It's all about mu

[PMPB]

Originally Posted by stugray

If you could get significantly greater than 1.0G in a skidpad test, dont you think a multi-million dollar car could do it?

So based on those numbers, the BRZ is a poor handling car (by today's standards).
(caveat: the above 0.93G skidpad test was done with the well known "crappy" stock tires)

I'm glad you put the caveat, because the tires alone on the Bugatti are worth more than the BRZ.

Some tires display adhesion (like tape). They mold to the surface (conjoin), etc. Not just friction.

[wparsons]

Originally Posted by stugray

• is the Normal force exerted by each surface on the other, directed perpendicular (normal) to the surface.

So when you're hard into a corner and weight has transferred to the outside tires they're not carrying more weight than they would be while at rest?

http://www.caranddriver.com/features...rbitals-page-3

I'm not claiming you can get 3G, but it is definitely possibly to get above 1G without downforce.

This is also a sustained skidpad reading, in a shorter corner you can record much higher forces than you'll pull on a skidpad. You also have to make sure you're comparing apples to apples, some skipads are 300', some are 200' and some are 120'. The same car will pull different numbers on each diameter.

[maloney2]

So when you're hard into a corner and weight has transferred to the outside tires they're not carrying more weight than they would be while at rest?

Yes they are, but the weight has been transferred from the inside wheels so the total normal load remains the same. In general the more load transfer the lower the cornering potential of the vehicle due to the diminishing frictional coefficient of the tires with increased load.

[Gords_zenith]

Maybe someone can post lateral g's using the same tires as a new Corvette aka Michelin pilot super sport stock size and I would guess it would pull significantly better.

[7thgear]

AFAIK the PSS don't come in 17s

[PMPB]

Originally Posted by 7thgear

AFAIK the PSS don't come in 17s

They are actually pretty affordable.

http://www.tirerack.com/tires/tires....SSXL&tab=Sizes

Here is what the FRS can do with meaty AD08's
http://www.edmunds.com/car-reviews/t...rack-test.html

[chrisl]

Originally Posted by stugray

And in Suberman's defense (I know I will regret this).

The BRZ is rated at 0.92Gs on the 300 ft skidpad.

Just beneath the 1988 Vette (0.93Gs) and barely above the 1985 Honda CRX (0.91Gs).
Note: The 2008 Bugatti Veyron gets exactly 1.00G. If you could get significantly greater than 1.0G in a skidpad test, dont you think a multi-million dollar car could do it?

Apparently not - the ZR1 Vette gets 1.1G on a skidpad, and the 991 GT3 gets 1.12, despite the fact that you could easily buy two of each and a nice house for less than the cost of the Veyron...

[7thgear]

Originally Posted by PMPB

They are actually pretty affordable.

http://www.tirerack.com/tires/tires....SSXL&tab=Sizes

Here is what the FRS can do with meaty AD08's
http://www.edmunds.com/car-reviews/t...rack-test.html

ohh that's not so bad

i think i was thinking of some other super fancy, corvette-only tire (that only comes in like 3 sizes)

[stugray]

Originally Posted by wparsons

So when you're hard into a corner and weight has transferred to the outside tires they're not carrying more weight than they would be while at rest?

No they are not really "carrying more weight" ( no tire can "hold more weight" that the total weight of the car).
I agree that there IS a very brief transient downforce on the outside wheel due to the rotational inertia of the car as you "snap into a corner" , but it does not last more than a fraction of a second.
So it does not really come into play over the course of an entire corner.

This is part of the concept of "Mu" that suberman was trying to get across.

When the weight of the car is distributed evenly over 4 wheels and you try to pull the car sideways with a lateral force, you have 4X as much contact patch as you do if only one wheel is in contact with the ground, but each contact patch is only carrying 1/4 the weight.
Since each contact patch has 1/4 the weight, it can sustain 1/4 of the lateral force.
When all of the weight is on one contact patch, that patch can sustain 4X as much lateral force due to the additional down force on that contact patch.

That is the concept of Mu. Regardless of how much contact patch you have or how the weight is distributed, you have the same ability to resist the lateral force. (that is until the non-linear characteristics of tire deformation & stiction come into play)

[krayzie]

Okay then post up the lateral g's for the Subaru BRZ tS they come with 225/40/R18 PSS stock lol! I tried googling it in Japanese but nothing even from the reviews.

[stugray]

Originally Posted by chrisl

Apparently not - the ZR1 Vette gets 1.1G on a skidpad, and the 991 GT3 gets 1.12, despite the fact that you could easily buy two of each and a nice house for less than the cost of the Veyron...

Then that just means that those cars have tires that have a frictional coefficient that is greater than 1.0 OR the results were taken on a skidpad greater than the 300ft version.

When you go up in skidpad radius, the average speed of the vehicle goes up so aerodynamic downforce comes into play.

Another effect I have seen when trying to measure lateral acceleration in cars with data acquisition: A fixed data acq system (like traqmate) has internal accelerometers that can measure acceleration in 3 axes.
I have seen a 62 triumph TR4 register nearly 1.0G "lateral" acceleration.
That is clearly not reasonable in that car, so what is happening is that as the car corners, the body rolls and the "lateral" accelerometer is now getting a component from gravity.
So sometimes the lateral "G-force" numbers are lying a bit.

[Dave-ROR]

Originally Posted by Suberman

Maybe somebody will actually quote a specific refutation from an actual suspension engineer? What an idea? We now apparently have one, or at least a wannabe one, but he still has difficulty reading and writing, and with a Masters degree (don't ask a practicing engineer what he thinks of engineers with masters degrees, just btw, they may suggest only incompetent engineers stay in school longer than they need to ...just sayin'. That's the basis for all those Howard jokes on Big Bang: no PhD AND "just" a Master's degree. All the engineers with only a bachelors degree roll on the floor laughing at that continual running double joke.)

So basically you just insulted someone who continued their education past the bare minimum because you felt threatened by them or something?

Keep it up and your stay will be shorter than you expect it to be.

[7thgear]

rats, the mods are on to him.

our chance for village justice is ruined.

[SkAsphalt]

I like my Master's degree