HELP: Audi TT Cup understeer

[RasmusP]

Hi,
as you all can see we had some good discussions going on in the last days and the consensus was something like "Let's have a place to talk about the driving".

So here I am, creating the first of that threads:
I need some advice on fighting the understeer in the Audi TT cup
When I watch the replays I see that "the fast guys" are having a better line and when I compare it to me in detail I see they are faster while cornering, turning in point + braking is almost the same and I see no clear difference.
It's like some "magic" that pushes them tighter around.
But then sometimes I get that too... Just don't know how to do it consistently

My thoughts: when you brake you will gain grip on the front wheels. So touching the brakes slightly while cornering will give you a tighter turning radius but will also slow you down. If you brake too hard you will transfer too much weight to the front and you will get understeer.
If you accelerate you will get understeer because the front wheels lose weight and therefore grip.
If you accelerate too much you will get HEAVY understeer, because FWD...

So somewhere in between there seems to be a "trick" that lets you do the "tighter turning radius" you get when touching the brakes, but without braking and without slowing down.

Can you help out? Do I have to turn the wheel more aggressively or trail brake deeper into the corner? I don't know and before I'm spending a few hours on doing a splitscreen slow motion video, studying the details etc. (maybe I will do that either way) I just thought about asking you all and start a nice discussion about the handling of our beloved (and sometimes hated) friendly event car

 

[Neilski]

Posted before I read Brandon's statement, I will give it some thought.

If you post a video of your lap, you'd probably get some useful tips.

 

[RasmusP]

@Kek700 send me the names in a pm please, I will do a up/down splitscreen comparison in slow motion so we will see every damn centimeter the faster guys is gaining

 

[Neilski]

If they have higher top speed at the end of the straight

I'd be inclined to compare speeds much earlier, like shortly after the car straightens up (maybe a few seconds at most) because by the end of a straight, both drivers will be near the terminal velocity and there won't be much to choose between them.

 

[Brandon Wright]

I'd be inclined to compare speeds much earlier, like shortly after the car straightens up (maybe a few seconds at most) because by the end of a straight, both drivers will be near the terminal velocity and there won't be much to choose between them.

Yes there will, if one of them is 2-3mph faster on the exit he'll be faster at the end of the straight. There's an excellent demonstration of this in the Skip Barber Going Faster video. They will not reach the same terminal velocity (unless they're topping out), the one with the better exit who got on the throttle sooner will have a higher trap speed.

 

[Neilski]

Yes there will, if one of them is 2-3mph faster on the exit he'll be faster at the end of the straight.

Absolutely, true; I don't mean to imply that the speed differential gap will vanish, simply that it will be shrinking all the way down the straight. IMO the first decent landmark (white line, road-surface change, kerb end, whatever) you can choose after both cars straighten up will give you the clearest indication of who got the best exit.

 

[Kek700]

That is what i was specifically looking for brandon, that is why i did it in very slow motion.
On the longer straights i found no difference in speed , start , half way , final max speed.
That is what shocked me and i find baffling, the extra speed needs to be an extra constant 2 to 3 km/ hr
Virtually every where. the last thing i did was time the whole lap at the same slow motion speed , and it agreed same 3 second quicker.

I do not want to cause too much trouble, especially as i probably have not done something correctly.

I set out expecting an obvious answer.

( i used the speedo on the car the specific car i was measuring )

 

[RasmusP]

I do not want to cause too much trouble, especially as i probably have not done something correctly.

Too late, I am hooked
Please tell me the names of the drivers and maybe laps where you didn't see a difference. Video will/would be online tomorrow afternoon (16 hours from now)

 

[Brandon Wright]

Absolutely, true; I don't mean to imply that the speed differential gap will vanish, simply that it will be shrinking all the way down the straight. IMO the first decent landmark (white line, road-surface change, kerb end, whatever) you can choose after both cars straighten up will give you the clearest indication of who got the best exit.

I think you may find the opposite, the gap increases. The driver with the better exit started accelerating sooner and has been accelerating for longer by the time they hit the braking point.

Skip to 2:07 in this video to see an illustration of how dramatically a better exit speed can impact your time down the straight. 2mph faster exit speed is good for nearly half a second.

 

[Mr Deap]

I do apologize for boring you all with this especially as I have no conclusion

“People think that practice makes perfect. But if you are practicing the wrong thing, you will be perfect at doing the wrong thing. Perfect practice makes perfect!” – John Boston https://www.worldtimeattack.com/index.php/so-you-want-to-go-time-attack-racing/

 

[RasmusP]

Well I think you just misunderstand each other. Of course the difference will be the biggest at the end of a straight. But in this case the Audi TT is significantly less accelerating when it goes above 180 km/h. Therefore the speed difference will be the biggest around that speed. After that the slower car will "catch up" in km/h.
The TIME difference of course, is another thing and will be bigger at the absolute end of the straight.
With the Audi TT it's not really about the highest km/h, but about who reaches 180 km/h earlier.

 

[Stig Bidstrup]

Dont know if I have over looked it ?? ,But all this Turn in talk and brake bias ,EDIT: understeer , will change if you use any assists ? --autoclutch ? --autoblip ? , if I start to use autoblip for excample I will go slower , because I am not used to using it--so suddenly ( if autoblip is on ) I wont have any engine braking when going down in gears.
same goes for autoclutch , So try with---and then try with out ,if you use any of it ? I dont know

 

[RasmusP]

Dont know if I have over looked it ?? ,But all this Turn in talk and brake bias , oversteer , will change if you use any assists ? --autoclutch ? --autoblip ? , if I start to use autoblip for excample I will go slower , because I am not used to using it--so suddenly ( if autoblip is on ) I wont have any engine braking when going down in gears.
same goes for autoclutch , So try with---and then try with out ,if you use any of it ? I dont know

Good suggestion!
Afaik in the Audi it doesn't matter because it only has 2 pedals in real life and automatic dual clutch transmission with sequential paddle shifting. In the mx5 cup it does make a lot of difference!

 

[Stig Bidstrup]

Good suggestion!
Afaik in the Audi it doesn't matter because it only has 2 pedals in real life and automatic dual clutch transmission with sequential paddle shifting. In the mx5 cup it does make a lot of difference!

Aaa Okay I have not tried that car yet ,If it have Traction control ??? can also give you understeer

 

[RasmusP]

Aaa Okay I have not tried that car yet ,If it have Traction control ??? can also give you understeer

Since it's frontwheeldrive it get's more understeery, the more throttle you apply. Therefore I have TC on (it has it in real life too)

 

[Stig Bidstrup]

Since it's frontwheeldrive it get's more understeery, the more throttle you apply. Therefore I have TC on (it has it in real life too)

Frontwheeldrive , TC , Automatic Clutc --is it Ladies Cup --No just kidding , guess I have to try it myself before I say more about this Car , good topic you have started here Rasmus

 

[RasmusP]

Frontwheeldrive , TC , Automatic Clutc --is it Ladies Cup

If even I could get MY Lady into racing...
But you are right, it's the most relaxed racing I have ever experienced! Best you can have after midweek stress

 

[Kek700]

I will be on assetto corsa teamspeak 13:30 uk time

If i have got it all wrong just shoot me, none of that hung drawn and quartered
nonesense

I might get a free driving analysis

 

[Feco]

Nice topic you started here @RasmusP .

I've found myself struggling with understeer in many cars, specially on the Porsche's ( despite of the rear engine ) - never tried the TT, but I'll give a shoot today.
Analyzing some videos and reading this topic I noticed that is my driving line that is affecting my race and causing this understeer.
I guess I'm not hitting the apex at the correct position by starting the turn to early and sometimes going full throttle earlier than it needs..Need to practice more!

 

[Neilski]

I think you may find the opposite, the gap increases. The driver with the better exit started accelerating sooner and has been accelerating for longer by the time they hit the braking point.

That looks like an interesting video - I must watch some more of it.
I think though that you misunderstood me - I was talking about the speed gap, not the time gap. The latter will indeed increase, but the former will decrease because the car's acceleration decreases as speed increases. (That section of the Skip Barber video says nothing about how the speed changes between start and end of the straight.) NB: I'm talking about the apples-vs-apples comparison of looking at the speeds of both cars at fixed marker points on the track.
The pic below is from a test-track run of a TT Cup, and you can immediately see how the slope of the speed curve is steadily reducing as the speed builds.

 

[Kek700]

Audi TT cup Nurburgring GP 30/06/2017 assetto corsa rookie class.

Fixed setup

Speed across start/ finish line = SF

Speed half way down long straight = SHS

Minimum corner speed = MCS

Minimum corner entry speed = MES ( you could consider this as entry speed )

Speed in KPH

These are my speeds, Rupe Wilson was in front and we did a similar time.

I'll leave you to work out were each measurement was taken on the track.

I cannot comment on " ping, accuracy of, playback , software foibles, etc etc "

There are bound to be small errors it is a very laborious task running this in slow motion.

I did not time the whole lap of each person, but i have done it before so i must assume it will tally.


Yes i know i am slow on the last chicane, i find it difficult to smash the car over the

Curbs there. It is not that i cannot do it , i just have this weird sense of caring about

The car i am in.


I hope this shows how almost impossible it is to really come to grips with why someone is quicker, i think it is just magic.

If anyone has a conclusion to all this please inform us all, i more than happy to admit i am stll
Totally baffled.


This stops people focusing in on setup as the total answer to lap times, these are
Fixed setup cars, just tyre pressure, also you have to use "paddle shift" gearbox

People use manual box, going from 5th into neutral then at the right moment select
3rd gear allowing them clean 100% braking, so we can discount that.

These results both come from the last lap.


I'll leave Rasmus to sort out understeer.....

Sorry if it does not come out propely when i dinally post it.




Ew ( 2min 11.43 sec ). Fastest driver ( 2min 09.75 seconds )


SF 162..........154

SHS. 204..... 195

MES. 213.... 210

MCS. 71...... 58

MES. 116......109

MCS. 105.......104

MES. 145....... 138

MCS. 76.........68

MES. 99......... 95

MCS. 99........ 95

MES. 178. .....175

MCS. 130.......124

MES. 138...... 128

MCS. 94......... 89

SHS. 195........ 183

MES. 200........ 192

MCS. 84..........75

MES. 161........ 160

MCS. 159........159

MES. 192........ 194

MCS. 113.........112

MES. 136........ 133

MCS. 119........ 112

SHS. 196.......... 194

MES. 205......... 212 (no not a mistake)

MCH. 82..........100. This is the final chicane

MCH. 81......... 79. Very difficult to access.

MES. 136. ......140

MCS. 95.......... 90

SF. 160........... 154

I am of on holiday.