Understeering on slicks - advise needed :-)

[RStom - Hungary]

Hi,

I have taken my almost stock car to the Pannonia-Ring in Hungary for a time attack This is the first trackday with my car, here is some onboard video..

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As You can see I have been fighting with strong understeer in long corners during acceleration:redface:
It would be nice if I could eliminate it or reduce, so I need your advice:biggrin:

Here is my setup....what would you change

Suspension:

Bilstein with eibach springs
SOS sway bars (both in the fron and the rear at the sofets position from the 3 adjustable point)
NSX-R chassis bars

Front :
Camber : -1.5 ° / -1.5 °
Toe : -1.0 mm / -1.0 mm
Rear :
Camber : -2.5 ° / -2.5 °
Toe : +2.0 mm / +2.0 mm

Wheels & Tires:
Work CR-Kai 17/18
Dunlop slicks 230/605/17
Michelin slicks 30/65/18

The outher side of the tyres are still have some wear...maybe I shoud add more negative camber...:redface:

Thanks in advance
Tamás

 

[ChopsJazz]

Tamas, without watching your whole video and dissecting it, my first comment would be that you may want to consider using a matched set of rubber. IMO, it's never a good idea to drive on mismatched tires.

HTH

Okay, after watching a little more of the video I'll ask a couple questions.

1. Are you rev-matching at every downshift? You seem to get loose at corner entries where you don't seem to rev-match. Maybe this is the understeer you are experiencing?

2. Did you pass a formula car at 2:20?

 

[nsxtasy]

In the NSX, understeer can quickly change into oversteer.

Do you have access to a driver training program which uses a skidpad?

 

[stuntman]

I really don't think it's that bad to run mis-matched tires or brake pads. With that having been said:

What are the rear tire width equivalent to? (Front is a 230, is the rear comparable to a 300?)

From watching the video, the exit understeeer is dictated by your entry and mid-corner. Early in the video, you over-slowed the entry of the corners, picked up throttle (which transfered weight/grip to the rear and took away front grip), and went through the entire corner on throttle. This is a very "Safe" technique that many beginners and club-racers use.

The second half of your video was much better. You started to carry more entry speed and picking up throttle later in the corner and a few times you carried really good entry speed and the car rotated into neutrality:

1:40
9:45
10:00
11:55

As a whole, you are still picking up throttle too early and not carrying enough entry speed. Work up to it slowly since you are driving quite well and going fast but need to work on a few things.

-Carry more entryspeed into the corner.

-Stay OFF THROTTLE until you get closer to your apex. This will shift weight to the front of the car, improving front grip, (but too much can cause entry oversteer so be careful and slowly build up to it). Because you have more front grip, the car will rotate mid-corner and you will be pointed down the next straight sooner.

-Pick up throttle later. Now that you have made it further into the corner (because of more entry speed and off throttle) and that the car is rotated mid-corner and pointed down the next straight. You have less turning to do from the apex to track-out and will thus have less understeer on exit.

-*TURN THE WHEEL. Especially since the NSX does not have power steering, it is even more important to not 'give up' and think you are at the limit of the car because its physically too hard to turn it anymore, but rather: YANK THE WHEEL and turn it harder and further than you think the car has grip for. At the above times you are did a better job, but the majority of the video you can tighten the line and the car WILL turn even better if you just physically turned the wheel even more.



*This is all fundamental vehicle dynamics and shifting from the driving techniques of club-racers and HPDE to relying more on your inputs and using the car and tire's grip more effectively - maximizing the car through the entire corner. But again, with the above advice, if you start giving the car the wrong inputs, it can bite you much harder than the safer technique of being on throttle through the entire corner.



Billy

 

[RStom - Hungary]

What are the rear tire width equivalent to? (Front is a 230, is the rear comparable to a 300?)

The second half of your video was much better. You started to carry more entry speed and picking up throttle later in the corner and a few times you carried really good entry speed and the car rotated into neutrality:
Billy

Hi Billy,

First of all thanks for your feedback!

• Regarding the tires yes the front is 230 and the rear is 300.
• It is great that somebody who can really drive and knows the NSX well, can give me some hints I'm very happy about it
• This was my first time at this track so I had no idea about the corners and it was only 1.5 hours on this track, and my car is a stock one and drove only about 2-3 fast lap than cooling dow a bit for few laps. This track on the other hand is known as one of the most driving skills demanding track in this part of Europe. The camera can not give back the hills on the track and few corners are blind one by beeing long. This is not to defend myself, because my aim is that I WANT TO LEARN and not ashamed that I have a long way to go. But I do it as a hobby beacause I like it a lot and love my NSX
• Watching back the video many time with your comments I make so many mistakes....it is great because it means that I can drive much quicker around the track, just need to practice a lot and aksing your advice

Thanks for your time again
Tamás

 

[RStom - Hungary]

-Stay OFF THROTTLE until you get closer to your apex. This will shift weight to the front of the car, improving front grip, (but too much can cause entry oversteer so be careful and slowly build up to it). Because you have more front grip, the car will rotate mid-corner and you will be pointed down the next straight sooner.

-Pick up throttle later. Now that you have made it further into the corner (because of more entry speed and off throttle) and that the car is rotated mid-corner and pointed down the next straight. You have less turning to do from the apex to track-out and will thus have less understeer on exit.
Billy

In the ideal way let's say in a not very long corner. Having more entry speed into the corner, the throtle pick up should be close before the apex, or at the apex, or close after the apex?? (with this setup of the car). Or before the corner brake, than starting to turn the car and try to maintain a constans speed (not to trasfer the weight neither to the front or to the rear) and from the apex start to accelerate???

Is there any good site where I could learn,read more about it?? Even if it is very detailed as I would like to understand all the details. (I also have a physics teacher graduate)

Thx
Tamás

 

[RStom - Hungary]

From watching the video, the exit understeeer is dictated by your entry and mid-corner. Early in the video, you over-slowed the entry of the corners, picked up throttle (which transfered weight/grip to the rear and took away front grip), and went through the entire corner on throttle. This is a very "Safe" technique that many beginners and club-racers use.

Billy

Hi,
It is me again..

Could you give me some really BAD example as well!!?

Thanks
Tamás

 

[stuntman]

"Constant speed" though a corner is a very old technique that is slowly starting to be phased out of practice in many racing schools over here in the states. Trailbraking (Braking slightly later and threshold braking in a straight line; then trailing off the brakes as you get down to the apex) has many advantages.

In short: In most corners, you do not want to pick up throttle until you reach the apex. In higher speed corners, you might carry as much entry speed as you can while being off throttle - coasting down to the apex. If it feels slow and really easy - increase your entry speed. In slower corners, you will trail the brakes down to the apex. Again, if you overslow the entry when trailbraking down to the apex - carry more entry speed.

Being on throttle or maintenance throttle puts weight and grip off the front and onto the rear = understeer when you want the car to turn.

More weight on the nose = more front grip = car will rotate better = less understeer. Too much can = oversteer. When entering a corner to get down to the apex, you want the car to turn. Thus, you want to have weight/grip on the front of the car to help it turn. The trick is balancing this and keeping the car 'dancing' on a tight-rope between over and understeer.

It is easier to practice this (and being more aggressive with the steering inputs) in lower speed corners. Slowly build up to it in higher speed corners.

That track looks like A LOT of fun. Good medium and high speed corners. I'm very jealous. But with these higher speed corners, they will require slightly more entry speed and coasting to the apex (improving front grip) to be driven properly and this is not as easy as a lower speed track.


Don't be too hard on yourself, you are driving the nsx quite well in your video. It's great to see people actually enjoying their NSX like this - on track



Billy