Science of Speed Sways

[integrals]

Just curious on others input on this set of sways.

I currently have them installed on my car with the front in the middle setting and the rear in the softer setting.

Car is running KwV3's with 235 / 275 F/R tires (NT05). I have the Kw's setup as recommended by KW minus the rebound which is set 2 clicks tighter than the KW recommendations for street use as this car primarily see's track time.

The car is absolutely fantastic in larger sweepers and medium to high speed turning, but at lower speed say, 50mph and slower turns such as carousels, the car seems to push continuously. I have to dramatically reduce my entry speeds on this type of turn.

My brain is telling me to put the front sway in the softest settings and try that out.

Does anyone have any experience with these sways and this tire spread?

(billy) lol

 

[docjohn]

you could put the front bar outer hole and rear inner also soften the rebound on the front...that said the incremantal increase in stifness of the swaybars from hole to hole is small and should not really make a large difference.

 

[CL65 Captain]

NSXs push at slow speed. They just do. If you change the sway or dampening then you are compromising the high speed handling. So tune for the overall balance of the car. If you are really happy how it's handling for 80% of the track, then it doesn't make sense to try and reconfig for one slow corner.

Try coming in much, much hotter and trail braking or breathing on the gas to transfer weight to the front. But be ready to correct and fast because it won't be understeering anymore. :biggrin:

Here is an example at Mid Ohio, those that have driven it will understand. The Keyhole is a 180 deg slow corner. The second half of it falls away and leads to the back straight. If you take it at a constant speed, the car pushes like a pig on the second half and you can't get back on the gas until you are at track out and heading down the straight. I have learned that if I come around the corner faster and soon as the track starts falling away and the car begins to push if I breath on the throttle the push reduces.... the weight is being transfered to the front. However, it still understeers here and I have to wait until I know that I have the turn made before getting back on the throttle.

However, if I come into the keyhole really, really hot and the car starts to push bad, I abruptly get off the gas, the back starts to slide and the nose rotates in towards the apex, and then I counter steer just a bit and get right back on the gas hard, the slide stops, the car is pointing to the apex and I am pushing (understeering) right to track out while hard on the gas. But the key is that I got the car to rotate towards the apex.

Here is a video of turn 7 at Putnam Park. The car will push here if you brake and turn in and drive it like normal. However as you can see in the video, I go in hot, slide the car and keep going. No understeer here.

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[ScienceofSpeed]

The 235/275 split is a really nice balanced setup for the NSX. You may want to experiment with a couple things. You can increase the rear sway bar's stiffness incrementally. It would also help to check your front tire's heat spread to see if adjusting your front camber would help.

If you're talking about PIR, I noticed improved exit speed in the carousel if I heavily trail braked into the first part of the corner, then lightly tapped the brakes to get the rear to rotate in the second part of the corner.

take care,
-- Chris

 

[Ponyboy]

Sticking corner entry, IMHO, is the last frontier of track driving. It's correct with the NSX, slow speed corners inherently produce some level of understeer and the best way, again IMHO, to mitigate that characteristic is trail braking via left foot braking.

I haven't been on track w/ any regularity lately but if you want to get your car to pivot: trail brake (even w/o left foot braking) and focus on managing the tail end through throttle(cuz it'll start rotating).

 

[CL65 Captain]

Sticking corner entry, IMHO, is the last frontier of track driving. It's correct with the NSX, slow speed corners inherently produce some level of understeer and the best way, again IMHO, to mitigate that characteristic is trail braking via left foot braking.

I haven't been on track w/ any regularity lately but if you want to get your car to pivot: trail brake (even w/o left foot braking) and focus on managing the tail end through throttle(cuz it'll start rotating).

I can't left foot brake in the NSX. The gas and brake are too close together for me and can't fit both feet side by side comfortably. Great for heal and toe, not so great for left foot braking. :redface:

If you want to completely master trail braking.... a miata will do it for ya. Overdrive those things into the corner and brake hard and late, trail brake to rotate it because god knows they have don't have any torque. Or you can practice with Grandma's 1997 Camry. :biggrin: I'm telling you, I learned more in two days with the Camry than I ever did with the NSX. I drove that thing 11/10ths and practiced every trick in the book to get that thing around the track and managed to piss off a dozen Porsche novices who had to keep pointing by Grandma's car.

 

[TURBO2GO]

I drove that thing 11/10ths and practiced every trick in the book to get that thing around the track

I'm sure grandma would be thrilled to know this... 11/10ths... lol

 

[CL65 Captain]

I'm sure grandma would be thrilled to know this... 11/10ths... lol

Runs in the family. Grandma (91 years old) drives at 11/10ths too and ran over the neighbor's mailbox which is why we took the car away and I inherited a 1997 Camry with 14,000 miles. Oh, and for the record.... it hit 116 mph on the back straight at Mid Ohio.

 

[stuntman]

Integrals (OP): you did not list your tire pressure, alignment (camber, toe, rake (front ride height relative to rear when measured at the front and back jacking points on the frame rail), as well as any aero modifications.

Right off the bat (without knowing the above - not good to throw our reccomendations without knowing more) to reduce understeer you could add rake to the car (front lower relative to rear), add more front camber, soften the front swaybar, stiffen the rear swaybar, soften front rebound, increase rear rebound, or change tire pressures. Softening front rebound and/or front swaybar will reduce the response (make more lazy)

NSXs push at slow speed. They just do. If you change the sway or dampening then you are compromising the high speed handling. So tune for the overall balance of the car. If you are really happy how it's handling for 80% of the track, then it doesn't make sense to try and reconfig for one slow corner.

I respectfully don't agree with this blanket statement. They don't "just" push at low speed. Often this is due to the commonly taught driving style of making sure you're on throttle before giving the car any steering input. In this case - yes the NSX probably (like most cars) would understeer because all the weight/grip is on the back of the car. Changing the swaybars or damping dosn't necessarily compromise the handling at high speed.

Try coming in much, much hotter and trail braking or breathing off the gas to transfer weight to the front. But be ready to correct and fast because it won't be understeering anymore. :biggrin:

Fixed it for you and I agree with this

 

[CL65 Captain]

Integrals (OP): you did not list your tire pressure, alignment (camber, toe, rake (front ride height relative to rear when measured at the front and back jacking points on the frame rail), as well as any aero modifications.

Right off the bat (without knowing the above - not good to throw our reccomendations without knowing more) to reduce understeer you could add rake to the car (front lower relative to rear), add more front camber, soften the front swaybar, stiffen the rear swaybar, soften front rebound, increase rear rebound, or change tire pressures. Softening front rebound and/or front swaybar will reduce the response (make more lazy)
I respectfully don't agree with this blanket statement. They don't "just" push at low speed. Often this is due to the commonly taught driving style of making sure you're on throttle before giving the car any steering input. In this case - yes the NSX probably (like most cars) would understeer because all the weight/grip is on the back of the car. Changing the swaybars or damping dosn't necessarily compromise the handling at high speed.

Fixed it for you and I agree with this

I was trying to say breathing on the gas, as in lifting... but your right breathing "off" is more clear as to what to do.

My point was not to go chasing one slow speed corner with the setup when he's happy with the way it is handling the rest of the course. I have yet to meet a novice that didn't want to change the setup or buy this or that rather than learning to drive the car. :smile:

If I could I would make every student start in a low hp, stock rear wheel drive car (ie Miata or equivalent) and learn to drive the piss out of it and then move up to their car. I think that would make them a much better driver. Unfortunately, it doesn't work that way in HPDEs.

 

[integrals]

Thanks for your input Chris and Billy among others! All has been noted!

Tires were at 36psi HOT all around, front camber is 1.5 degrees and rear is 2.0 degrees. The car is lowered evenly (not biased front or rear).

Toe is 1/16th out in front, and 1/16th in on rear

The car is AERO stock.

Chris I think you are familiar with the turn I speak of in the carousel.

I am tempted to stiffen up the rear ever so slightly, and I do have the REBOUND stiffer than the KW recommendation by 2 all around so considering a reduction of rebound response in the front is a possibility.

Thanks for getting the brain thinking more!

 

[Ty B]

Hot Tires is good, but how about 3 temp readings across the tires. That would be AWSOME, and give you a better idea how your car is using your tires as it is adjusted right now.

 

[YellowHaze]

Wow! Great thread with interesting input from our track experts and expert race guy- Billy. Can't get enough of high quality short videos of how to properly navigate a race course in an NSX. Good stuff!

 

[integrals]

Hot Tires is good, but how about 3 temp readings across the tires. That would be AWSOME, and give you a better idea how your car is using your tires as it is adjusted right now.

This is one thing I have failed to do. Purchasing a Tire Pyrometer is next on the list.

Based on WEAR patterns, the rear seems to be overworking (tires are wearing about twice as fast but evenly).

I know this is irrelevant but was a curious observation.

I have another track day this weekend, i'll post up more information and hopefully some improvements!

 

[docjohn]

besides allowing you to fine tune tire pressures a good pyrometer can alert you to changes in alignment.I had a loose/worn front suspension bushing that was allowing my camber to heat the outside tire as the season progressed,all other things being equal.

 

[CL65 Captain]

Based on WEAR patterns, the rear seems to be overworking (tires are wearing about twice as fast but evenly).

Rears are not overworked, they normally wear twice as fast because 60% of the weight is back there (amongst other reasons).

 

[asylum]

Your cambers are perhaps a little bit to low, especially at the front. The (even) wear of the tires will tell you if you need more. You can also play with the stiffness of the sways and the coilovers.

Anyway, if you want to glean all the tenth of seconds you can, you will have to TAIL BRAKE and do it perfectly. That means knowing perfectly all the brake points of the track, the perfect pressure to apply, the exact apex point of each turns, ... That means a never ending trial :biggrin:

In a perfect world, you should never have a constant speed during your turn. That would mean you braked to early and have to wait the apex to accelerate. You should brake very hard, release pressure when engaging the turn, release it more and more. Not to much pressure because you will either decelerate to much or lose rear grip (here you will forget about saying "the NSX tend to understeer", you will realise how the front wheels are on rails !!!). Not to less pressure because you won't be able to catch the apex. When you reach the apex, the real ideal apex corresponding to your NSX settings (this apex is often farther than what we think when debuting with the NSX that has most weight at the rear - remember to sacrifice corner entry to gain it back when going out of it), you should be able to accelerate immediately almost full gas. If you have to wait more than 1 (perhaps 2) second before flooring it (to avoid missing the corner exit because of understeer - yes, here or at constant speed you will feel understeer), that means that your apex was not far enough in the curve.

Try, try, try and try again ! Even on the track I know best, I am still not able to do this perfectly.

 

[integrals]

Im stoked for this weekend, more stuff to try!

 

[integrals]

Great News!

I tightened up the REAR sway bar ever so slightly.

I now am able to enter as I always have into a turn but am able to get on the power MUCH earlier and exit speeds have greatly increased.

After this weekends two day track event, I noticed finally that the rear tires are wearing more on the inside than outside and the fronts are starting to show an accelerated wear compared to before.

Again not confirmed with a pyrometer but the small change seems to have helped immensely.