Formula-Retro drivability

After testing these cars yesterday after the release, and today doing some hotlaps and long runs with my friends, we got some conclusions about the handling.

In general the cars feel fine, with the expected understeer at low speed. It takes three or four laps to warm up the tires to an opperational temp. So, don't change the setup before doing five or six laps.

Braking before a turn must be gently, letting the engine slow down before downshift, other way the car will loss the line. You must release the throttle in the right moment to transfer weight to the front and get grip on the right moment. The corner exit isn't as easy as the size of the rear tires makes you think it will be.

Then when you get the right lap and line and you start to push the car, and very odd things happens. There is a very unexpected behaviour on mid speed corners. In middle of the corner and without any previous advise the rear of the car slides and you can't recover it. It feels really odd, there isn't any force feedback signal that let you know what will happen, it sudenly happens.

We tried several setup changes, height, dampers, differential, bump stops, bars, springs, but it never dissapears.

It could be the rear tires stiffness, tire grip, or something on the aero. We figured out that using the front downforce at 3 never can't be matched by the rear even at position 10. So the best aero balance is 2-8 to 2-6.

If you have some experiences like these, share your opinions.

 

What was the car, the track and the corner?

 

Formula 1970 cars are my absolute favourite in sim racing. The RF2 Brabham at the Imola 72 made by Reiza for RF2 is one of my all time favourite combos. In AMS2 the Imola 72 track is not up to standard at all, the bumps are so bad for all of the AMS2 open wheelers that even the AI trip over them crash and fly in the air. The physics of the seventies cars are below par too. At Imola 72, when you hit the first curves after the start finish straight if you slightly jolt the wheel to turn the car wipes out completely. I’ve driven in default set up, I’ve tweaked tyres and suspension and nothing stops wipe outs, even the AI can’t drive Imola 72, a lot of work to be done on the retro’s. In real life if they had handled like this an F1 driver would have died every race. I did try the Retro Mclaren at Kyalami 72 and there was a huge difference and it was genuinely fun so I’m very hopeful. I challenge any of you to drive the Brabham at Imola 72 and tell me it’s enjoyable. I’m hugely disappointed by the retro’s and Imola 72 especially when compared to the RF2 Brabham and the Imola Reiza pack for RF2, it’s made me appreciate even more how great RF2 is rather than thinking, go Reiza stick it to the big boy studios !

 

I had exactly this at Imola trying out the new Reiza Brabham BT44, flat out and hit the bump on the inside and the car spins, lift off a bit and you can hearing the screech of the rear tyres losing grip but it's possible to get through the corner. And the Ai go slow at this part of the track. I'm not convinced anything is wrong though. If you hit a bump and hear the bottom of the car touching the track it's a clue your wheels aren't necessarily on the ground, so you'd spin, if you lift off to avoid grounding the car you'd lose downforce, so the rear would get light. And Imola was a bumpy track. The difference between the nicer to drive McLaren and the Brabham is they are a generation apart. The suspension may not have evolved much, but the Brabham had much more downforce so it hits the bump in the track harder.

That is speculation of course, there may well be a fault with Imola and to be honest I've never had any other car swap ends on that 'flat out' corner before. But equally for the sake of argument it wouldn't be unusual at all for some older tracks to have major bumps in them, and Imola is in an earthquake zone so the land moves more. So that said I kind of like the idea the track isn't billiard table smooth, if it's real it's fine by me.

 

Those cars are completely undriveable in AMS2 at the moment. No real feelable and controllable weight transfer. No lift off oversteer, but massive understeer. Then sometimes the back snaps without any warnings.

I can throw the RF2 Brabham BT44 around the Nordschleife really fast, with heel and toe shifting and all. There you just feel the car and can drive it with your right foot and controlled weight transfers.

Completely impossible in AMS2.

 

I took the Lotus 72E and played around on Kansai (I think that's probably the best test track for cornering behavior right now) for a while, and this is what I found:

1. The advice to use a geared LSD - Absolutely, yes. This is the best of both worlds in a lot of ways. I dont know much about what the numbers mean on this one the way I do with the clutch LSD, but it pretty much feels the way I am trying to get my clutch LSD's to feel, but without any effort to finding ideal ramp angles and clutch counts and preloads!

2. The understeer is unbearable. I found that increasing front downforce to 3 lead to a great improvement at medium to low speeds, but at high speeds the car was very unstable. Increasing rear downforce to compensate seemed to balance it out pretty well. This cannot be tuned out, but it can be improved significantly.

3. Damian got me to thinking about this, but these cars were probably prone to this in real life, with gigantic rear tires and tiny front tires, I think with a tire model based sim, you get some obvious results from this. I think this is why some of the behavior feels so unpredictable. I'll explain below:

Slight amounts of high speed oversteer are nearly uncorrectable, as soon as the rear starts drifting under its own momentum, it is going to go where it wants to go. I have managed to overcorrect at times, but normally it just barrels to the inside of whatever corner Im going around. Very rarely am I able to actually save the car, unlike the Formula Vintage where as long as you apply countersteer quickly enough, you can almost keep cranking oppo lock as far as you want until it goes where you want it. it happens much faster, and requires a lot more precision with these F-Retros. Attempts to increase rear grip, in my limited newbish experience, seem to exacerbate the understeer problem.

However, if trail braking, these things will lose and regain traction very abruptly, and you can safely control extremely high angles of rotation. I had some crazy situations going into turn 2 at Kansai, and then I was able to go into the hairpin successfully nearly sideways a couple of times. Same with Spoon. Dab brakes going in, it will aggressively rotate, and you'll think you cant save it... feed in throttle and suddenly the car will start going the direction it's pointed!

Additionally, I hear complaints about no lift off oversteer in this game... that has NOT been my experience at all. Lift off oversteer is the best way Ive found so far to get the 72E through sector 1 at Kansai. The rear will slide outwards in the sweepers if you let off, and then you can feed in throttle whenever you like to get forward momentum again. I find myself going on and off throttle more than once to get it through Dunlop and the preceding corner.

So my conclusion to all this? These cars have HUGE rear tires with tons of rear grip. Drive the car with the rear. If the rear end is sliding out, apply throttle and it will grip and the car will go where it's pointing again. At high speeds you're going too fast to regain grip and it happens too quickly to save. I feel like in real life, if the car oversteers mid corner in a high speed corner, the car will spin towards the outside. But the rear tires have so much grip here, the car slides, then the rear grips again and since you're applying throttle (high speed corner, right? Think 130R), the tire has enough grip left to drive off the road where it's now pointed. It will aggressively drive off the road to the inside. I would imagine the faster you're going, the harder it is to save, because its so much harder to manage when and how the rear will regain grip. This is really the same behavior as at low speed, it just happens so much faster that you cant really use it to your advantage.

I dont know if this behavior is realistic or intended, but if you look at it from the point of view of how big the rear tires are on these through the lens of a tire model sim, it makes sense. What do you guys think?

In conclusion - for the 72E at least, crank up the downforce, use the geared LSD, know that the differential allows for plenty of rotation off throttle and it will aggressively lock on throttle. Due to how large and grippy the rear tires are, this has a profound effect on the behavior of the car. Increased downforce will give more grip and help with the high speed oversteer.

 

I did get good results with Geared LSD but it has a disadvatnage of not applying torque to wheel with traction that well when 1 wheel is off ground.

I would love to find out what kind of LSD these cars used back then.

 

That's interesting you mention that... Imola 72 is unusually brutal with the Formula Retros... Im not sure if Im imagining it or what, but I had so much trouble with the high speed kinks I went to Kansai to try to iron out the setup. Haven't taken that setup back to Imola 72 yet, but I remember people saying that different tracks would feel completely different to them... I wonder if thats happening here as well.

 

I can almost guarantee you that they used clutch plate type differentials. I could be wrong, but even today they're probably the most "tune-able" differentials you can get. Modern F1 uses some crazy planetary contraptions though.

 

I get what you are saying the bit that gets me is that Reiza created a imola pack for RF2 and it’s amazing for hot lapping or ai races. The track is bumpy but not to the point both a player and ai can die at any moment. I can’t get my head around how reiza smashed imola 72 out of the park for RF2 but for their own game ams 2 it’s a completely different track. Even if you race the v12s or the p3 rocos there the ai have the same issues, as do I but less than the retro formulas. From the start line to the first hair pin I’m flat out and only lift on the dark tarmac before the 100metre board with 2 downforce. In ams 2 flat out means spin out. I hope they make imola 72 the same way they did for RF2

 

what confuses me is how different these retro cars drive in rF2 and AMS1. Now which one is more correct?

in rf2 or ams1 I can dial the turn in really nicely at default preload with just coast setting and not a single sign of the terrible understeer.

 

I get the same behavior out of the Formula Retros going through 130R at Kansai as well, though. They're just prone to snapping out on you. 130R is really tough with the Formula v12 too, though.

I think they will probably revisit some of the physics of the Formula Retro tire model too. I dont think they should snap out like that and then drive you into the inside walls the way that they do. I dont think this is bumpiness at Imola, I think this is just the way they behave.I think these have a lot of potential, though.

The 312t in Assetto Corsa doesnt behave like this either.

 

Unfortunately that's not how RWD cars act in real life. If you gas it in a spin, it'll spin harder. But many (if not all) RWD cars in this game act in the way you described.

 

Romain Grosjean disagrees.

 

And the result speaks for itself.

 

Well not full throttle, just stay on it like half throttle, letting go of it will result in more pendulum effect(in AMS2) in the Brabham >3rd gear bends. I would not call that lift oversteer because it already was oversteering on throttle to begin with

IRL staying on throttle (not full but modulating)is the way to go in my rwd streetcar @ driftdays.... not talking bout when in an uncontrolled spin, talking about when being in a slide.

Cheers
Robin

 

Not necessarily true... if you can get the weight shifted to the rear, it will suddenly regain traction, if you regain a little traction you can shift weight to the rear. It's a feedback loop but getting it started is the hardest part. Whether this behavior is modeled correctly or not is definitely up for debate, though.

 

Well, yes and no....

When you accelerate in your personal car, what happens? The weight shifts rearward and you get pushed into your seat. When you slam on the brakes, what happens? The weight shifts forward. What happens when you don't hit the brake, but you quickly take your foot off the accelerator? Similar, there is engine braking so the weight shifts forward (but not as much as when braking).

If you start loosing traction in the rear, the last thing you want to do is to make the rear light by shifting weight forwards (taking your foot off the accelerator and/or applying brakes). Applying more acceleration when the rear is loose can add more traction and save a slide (and possibly keep it from turning into a spin). However, there is a point of no return where nothing will save a spin.

 

Even though I posted it more as a joke, you can actually see that in the Grosjean video. When he first lights up the rears, his rear end stabilizes for a second - only when he applies more and more throttle, the rear end loses grip completely and he crashes.

 

To be clear, I think this behavior is extremely exagerrated with these cars... but it has roots in real life physics.