Does your car react differnetly at different tracks?

[Hrant]

Following the thread regarding the sway bar setting, I was about to experiment with a different set up at last week's track event when curiously, and before doing a change, I ran the same set-up for a session to establish a baseline. I noticed that my car is reacting differently on the three tracks that I attend using the same set up at all three tracks.

Here in NorCal, at Laguna Seca it has a tendency to understeer, at Infineon it is almost neutral, and at Thunderhill it has a tendency to understeer at track out at certain high speed turns. These observations were all at ambient temps in the 60F.

How about your situations? Do you change your set-up depending on which track you attend or have you found a happy medium? Just as an FYI, mine is not a track only dedicated car. TIA.

 

[NSXDreamer2]

could that be related to your tire's traction, (new, Heat cycled but still have good depth, nearly blad??) I would expect the different track had different friction materials, dirt, or even track corners design (more bank??)

 

[apapada]

How about your situations? Do you change your set-up depending on which track you attend or have you found a happy medium? Just as an FYI, mine is not a track only dedicated car. TIA.

I personally adjust tire pressures and once I changed swaybar settings to make my car less oversteering. But proffesional racers do alterations to their setup all the times depending on the track and the weather conditions. Also, when 2 drivers are using similar cars on the same track the same day, some setups are better suited for a driver than the other.

 

[Hrant]

could that be related to your tire's traction, (new, Heat cycled but still have good depth, nearly blad??) I would expect the different track had different friction materials, dirt, or even track corners design (more bank??)

Nope. I am running the same OEM 17/17 street tires/wheels that came with 02+ and they have plenty thread since they were new.

I too adjust the tire pressures. But never gone as far as to adjusting sway bars for specific tracks.

Where are all the boy racers when we need them or was that a too embarrassing question to ask :wink:

 

[NSX-Racer]

Yes, the car reacts different on different tracks. Plus: It reacts different on the same track when the conditions change (temperature, damp etc. - often throughout the same day). I'm too lazy to change sway bar settings, I adjust tire pressures and - more important - my driving style.

E.g.: Less late braking when the car tends to understeer during turn in - slower in - faster out - that's usualy the case when the track has less grip (overall or in the morning). When the track is grippier I brake later and more into the turn. Just a little example.

 

[Chris F]

E.g.: Less late braking when the car tends to understeer during turn in - slower in - faster out - that's usualy the case when the track has less grip (overall or in the morning). When the track is grippier I brake later and more into the turn. Just a little example.

That sounds backwards to me. When I'm driving a car that won't turn, especially on a lower speed corner, I'll trail-brake 2/3rds of the way down to the apex if I have to, then get on the gas. This is in an effort to load up the front tires with weight, to get them to stick a bit, and let the rear rotate a bit because it's lighter.

I'm driving my car backwards (FF) so YMMV. If I'm wrong I'd love to hear about it.



Also-- Your car can act differently at different tracks. Banking was mentioned, and in fact you will find off-camber turns where your car just doesn't want to turn in. Braking zones can get choppy at some tracks and your car may decide to do a little dance under near-threshold braking. You tires may heat up differently at different tracks depending on what types of turns there are, etc. etc. You can also find different compounds of track (cement/asphalt/new asphalt) in a single corner that will make your car act differently from the beginning to the end of the turn

It's not like you're driving a whole new car, but subtleties come out when you're getting near the edge of adhesion.

-Chris

 

[NSX-Racer]

That sounds backwards to me. When I'm driving a car that won't turn, especially on a lower speed corner, I'll trail-brake 2/3rds of the way down to the apex if I have to, then get on the gas. This is in an effort to load up the front tires with weight, to get them to stick a bit, and let the rear rotate a bit because it's lighter.

I'm driving my car backwards (FF) so YMMV. If I'm wrong I'd love to hear about it.

This would be a topic for a different thread. Unfortunately my technical english is not good enough to clear up all the theoretics but the main thing is that if a tire is already busy with braking it doesn't love to change direction. In case of a FF car this may vary because you can force your front tires a bit to go in another direction by simply step on the gas (which is not possible with a MR car of course). The limit for your kind of turning in is of course described by the Kamm circle (you may understand it even if it is in german).

 

[mikeh]

Following the thread regarding the sway bar setting, I was about to experiment with a different set up at last week's track event when curiously, and before doing a change, I ran the same set-up for a session to establish a baseline. I noticed that my car is reacting differently on the three tracks that I attend using the same set up at all three tracks.

Here in NorCal, at Laguna Seca it has a tendency to understeer, at Infineon it is almost neutral, and at Thunderhill it has a tendency to understeer at track out at certain high speed turns. These observations were all at ambient temps in the 60F.

How about your situations? Do you change your set-up depending on which track you attend or have you found a happy medium? Just as an FYI, mine is not a track only dedicated car. TIA.

Yes, that's why people with race cars log/record a known 'good' wet/dry setup for each track, because they make adjustments from track to track. And then based off that known good setup, they fine tune it in their practice sessions before the race.

It's not that your car suddently under/oversteers, it's just the style of driving (or the line that needs to be taken) that changes between tracks tends to highlight different aspects of your cars turning/transition abilities.

If you're at the point of changing your setup from track to track, make sure you log/record it so you can keep track of the settings to start from at each track... have fun!

-mike

 

[Chris F]

This would be a topic for a different thread. Unfortunately my technical english is not good enough to clear up all the theoretics but the main thing is that if a tire is already busy with braking it doesn't love to change direction.

OK, a minor threadjack.. apologies to the original poster...

Let's make the assumption that weight transfer and friction apply to FF and MR cars the same

The circle you showed is called a 'friction circle' on this side of the Atlantic. The cool thing about it, is that you can change the SIZE of the circle by increasing/reducing weight on a tire.

Standing still, your MR car might have nearly equal friction circles on all tires. When you are just cornering (not accelerating/braking), the outside tires get a bigger circle since the weight on them increases, and the coefficient of friction (mu) stays the same. Front and rear friction circles keep their balance.

Extrapolating a little further, if you can shift weight to the front of the car (engine braking or brake-braking), you can get a bigger circle in front, a smaller circle in back, and cause the car to oversteer. This is why if you lift in the middle of a corner you will spin (besides the reduced traction in the rear tires because of the engine braking using part of the friction circle).

 

[Andrie Hartanto]

I agree with NSX-Racer. When the car tend to understeer, I brake earlier and go into the corner slower. I do tend to trail brake onto tight corners with understeer characteristics. One must differenciate between trail braking and late braking. A late braking is to use maximum braking at the latest possible moment. Early braking can be used with trail braking. The whole purpose of trail braking is to add load to front tires.

Go back on topic, yes, everything changes according to weather, track condition and track layout. On a street car, I don't do any changes, other than a quick shock adjustment and my own driving style.

On a race car, I constantly do anti-roll bar, shock adjustment, alignment and tire pressure changes depending on track condition and weather.

 

[ss_md]

Every track is designed to test the driver, the tuner and the car. So, if a car drove the same at all tracks: where would the challange be? That would make it too easy for almost anyone to race cars, motorcycles or whatever.

"It would be so easy - even a Caveman could do it". :biggrin:

 

[Hrant]

Exactly. I agree with the posts.

And since most of us occasional weekend trackers have for the most part similar mods (the range of mods for an NSX is not that huge unless it is a track dedicated car), and very few of us - except for Andrie here in NorCal, and Doug Hayashi and perhaps a few more in SoCal - have started tuning for a specific track, I was curious to know if others ascribe similar attributes or peculiarities to specific tracks when driving their NSXs.

Perhaps my post was not clear. I am particularly interested in knowing if certain tracks tend to have inherently more undersdteer or oversteer for an NSX - given all the other variables. I know it is tough to make such generalities but every track has its unique characteristics in handling.

 

[Chris F]

... I do tend to trail brake onto tight corners with understeer characteristics... The whole purpose of trail braking is to add load to front tires.

OK, I can agree with this for sure.

Perhaps my post was not clear. I am particularly interested in knowing if certain tracks tend to have inherently more undersdteer or oversteer for an NSX - given all the other variables. I know it is tough to make such generalities but every track has its unique characteristics in handling.

I can't answer for an NSX, but I'm going to chime in anyway. Out of the handful (7) of tracks I've been to, I haven't heard of one that would tend to cause more or less oversteer. A very fast track, a small/slow track, and an autocross could each merit their own setup though, depending on taste (I'd prefer a car to have a bit more understeer at a course with a lot of quick esses or high speed corners).

 

[apapada]

Perhaps my post was not clear. I am particularly interested in knowing if certain tracks tend to have inherently more undersdteer or oversteer for an NSX - given all the other variables. I know it is tough to make such generalities but every track has its unique characteristics in handling.

I can see some tracks better suited for a car like the NSX versus other cars. For instance at equal HP/lbs ratio, a short curvy track where lighter cars with low polar moment of inertia are more nimble and achieve better times that heavier cars with more HP. Or the other way around (tracks with fast corners and long straightaways where HP is king). But I cannot see why/how a track, by its setup and layout alone, can induce any car to oversteer or understeer more than another. When it comes to vehicle dynamics, it all comes down to vehicle setup and driving style.
Now, maybe a driver with a stock setup on a particular car might be better for a given track under certain conditions than another stock setup on a different car. But that alone accounts for far less than performing setup adjustments on either car and/or adjusting driving style. In fact, track characteristics change all the time during the day (temperature, previous traffic, dirt, water, ...) and so do the car's brakes, tires and driver (fatigue). The only times I find my NSX more oversteering than usual is at the end of the HPDE days when I'm dehydrated, sunburnt and my tires are getting greasy... :biggrin:

 

[nsxtasy]

I cannot see why/how a track, by its setup and layout alone, can induce any car to oversteer or understeer more than another. When it comes to vehicle dynamics, it all comes down to vehicle setup and driving style.

I agree.

 

[Andrie Hartanto]

But I cannot see why/how a track, by its setup and layout alone, can induce any car to oversteer or understeer more than another. When it comes to vehicle dynamics, it all comes down to vehicle setup and driving style.

When you setup a car for a track you are looking for compromise that resulted in fastest lap time. The car will behave differently on different type turn, decreasing radius, tight turn, fast turn, off camber and so forth. Some track have more one type of turn than other, thus dictating certain compromise.

The track condition usually changes troughout the day. Usually the changes is in temperature. Which dictate more on tire pressure. A tire will only have one range of optimal pressure at given temperature. Our goal is to achieve maximum grip in given temperature.

A car setup can also dictate fast lap time in a few laps or consistent run throughout the race. Like Qualifying setup is usually different than race setup. My qualifying setup is usually really on the edge. You have to drive the car fast and constantly on the gas or you'll end up spinning. But to run this setup in a race is taking a big risk with lots of traffic around you and constantly different line than the conventional fast line.

 

[NSX-Racer]

I can see some tracks better suited for a car like the NSX versus other cars.
But I cannot see why/how a track, by its setup and layout alone, can induce any car to oversteer or understeer more than another. When it comes to vehicle dynamics, it all comes down to vehicle setup and driving style.

Agree with your first point.
For your other point: I guess different surfaces and grip levels of tracks can alter the cars behaviour. E.g.: There's a track in France called "Mas du Clos" that is extremely grippy (and tire abbrassive) over the whole length. On this track I never experienced any sign of understeer in all corners but remarkably more turn in oversteer than on other tracks.

OTOH: In Magny-Cours where the track is much less grippy there are several turns where the car tends to understeer (with the same setup, tires and comparable temperature conditions). This effect gets even worse when the track is damp or wet (especialy in Magny-Cours).

The same occured in former times at Spa-Francorchamps when part of the tracks where public roads (most of the year when it was not closed for track events) and less grippy than the track only parts. On the track only parts the car was about neutral wheras I experienced some understeer at the "public" parts. Nowadays that has changed because the whole track is non public and they renewed some of the surfaces.

IMHO that has to do with the grip level of the front tires on a given track. Nsxtasy may remember that old thread where we talked about changing to grippier tires at all four corners of the car. This usualy results in less understeer because the effect is greater for the front although the rear tires are stickier too. I claim this to the same effect as a grippier track.

Please correct me if I'm wrong.

 

[Hrant]

After reading these posts, my theory seems to be correct. Please note that my initial post set the parameters of the scenario:

I noticed that my car is reacting differently on the three tracks that I attend using the same set up at all three tracks.

Sure, the tracks are what they are. Some are suited for HP and some for balance. The track itself does not make a car understeer or oversteer with proper track/day specific condition set-up. Once you change the varaibles the question becomes somewhat moot.

But my question was once you find a compromise in the set-up (for street/track use as in alignment, sway bar, suspension, etc.,) the available adjustments are not too many if you don't want to keep fussing with track specific set-ups. And with such a compromised set-up tracks will inherently react differently given the same set-up and same driver. In this scenario the car/driver is not the variable, the tracks are ..... if it makes some of you happier, the flip of the coin is the car will react differently at different tracks with the same set-up but that would be a no brainer question ;-)

 

[92 white 0650]

a no brainer question ;-)

Hrant, where's the detailed analysis of Monday's Laguna event? I'm still dealing with jet lag, can't get to sleep, and a post from you should help me nod right off.

 

[Hrant]

You missed a good one Ted.

Six of us caravaned from Sacto with Kip hauling his trailer (and there is a story to that as well), and Greg Strang joined us from Ventura County; so we had 7 NSXs on the track. The big surprise was Allen, who has been tinkering with his car all winter. Don't get fooled by his quiet demeanor, he is getting to be a real boy racer and was at the limit of his car on most turns. As usual, Brian had to do change pads at the track. I did stiffen my rear sway bar and on this track I think I like it better that way, less understeer. But it took me two sessions to get the pads embedded, so hauling down to turn 2 with little brake was an experience. I finally got to ride in Kip's car when he went out to heat cycle his new track tires and rotors. That is one well balanced mean machine! To see an NSX handle that way is a joy.

But the real story is, at least four of us got food poisoning from the track lunch :frown:

 

[Andrie Hartanto]

Hrant, let's hear the stories!!!

What kind of lap times Kip pulling?

 

[Hrant]

I will let Kip answer lap times, I didn't see a transponder in his car.

Laguna allowed 35 cars on the track so there was more than usual traffic. What was amazing to me was how Kip could dice/slice in and out at turn in, track out with new tires and the car would stick like glue without the slightest hint of oversteer or getting loose. Surprisingly, the Comptech suspension was not harsh even though he has stiffer springs. He was closing in on slower traffic so fast that he often had to change his lines. Think of getting into 6 only to find a slower car trying to track out ...... The power going through the gears at the front straightaway was great, smooth and linear, enough to put a smile on one's face as it kicked you back into the seat with every shift. And he has Comptech's new short shifter ...... too many goodies to drool on.

It would be curious to see you in that car ..... :wink:

 

[Andrie Hartanto]

Yep,

the Comptech suspension is amazing, eh? I've been telling people, the way to setup a good suspension is to have them comfortable for you to drive. A race car doesn't have to be stiff. The spring has to be at high rate to resist the roll, but the shock should be a good shock that can dampen all the track undulation and spring energy. Lots of the key of getting a good suspension to work is tuning. Professional spend hours to tune suspension for a reason. If professional take hours, imagine how long a joe blow will take? If he is going in the right direction.

 

[92 white 0650]

Re: Kip's times

What kind of lap times Kip pulling?

I tried to smoke him out last year but he just smiles that boyish smile, kicks the dirt and say's "Gosh, I don't know............I'm not in it for the times.........yadee yadeee yadeee....." Makes me wanna knock him upside the head and remind him that "this is us you're talking to."

And when I've had the time to put a watch on him, he's always been giving someone a ride, or in traffic or cooling down for some reason. But I know he's under 1:40 by now, easy.

 

[Hrant]

Re: Kip's times

I agree with the 1:40. I believe Justin and Dave were in mid 1:40s with their spec Miatas and if Justin had to comment about who that red NSX was - as in he is going fast, that should tell you something :wink: