause the (already very loose) rear end to step right around. The cure? It's downforce folks. I don't know who is in charge of specs on this car, and exactly what all the numbers mean, but when I change the -0.5 on the lift-coeffecient to 0.9 on the rear wing, the whole works gets a lot better. Part of my wondering about this number is looking at the same number on the AX2 (defidently not enough brakes on here) it is an even -2.

Downforce might be a good solution, but I think that changing the value for the rear wing from negative to positive will make it give more lift, not downforce, if i understand correctly. Wouldn't more lift in the rear make the back even looser? Maybe I misunderstanding how the downforce works.

So - who comes up with these values, and where do the values come from? How open are we to changing some of these values until they are reasonable? I realize that based on what I've read about some of the cars, that downforce might just be masking some problems in suspension geometery, but we have to start somewhere.

For the most part, whomever imports a car or creates it will decide how its values are set up. When importing Racer cars, we can usually reuse many of the values in the Racer car definition. As much as possible we try to get real world values from real cars to base our values on, but in some cases we have no way of obtaining real-world data, so the values are usually copied from another car that works, and then adjusted until the new car feels right. dmaurer/kcid imported many of the cars we have right now, the others were set up by Joe or me. If you want to know about a specific car, the best way to tell is to see who checked it in to SVN. Just go to the cars directory and look at the revision history for a given car.

Also on a side note, what, exactly, is the AX2 supposed to be? It certainly seems like it could stand some taller gears, as it tops out very quickly.

The AX2 is not a real car, it was imported from a Racer (I think) but I can't find the original right now. kcid imported it...

[joevenzon]

Cotharyus: I hope you meant you changed the -0.5 to -0.9, for the reasons thelusiv noted.

The downforce settings for some of the sleeker cars may be wrong. I'm not sure if the G4's setting is from the racer car or if it's just built using the GT as a template (the GT was the first car and its settings were used as a template in some cases). If it was using the GT as a template, then I think you're right to decrease the downforce.

By the way, when you're making your evaluations about the G4, are you comparing them to the way the GT40 is supposed to handle? Because keep in mind that's a very squirrely car to drive (at least it is in GT Legends)....

[kcid]

The AX2 is a car that I've found on the internet. It's also used in some form in Torcs. It's not a real life car. It looks a bit like a 24h Le Mans car to me.
For the G4 I used the GT as a template yes. I always try to find as much info as possible about a car and then change it accordingly.

[cotharyus]

Ok, to clarify, I did in fact mean -0.9 for the value I changed it to - my question about what all the numbers mean was more a refernce to units of measurement. I'll offer up this for your consideration, it comes from an article about the Lola T70:

The rear body shape was the result of lessons-learned from the GT40 project and its handling on the Mulsanne straight at Le Mans. It was designed to eliminate some of the lift created a high speeds. The GT40 created 300 kg of lift at speed while the Lola T70 only created 200 kg of down force though it did increase drag.

So, actually, the light rear on the GT40 at speed is probly pretty accurate.


So if the AX2 isn't real, that means we can adjust the brakes and gearing as needed? Because it does _real_ well with some brake friction cranked onto it.

[joevenzon]

i'd say go nuts with the AX2, make it drive like you think it should

[cotharyus]

You asked for it. No "major" changes, I fiddled some with the ratios and added a 7th gear. I took some liberties based on fhe fact that it's a "made up" car, but I didn't do anything unrealistic, I don't think. Drive it and tell me what you think:

http://wilderness.homeip.net/cotharyus/AX2.car

[thelusiv]

The brakes are much better now, and 7 forward gears!!!! Madness!!! :o hock: 8) :lol:

Checked it in.

[cotharyus]

Yea, the brakes are nice now. You can stop it without completely locking things down, but it will lock them down very quickly. The 7th gear is really only any good at all at lemans and at the nord. - no place else really lets it wind up enough. I added a touch of downforce on the nose - at mid speeds, it makes the rear end a little looser, but at higher speeds, it really stabilized the front end in turns.

[kcid]

I like the settings of the AX2, really good what you did man.
I'm a better 3d modeller then physics man