AC's Group C cars .... Why such poor Mechanical Grip ?

[JayMonkey]

Hi Guys,

I'm confused and a bit frustrated with the Grip Level of AC Group C's cars ...

I'm working with a real life professional driver who will be driving a Group C car at Le Mans soon.
He tested in the real car a few weeks ago at Silverstone GP and although it was the first time he'd driven it he was able to achieve lap times below 1:53:00 after getting used to the car.

Last week he wanted to do some practice in a Group C car on AC ....

We tried all of the Kunos Group C cars and some 3rd Party ones but all of them seem to suffer from very low mechanical grip and would loose traction very easily in low - mid speed corners.

No matter what we did with the setup we were unable to get anywhere near a real life lap time. Even with the Mercedes C9 (which seemed to be the best of the bunch we tested) he was at least 10 seconds short of a competitive lap time.

We don't have this issue with GT3 cars (he drove one in the British GT Silverstone 500 last week) ... with a good setup his lap times were bang on what he could do in real life.

So on to my question ... is there some trick to setting up AC's Group C cars that we are missing ? Does anyone else think that the Group C cars have low mechanical grip ?

In real life these cars have huge fat sticky slick tyres .. they should have more mechanical grip than any other car in AC ... but they feel like driving a boat on a wet track ... indeed the pro driver i was working with said that the real life car was far easer to drive than the simulated one in AC ... So what gives .... any tips, setup or suggestions would be most welcome .....

I should point out that we are running AC on a custom motion simulator with OSW wheel, professional pedal set with load cell brake pedal with real life stiffness ... as good as it gets in terms of sim equipment so i don't think its anything to do with the rig itself.

Appreciate any advice on this ...
Cheers
Jay

 

[LilSki]

Well you can throw the C9 out the window as it has lemans spec aero so on any other track it will be very slow. the 787b and the 962 short tail should be fine though. But do remember I believe they try to mimic era correct tires and not modern day rubber.

 

[Kek700]

I have always found the level of grip the group C cars provide :-
( mechanically far too low )
I also agree that the C9 is the most forgiving of all of them
I hope someone can answer for you and me.

 

[CobraCat]

Might be prudent to post this over at the official forums. I'm quite curious as well !

 

[mclarenf1papa]

Would need more information about the real car to say anything definitive. Shoot me a PM with some more info (about the car and its tires IRL) and I should be able to help.

Just for context, I've worked with a number of real life teams on LMPs in AC and I'm working on the Group-C mod here on RD.

 

[Viperion]

I'm working on the Group-C mod here on RD.

Oooooooohhhh

 

[JayMonkey]

Well you can throw the C9 out the window as it has lemans spec aero so on any other track it will be very slow. the 787b and the 962 short tail should be fine though. But do remember I believe they try to mimic era correct tires and not modern day rubber.

@LilSki,

Even if the aero is optimised for LeMans this car should still have outstanding mechanical grip so it should at least be drivable at up to 95% (or more) at somewhere like Silverstone GP.

A good indication of the issue is the chicane complex before the start finish straight of Silverstone GP, its a slow entry into the first corner of the complex (under heavy braking) then careful throttle control round the 2nd corner and then almost flat through the last part of the complex on to the start finish straight.

None of that complex of corners is high speed so mechanical grip is key and should not be an issue for any Group C car with a half decent setup. But all of AC cars handle awful through this complex of corners which is nothing like real life.

I find it hard to believe that kunos would release with such bad characteristics in these legendary cars which makes me think there must be some sort of odd set up tweak to get them working .. maybe something to do with dampers ?

Hoping someone out there can shine a light on this ...

Cheers
Jay

 

[mclarenf1papa]

@LilSki,

I find it hard to believe that kunos would release with such bad characteristics in these legendary cars which makes me think there must be some sort of odd set up tweak to get them working .. maybe something to do with dampers ?

Hoping someone out there can shine a light on this ...

Cheers
Jay

Well, the Kunos LMP1s are down about 100HP from where they should be (based off of known fuel flow and known thermal efficiency...or alternatively based on known drag and top speed; both give the same result), so it wouldn't be particularly surprising that they got cars with less reference (essentially only technical data and lap times) incorrect.

I seem to recall the C9's dampers needing stiffening, but not sure. That said, it's very likely a combination of LM aero (last corner at silverstone's not really that slow and LM vs. sprint downforce is a drastic difference) and some slippery tires. Like I said, PM and I can help.

 

[JayMonkey]

Would need more information about the real car to say anything definitive. Shoot me a PM with some more info (about the car and its tires IRL) and I should be able to help.

Just for context, I've worked with a number of real life teams on LMPs in AC and I'm working on the Group-C mod here on RD.

Hi mclarenf1papa,

I'll contact the driver and ask him to get in touch with the team and get some data for you on the car he is driving and will send you a PM.

Great news about the Group C mod your working on, hopefully your cars will handle (and grip) much better than the stock kunos ones and many of the lame 3rd party ones that are out there.

Any idea on a release date ... ?

Cheers
Jay

 

[mclarenf1papa]

Hi mclarenf1papa,

I'll contact the driver and ask him to get in touch with the team and get some data for you on the car he is driving and will send you a PM.

Great news about the Group C mod your working on, hopefully your cars will handle (and grip) much better than the stock kunos ones and many of the lame 3rd party ones that are out there.

Any idea on a release date ... ?

Cheers
Jay

Not even sure that I need data (though it may help with the mod so it would be nice! If telemetry's been logged that would definitely help get to the bottom of this particular issue), just what car it is and what aero configuration its running.

The mod's based on the late-year cars, so they're quite different from the ones from Kunos anyway. Release date's up in the air. The TS010 has physics that are somewhat release ready, but the model's not ready. The rest of the cars don't have polished physics.

 

[Glaurung]

In AC Group C cars have slick 90s tyres that provide less grip than modern ones.
Also, check your ride eights carefully, because these cars rely massively on ground effect.
I've managed 1.53.4 with the 962C, IIRC the lap was not that clean, so a round 1.53 or even below is definitely possible.

 

[JayMonkey]

Also, check your ride eights carefully, because these cars rely massively on ground effect.
I've managed 1.53.4 with the 962C, IIRC the lap was not that clean, so a round 1.53 or even below is definitely possible.

Hi Glaurung,

Thanks for your reply, we did check and work on the ride heights, the Group C cars seem to work best with a fair amount of front to rear rake in the ride heights.

A 1:53 round Silverstone GP is about right .... that's what my real life pro driver was achieving a few weeks ago during a test day.

We never got around to trying the 962 in AC .. so maybe we'll give that ago ... it does not really matter which Group C car we use in AC .... we just want something that has the Group C characteristics, IE 80/90's aero / big slicks / V8 twin turbo with a fair amount of lag, steel brakes .. etc ... so that the driver can do a bit of sim practice before the big race at Le Mans in a few months.

We've been testing the AC Group C cars at Silverstone as its the only circuit he's driven a Group C car at so far .. also its very local to us and we test/race cars their quite often in quite a few different classes so we know the circuit very well and know what we need from a car to get a quick lap.

Would you mind sharing the setup you used with the 962 ?

Will let you know how we get on ..
Cheers
Jay

 

[Glaurung]

On my experience a raked setup do not pay with Group C cars, especially the Mazda, that prefers a setup of the rear as low as possible.
The C9 we have in AC is the low drag spec, that works fine in high speed tracks like Le Mans, Monza, Spa, etc., Silverstone is not the best track for that beast, because requires more downforce and the 962C short tail is perfect for that.

 

[JayMonkey]

Might be prudent to post this over at the official forums. I'm quite curious as well !

Good idea .... link to thread on AC Forum :-

http://www.assettocorsa.net/forum/i...p-c-cars-why-such-poor-mechanical-grip.50157/

Cheers
Jay

 

[LilSki]

Good idea .... link to thread on AC Forum :-

http://www.assettocorsa.net/forum/i...p-c-cars-why-such-poor-mechanical-grip.50157/

Cheers
Jay

Sort of pointless as AC development is over. They aren't going to revisit anything in AC with ACC development in full swing.

 

[JayMonkey]

Sort of pointless as AC development is over. They aren't going to revisit anything in AC with ACC development in full swing.

@LilSki,

True but always good to know what the community thinks ....

Jay

 

[CobraCat]

Also, the devs could chime in and give more info. As the old saying goes, you never know until you try or in this case, until you ask!

 

[schrep1964]

I checked some historical data for the Porsche 956:

Car weight at the Silverstone event 1983: 820 kg, turboboost at 1.2 bar, tyre width F 280/600-415mn R 350/650-415mm, drag coefficient 0.35-0.40, high downforce carheight 1080mm, ground clearance 55mm F and 145mm R (racked f to r), total max downforce around 6000lb, springs F 220N/mm R 170N/mm, damper tension F 600/250 R 500/250 high downforce, gears 17/34 18/25 16/28 28/25 30/23 F 8/37.

Maybe check and alter the data file and run it again.

 

[Tberg]

The C9 drove a 3:15.040 lap on Le Mans in 1989 (no chicanes), that was the fastest qualifying lap it did.
Few days ago, I drove same layout 3:20.xxx on Medium tyres in AC on default setup + longer gearing. On soft, it was able to go sub 3:17.
I'm quite sure the mechanical grip will be different from a real C9 with current tyres to AC's model with simulated older tyres. That goes for all the Group C cars in AC.

 

[Richard Dastardly]

Didn't Silverstone get resurfaced recently with higher grip tarmac? I'll also echo again that I think these things are using 80s vintage rubber, does your friend's car have the same compound?

But then again I dont know where they got the tyre data from for the AC tyres, maybe they're just not right. I doubt the underbody airflow is modelled anything like a Group C car's venturi tunnels either - a wing is not going to be as sensitive to ride height for one and there won't be the tunnel/wing interaction you got on the later biplane wing cars.

AC's Le Mans is too long, no comparison there. I'm trying to think of one of the laserscan tracks which hasn't changed layout since the 80s... perhaps Laguna Seca & dig up some later IMSA times, although IMSA cars are not quite WSC spec. Mugello maybe?

956 is not a 962.