'floaty' feeling

[swerve2007]

i have experienced a 'floaty feeling' (seems like a vague rear end response) while cornering at a good clip with suspension unloaded (translation- does not happen in hard corners or under acceleration) usually in fast sweepers or decreasing-radius corners. i have read some comments here on prime and, so far, have gathered that it does not depend on sways and shocks but mostly rear-end geometry and bushings.
would you guys enligten me on the issue? is it something i need to live with or can it be 'corrected'? i need to get on the track to really find the limit before i encounter the snap-oversteer.
thx

 

[swerve2007]

anyone?

 

[fourringpilot]

I have the same issue. I guess it was just the way the suspension was set up - easy riding at lower speeds / tighter for hard high speed cornering.
I would also like to understand the dynamics of this.
Is it the progressive rate of the springs?

 

[stuntman]

Try getting into the habit of giving the following information with a description of the problem to better understand where you're coming from:

Wheels (width and Diameter)
Tire (model, width, sidewall)

Suspension:
Dampers
Spring rates (F&R)
Swaybars

Any additional: non compliance beams, chassis bars, etc...

Alignment:
Camber (F&R)
Castor
Toe (F&R)

and any additional useful information.



0.02 :smile:

 

[titaniumdave]

This is corrected with rear beam bushings and rigid toe links. What you are feeling is probably the rubber compressing during loading in and out of corners.

PM if you need parts, I make them...

 

[swerve2007]

Try getting into the habit of giving the following information with a description of the problem to better understand where you're coming from:

Wheels (width and Diameter)
Tire (model, width, sidewall)

Suspension:
Dampers
Spring rates (F&R)
Swaybars

Any additional: non compliance beams, chassis bars, etc...

Alignment:
Camber (F&R)
Castor
Toe (F&R)

and any additional useful information.



0.02 :smile:

car is stock- thats why i did not list suspension mods.
i do have chassis bars and am planning on full zanardi susp install but i would like to sort things out / understand the issue before i add new unknowns into this equation.

ti-dave-
would the rubbers in the rear beam really contribute this much? the issue does definitely originate from the rear.
are the rigid toe-links preventing from camber / toe changes due to compression of the suspension? wouldn't this only work when you load the suspension? camber/toe changes would certainly feel like the issue i am 'seeing'.

just to explain, there is no problem with the components i.e. there is no damage- i am just sensitive to car handling issues, especially when the car is this close to perfection.

 

[titaniumdave]

ti-dave-
would the rubbers in the rear beam really contribute this much? the issue does definitely originate from the rear.
are the rigid toe-links preventing from camber / toe changes due to compression of the suspension? wouldn't this only work when you load the suspension? camber/toe changes would certainly feel like the issue i am 'seeing'.

just to explain, there is no problem with the components i.e. there is no damage- i am just sensitive to car handling issues, especially when the car is this close to perfection.

Yes, what you are experiencing is why people started to make these items. The rear of the NSX has almost '0' bump steer, so the travel of the suspension does not effect the toe on the rear end. Your camber decreases as the suspension compresses, which is a good thing for control. What you are feeling is the rubber bushings allowing the car to move sideways as the lateral load builds. The rear beam bushing and toe link are very close to the same line as the rear axle centerline, this is the direction of lateral force from cornering load. Because the pivot locations are close to the direction of force, they will take most of the load and the rubber will allow these pivot points to deflect, effectively the front lower pivot will act as a fulcrum around which the arm will try to rotate. As the cornering loads increase, there will be dynamic changes in both toe and camber, it is possible for the toe to go from toe in(stock) to toe out which makes the rear end feel like it is wanting to steer to the outside of the corner, while the negative camber is reduced which in turn reduces grip. I believe this is why stock NSX's have 'snap over steer'.

All of these dynamic changes are addressed with beam bushings and rigid toe links, they work as a set to control the rear suspension under hard cornering.

 

[stuntman]

Your camber decreases as the suspension compresses, which is a good thing for control.

Don't you mean, camber increases? -camber gain.

As the cornering loads increase, there will be dynamic changes in both toe and camber, it is possible for the toe to go from toe in(stock) to toe out which makes the rear end feel like it is wanting to steer to the outside of the corner, while the negative camber is reduced which in turn reduces grip. I believe this is why stock NSX's have 'snap over steer'..

Don't you believe the majority is due to the general polar moment of a mid-engine car?

 

[titaniumdave]

Don't you mean, camber increases? -camber gain.

Don't you believe the majority is due to the general polar moment of a mid-engine car?

Camber goes 'more negative' as the suspension compresses. This is a lower number, so, as stated there is a 'decrease' in camber. This is a bit of a semantics issue, but we are saying the same thing.

Yes, polar moment is why we experience the loads on the rear suspension and why these fixes are so effective at controlling the dynamic changes. You have experienced this first hand driving the 'Factor X' racecar which has a full set of mono-ball pivots I made for them.:wink:

Thanks for helping clear up my wording.:redface:

 

[stuntman]

Camber goes 'more negative' as the suspension compresses. This is a lower number, so, as stated there is a 'decrease' in camber. This is a bit of a semantics issue, but we are saying the same thing.

Yes, polar moment is why we experience the loads on the rear suspension and why these fixes are so effective at controlling the dynamic changes. You have experienced this first hand driving the 'Factor X' racecar which has a full set of mono-ball pivots I made for them.:wink:

Thanks for helping clear up my wording.:redface:

There's positive camber (top of the tires sticking out), zero camber (tires straight up), then negative camber (top of the tires lean inward).

We almost always run negative camber in any car, the NSX is no exception. SO when I meant as the suspension compresses, it increases camber: it meant negative camber increases as the suspension compressess. The usual termonology for increase or decrease in camber is relative to negative camber - for almost all racing situations. Even if a racecar has zero camber (fwd cars or solid axle cars) camber loss (now going into positive camber) is still called camber loss.

0.02

Yes I felt it in the FX car, but that has 265/305 r-compounds on it. for a bone stock car (which he still hasn't mentioned what tires he's running -15/16" wheels?) I bet more of it is due to tire wall flex from a big side wall, soft dampers that are worn out combined with soft spring rates than bushing deflection.

But I do have to give my approval of Titaniumdave's products as they are high quality, does what he says they do -monoball provides no bushing 'binding' nor deflection, and he's great to work with.

Again, for a bone stock car, I might look into other areas first (again why its good to state your ALIGNMENT, TIRE SIZES, etc... even if its a stock car).

 

[swerve2007]

thanks for your input, really, i do appreciate it, but to automatically assume that i have mechanical issues that are messing up my handling is a bit 'off', especially if i stated that those are not a factor- i am still learning nsx's idiosynchresis' but that does not mean i do not know/feel what suspension is doing.
btw, stock 2000 has 16/17in wheels and tires are premium.

ti-dave- thanks, i'll pm you about the parts.

thanks all, problem solved, close the subject pls.

 

[stuntman]

thanks for your input, really, i do appreciate it, but to automatically assume that i have mechanical issues that are messing up my handling is a bit 'off', especially if i stated that those are not a factor- just because i am fairly new to nsx and am still learning its idiosynchresis' does not mean i do not know/feel what suspension is doing.
btw, stock 2000 has 16/17in wheels and tires are good.

ti-dave- thanks, i'll pm you about the parts.

thanks all, problem solved, close the subject pls.

Who is assuming that you are having mechanical issues? I havn't read a post that comes to that conclusion...

Tires are good? What model and width?

 

[CL65 Captain]

btw, stock 2000 has 16/17in wheels and tires are premium.

Tires are premium? My Goodyear F1GS3 were "premium" but the sidewalls were soft and gave a nice squirmy ride. Don't get me wrong they had plenty of grip - AFTER they took a set, but the transitions made the car feel sloppy compared to a stiff sidewall tire.

 

[swerve2007]

"...for a bone stock car (which he still hasn't mentioned what tires he's running -15/16" wheels?) I bet more of it is due to tire wall flex from a big side wall, soft dampers that are worn out combined with soft spring rates than bushing deflection."

i wouldn't bet.

 

[stuntman]

anything else?

Their are a few people on this thread who are trying to help you but need a little more specific information to help troubleshoot and point out what might be the cause of what you are feeling.

I have a lot of seat time in numerous NSXs both on the street and on the track with various products. CL65Captain also has a bit of track time under his belt as well.

If you are looking for help to solve possible problems then help us help you. :smile:


so, what size and model tires are you running?

 

[CL65 Captain]

Just change out the Flux Capacitor and be done with it!

 

[stuntman]

"...for a bone stock car (which he still hasn't mentioned what tires he's running -15/16" wheels?) I bet more of it is due to tire wall flex from a big side wall, soft dampers that are worn out combined with soft spring rates than bushing deflection."

i wouldn't bet.

I've tracked 15/16" setup, 16/17", 17/17", 17/18" on many types of tires (NSX-specific), and many more tires on various other cars (which I do for a living). Tires make a HUGE difference in the handling characteristics, stability, and performance of your car (it's the ONLY part of your car that touches the ground) -and is one of the greatest performance factors that determines laptimes.

So tires can make a huge difference and the cause of handling characteristics even with a small side-wall 17 or 18" wheel -due to tire tread design which causes squirm, as well as sidewall or tire carcass stiffness.


I am not quite sure why you are being so evasive with what tires you are running, we are only trying to help...


Far too often people are too eger to give answers before they hear the question. Most people/shops/etc... dont take look at the situation (which the list of things to post when you have a problem -are basic but important) which is very important at understanding where the person is coming from to trouble shoot the problem to find a solution.

 

[swerve2007]

Tires are premium? My Goodyear F1GS3 were "premium" but the sidewalls were soft and gave a nice squirmy ride. Don't get me wrong they had plenty of grip - AFTER they took a set, but the transitions made the car feel sloppy compared to a stiff sidewall tire.

tires are re050's. i am not being evasive but you are trying to pin blame on something that has nothing to do with the issue. it is not a apex-transition problem where the tire flex is a concern. the situation takes place in conditions where both suspension and tires are partially loaded but are already in equilibrium, as stated, in sweeping fast corners etc.

 

[stuntman]

i stated that it is floaty with suspension unloaded in fast sweepers - it is not a cornering transition issue. tires are re050's btw.

Thank you! Both the tire model and more detailed description of the problem you just gave makes a big difference.

RE050A is a good tire that dosn't squirm too much, has a pretty good sidewall and overall is a good tire.

The powersteering equipped cars are a bit lighter than non PS cars, this makes for a much lighter steering effort that responds a lot quicker than non-pS cars. The car is a bit floaty and unsettled on highspeed corners IMO due to the over-assisted steering. Much of this can be reduced by your suspension (so we are in agreement), but through the spring and shock rather than bushing deflection.

I do recommend the monoballs from Ti-dave, but even on a stock 91 NSX, the bushing deflection isnt bad enough to be a problem or his product to be a fix for street driving. If you are feeling this a lot on the street, and from your description, replacing your suspension would solve the problem.


0.02

tires are re050's. i am not being evasive but you are trying to pin blame on something that has nothing to do with the issue. it is not a apex-transition problem where the tire flex is a concern. the situation takes place in conditions where both suspension and tires are partially loaded but are already in equilibrium, as stated, in sweeping fast corners etc.

You edit your posts too much... Not quite sure what "apex-transition" is but yes the tread squirm is pronounced in transitions. I'm also not quite clear about suspension and tires being partially loaded but in equilibrium, can you clarify?

-I still stand by my spring/shock diagnosis.

 

[swerve2007]

"..I'm also not quite clear about suspension and tires being partially loaded but in equilibrium, can you clarify?"

sure, i meant that the side-loading of the car is constant - i.e constant radius sweeping corner where no additional forces are added (like bumps or radius changes) so the suspension and tires have already 'settled'. furthermore there are no steering inputs per say.
the situation occurs at a pretty good clip but not at the limit (close though) and it is aggrevated by taking the foot of the gas but not quite acceleration-off-oversteer.

i don't think my shocks are shot- they perform very well everywhere else and the car only has 40k miles.

 

[stuntman]

"..I'm also not quite clear about suspension and tires being partially loaded but in equilibrium, can you clarify?"

sure, i meant that the side-loading of the car is constant - i.e constant radius sweeping corner where no additional forces are added (like bumps or radius changes) so the suspension and tires have already 'settled'. furthermore there are no steering inputs per say.
the situation occurs at a pretty good clip but not at the limit (close though) and it is aggrevated by taking the foot of the gas but not quite acceleration-off-oversteer.

i don't think my shocks are shot- they perform very well everywhere else and the car only has 40k miles.

Much better info/feedback :smile:

If everything was constant, (speed, steering input, radius, lack of bumps, etc...) the car would do the exact same thing since load is constant (even in regards to bushing deflection). You said but when releasing off the gas, the problem is aggrivated. In a mid-engine car with a 40/60 weight distribution and a big polar moment w/the engien out back does have the car to start to rotate more. You transfer more weight to the front of the car, giving the front grip, unload the rear that's heavy (engine) and it starts to rotate around on you. It's a function of a mid-engine car.

Having tracked many 97+ and 02+ PS-equipped cars (some bone stock as well), the stock suspension, while not shot, is pretty soft and rolls around and exaggerates the problem. Ive driven a brand new 04 and the suspension was very soft and wasn't very confidence inspiring on the track.

IMO for a low-mileage, well taken care of stock car, I still would say its a function of the dynamics of the car, and is exaggerated by the ride height, lack of damping and spring rate of the stock suspension. Again, you suspension may not be shot, but being that soft from the factory with PS does result in the feeling you're describing.

0.02

 

[titaniumdave]

What are alignment numbers? Reducing rear toe out from stock numbers can help with what you are feeling too. This depends on where you are now...

 

[stuntman]

What are alignment numbers? Reducing rear toe out from stock numbers can help with what you are feeling too. This depends on where you are now...

-again, why it's important to post all of that information up front with the problem (For eveyone reading).

titaniumdave - usually the rear of NSXs have toe-IN

 

[swerve2007]

my camber is set at stock settings, which i understand are less aggressive than earlier cars which in turn may also contribute. i do like the even tire-wear now and would be hesitant to change the camber to alleviate an issue that occurs only at fast pace (if i was racing it i would change of course).

i understand the dynamics of nsx and am familiar with the throttle-off-oversteer so thats why i stated that it wasn't really that issue although it is aggrevated by it simply by its nature.
i guess so far the best/closest description was that of ti-dave statement that the rear wants to oversteer when the bushings compress- even under constant throttle.
sure, i will completely agree that lack of shock damping may contribute/cause this problem but how do you explain it happening on smooth surface where susp action is minimized? to me it sounds like the issue is sensitive to side loading only- whatever susp pieces may be affected.

 

[stuntman]

my camber is set at stock settings, which i understand are less aggressive than earlier cars which in turn may also contribute. i do like the even tire-wear now and would be hesitant to change the camber to alleviate an issue that occurs only at fast pace (if i was racing it i would change of course).

i understand the dynamics of nsx and am familiar with the throttle-off-oversteer so thats why i stated that it wasn't really that issue although it is aggrevated by it simply by its nature.
i guess so far the best/closest description was that of ti-dave statement that the rear wants to oversteer when the bushings compress- even under constant throttle.
sure, i will completely agree that lack of shock damping may contribute/cause this problem but how do you explain it happening on smooth surface where susp action is minimized? to me it sounds like the issue is sensitive to side loading only- whatever susp pieces may be affected.

Side load, loading up the suspension in the corner needs to be controled by the spring and shock. It perfectly explains how lack of damping from the stock shocks and a lot of body roll due to the soft springs result in a floaty feeling (floaty as in the title of this thread). Bushing deflection dosn't result in a 'floaty' feeling.

0.02