Cars Honda NSX 3.6.5

[Kyuubeey]

Yeah. Also part of the reason they switched to much larger rears and larger split difference later.

Btw the cars are only intended to be driven with SVs. Factory pressures are 33/40, but put 30/32 or something for track. ST and SM are off the rack tires like you would buy IRL, which might be closer together in grip and oversteer more proportionally. The OE tires are more split rearward + they have some scuffing bias which we can't even do in AC.

 

[djtopa]

Didint tried base NSX but IMO to me even R is undrivable.NHF but..like it has no grip on rear end...on SM tyres before recent updates it was hard to get it powerslide and that was biggest problem from the first time I tried it years ago.Now it it oversteers like it has 800PS.Not just oversteers if I shake a wheel on straight rear end is gone...
Didnt drive the real NSX but something is off .I hope others more experienced will tell the same and that will be update.We need good Hondas .Other thing is on this mod I always need to put FFB on around 107 in AC stock cars its around 87 on my setup its weak ...good luck.
Ps:I didnt know this part:" only intended to be driven with SVs."
If its like that why even include other tyres...

 

[Kyuubeey]

Ps:I didnt know this part:" only intended to be driven with SVs."
If its like that why even include other tyres...

I mean, it's not like any car is intended to be driven on anything but the OE tires. It's like putting modern sticky radials on a car that was designed for bias ply. Your results may vary.

The ST and SM are reasonably realistic for their dimensions and compound, and the SVs are tweaked a bit to take into account the characteristics descriptions of the real tires. It probably won't handle "like it should" or "like in the videos" with ST or SM; because it wouldn't on the real car. The exception is newer runs of the "same" tires, specifically corner marked (Because you can't rotate them IRL) and sold as for the NSX, which could be (Still can be?) bought years ago. The "normal" version of the tire won't be the same thing.

Anyway, if you have some data, or footage, or something you wanna substantiate your assumption of the car being dramatically incorrect with, post em here.

 

[djtopa]

Gonna try it more on ST and SV tyres....

 

[Kyuubeey]

Gonna try it more on ST and SV tyres....

Just don't hold the trailbrake as hard/as long and get on the throttle after turn-in. It's mid engined. If you look at pedal cams of Gan-san, he's almost never not on the throttle a little bit at least.

 

[Leonardo Ratafiá]

there's gotta be some typo on the updated files, it really makes no sense how the NSX looses the tail at such low speed

 

[Kyuubeey]

Almost like they developed the NSX-R, then put bigger tires on the rear and made the front spring stronger on the standard car to alleviate that or something.

 

[Kyuubeey]

@kondor999

To reply to your review:

The toe curves are essentially as close as it'll get, within a few hundredths around +-40mm or so (I have curves) *and* the diff *is* fully open on decel. It's fully open on accel too, except there's preload. There isn't even actually a limited slip diff on the early NA1s. Later they added a torsen, which *might* be open on decel, might be equal on decel and accel too. I would guess equal.

What year car did you drive? American NSXs also received 215/245 tires, as opposed to the 205/225's. Did you try the Acura or the Honda?

 

[aphidgod]

Without having dug into it too deeply, I think it's the insanely low front rebound damping that's causing all of the trouble. I'm having a hard time believing it, but Arch says that's what the data says, and we all know how much you guys have been wanting us to change our methods and look at data when we do these cars, so... enjoy your NSXs!

 

[Kyuubeey]

Yeah. Here's the plots for reference. They line up so well with all of the other plots and damping force I've found that I used them directly. Doesn't look like they've gone bad very much; or if they have, they go bad in the exact same way over different amounts of years.

NSX-R was made using the logic from these plots + scaling forces until it produced a reasonable damping ratio and the response on launch and braking compared to video footage was similar. Looks like extremely high front rebound for NSXR, and critical~ damping front rebound for NSX*, which is where it is now. When I get some more time, maybe I'll take another look at it to verify, but I do trust the plots.

*Oh, no, that was the rear. Front is quite low, but hey, that's what the plots give out. I'll verify to footage later.

 

[Avo77]

Arch, you can post all the data you may find but the car behaviour is simply wrong in the last update.

 

[Kyuubeey]

Arch, you can post all the data you may find but the car behaviour is simply wrong in the last update.

I could believe it; I'd design the car differently myself.

So, what's your source?

 

[Avo77]

20 years of vehicles design and testing.

 

[Kyuubeey]

20 years of vehicles design and testing.

Cool. So none at Honda in the 80's I presume.

Well, I'll bite. Assuming that Honda didn't lie about the NSXR roll stiffness ratio and assuming my data on the geometry, spring, sta-bar and aero properties isn't just completely false and the schematics aren't way off either, what is it? Tires? I already put in a bit extra CoF to the rears.

Actually, how *do* you think the car should be, and why?

 

[Avo77]

All cars (no matter if race or mass production) MUST have a positive understeer gradient.

It will kill the driver otherwise (no matter the driving skills).

Just test your implementation on an infinite flat surface and see what happens trying to slowly increase the lateral acceleration even at very low speeds (60km/h).

If you believe that can be realistic, probably you've never driven a car at any speed...

 

[Kyuubeey]

All cars (no matter if race or mass production) MUST have a positive understeer gradient.

It will kill the driver otherwise (no matter the driving skills).

Just test your implementation on an infinite flat surface and see what happens trying to slowly increase the lateral acceleration even at very low speeds (60km/h).

If you believe that can be realistic, probably you've never driven a car at any speed...

Yes, I understand your point, but it's still not helpful at all for the NSX, especially considering there's been a host of production and race cars that can get into a true oversteer situation with minor driver input. AW11 and MY00 S2000 come to mind. Pretty sure it's not *actually* oversteering in steady state though, did you test it yourself? More of a coast thing. I'll check it later when I can, myself.

Anyway, there's almost nothing that can be done apart from breaking the mechanical rules of the system or just putting in more tire grip. I could try more progressive and perhaps longer front stops as I don't have a precise measurement, so it might stop the oversteer situation sooner, as it might IRL. Sure doesn't *look* like it though, pro drivers on BM keep going sideways on corner entry.

There's also a chance I gravely misunderstood the suspension system or something, but considering the R roll stiffness ratio lines up within 1%, I'm not too sure. Far more inclined to believe that every single NA1 NSX damper graph is wrong and the front specifically has gone bad due to age.

 

[Avo77]

Can go into oversteer in transient situations, not at steady 60km/h.
By looking at the data the problem is mainly due to the rear spring stiffness (any other change would make minimal difference with such an imbalance in roll stiffness).

P.S.
I've driven al least five S2000s at any speed and lateral acceleration allowed by the (weak) engine and by the tires. Still alive.

 

[Kyuubeey]

Can go into oversteer in transient situations, not at steady 60km/h.
By looking at the data the problem is mainly due to the rear spring stiffness (any other change would make minimal difference with such an imbalance in roll stiffness).

P.S.
I've driven al least five S2000s at any speed and lateral acceleration allowed by the (weak) engine and by the tires. Still alive.

Yeah, it probably is the main reason coupled with the rebound ratios. The stock car's split is very high, and it kept getting smaller over the years. Also heard something about "excessive drop throttle oversteer", but even then it does *feel* a bit much, even if it's basically exactly the same transient response like on footage. Footage can still be deceiving.

The issue is, why is the the R's roll stiffness split well within the margin if the spring MR or force is off? If we calculate the rear MR differently and end up with 0.700~, the % gets skewed 10%~ potentially, hinting towards much stronger rear sta-bar or bumpstops, which are both out of the ballpark. 2.3's split is 65%~ front and the behavior's not even right.

I *can* believe that my methodology is off, or that Honda's data is backwards, with the stiffness being 45% rear, or 55% front. Gotta take another look at the source itself closer; but it sure does say "front". Some handling characteristics on-power also don't seem to match up completely, but that can be explained by tires or manufacturer trickery as well.

Anyway, treating it as a traditional DWB with LCA/UCA attached strut (Which it isn't), we get an MR of 0.720.

If you do the math:

94873.1141657 / (94873.1141657 + 80406.3849233) = 0.54126760208. With a tiny bumpstop change we'd have 55% front, so this does support the other hypothesis. Only question is; why? Mechanically, it makes little sense. I'll need to calculate the MR with a 3rd method and see if a bumpstop change will bring it in line with 45% rear; if that's the actual value. Or someone could just go and measure it.

On quite a few cars, the current method has produced results within 0.025 of experimental data, so I just rolled with it.

A hypothesis I'm thinking about is also that this roll stiffness % is the ratio of lateral flex, because they talk about stiffening subframe and tower parts; and it's a total coincidence it matches up either way you spin it. Wouldn't be a first for me. Which is why I try to go for a more mechanical approach.

Note how it says roll resistance, not stiffness.

I'll take a look later, but this week it's unlikely I'll find the time.

 

[Kyuubeey]

Quickly doing a recalc and putting in new values gives me 1.3 and 1.6hz for NSX and 2.0 and 2.0hz for NSXR. I can buy that, pretty typical. They were 1.3/1.8 and 2.0/2.3 formerly. I did raise an eyebrow at that, but I've seen weirder.

It's not like the car won't LOO, but steady state should be more understeery with this. There's some hidden benefits like more stroke until the rear hits the bumpstop, so it adds up. But anyway, now I can't implement this. Just be patient, it'll be ok.

 

[spanner76]

2.3 was good, 2.31 is broken. Handling has been messed up after the latest update. I deleted the new version and re-installed the older version.

I have reviewed a lot of Honda NSX videos in the past and the older version reflects how the real world car handles. This new version handles like a car with a solid rear axle.. PLEASE FIX!!!