Arnie... I realize that the term “handling” is subjective, but wondering if you have an opinion as to why the handling is better with the spacers. Do you think it is because…

New (better?) tires

New (better?) wheels

A wider stance

Or a combination of any, or all of the above

--Spike

 

agreed more then this guy ever will.

 

Haven't changed my tires, still on the WinterSpots. It's the wider stance. The car feels more planted around curves now, more stout.

 

^^ Thanks for the reply. I was guessing, but thought that it was probably the wider stance. I had the opportunity to drive a Z with wider offsets, and it did feel better (actually much better). I'm going to start looking at aftermarket wheels (and not for esthetics, but for handling).

--Spike

 

That is a dumb reply. If the spacers aren't rotating with the wheel what the hell would they be doing? Staying stationary? I don't think so.

The spacers WILL be rotating with the wheel, just as the brake rotors will be. Any mass gained will be too close to the axis of rotation to notice any difference but it is still adding rotating mass.

A wheel of a vehicle both rotates and moves with translation (center of gravity moves with the speed of the vehicle) . It's kinetic energy is a sum of translational and rotational kinetic energy (you can imagine accelerating the wheel in two phases: first you accelerate it's axis, then rotate it), so it is obviously greater than it would be without rotation.

If the speed of the vehicle is v, then most points of the wheel rotate aroud wheel's axis with slower speed than v. So if you transfer a mass m from wheel to fixed mass of the vehicle, the decrease of kinetic energy would be less than m*v^2/2.
Exact value depends on weight distribution of the wheel:

Formula for rotational kinetic energy is: E=J*omega^2/2, where

J(moment of inertia)=Integral (r^2*dm)

In case of a ring (all mass at maximum radious) J would be m*R^2, which gives rotational energy equal to m*v^2/2 (v=omega*R). In case of a uniform cylinder J is m*R^2/2, which gives half less rotational energy.

I don't want to make your head explode but read up on these:

http://en.wikipedia.org/wiki/Rotational_inertia

http://en.wikipedia.org/wiki/List_of_moments_of_inertia

 

Definition of mass:

Mass is a fundamental concept in chemistry, roughly corresponding to the intuitive idea of "how much matter there is in an object". Mass is a central concept of classical mechanics and related subjects, and there are several definitions of mass within the framework of relativistic kinematics. In the theory of relativity, the quantity invariant mass, which in concept is close to the classical idea of mass, does not vary between single observers in different reference frames.

In everyday usage, mass is more commonly referred to as weight, but in physics and engineering, weight means the strength of the gravitational pull on the object; that is, how heavy it is, measured in units of force. In everyday situations, the weight of an object is proportional to its mass, which usually makes it unproblematic to use the same word for both concepts. However, the distinction between mass and weight becomes important:

-for measurements with a precision better than a few percent, due to slight differences in the strength of the Earth's gravitational field at different places
-for places far from the surface of the Earth, such as in space or on other planets

 

That statement is not a direct comparison (i.e., your example is not valid) if you are comparing adding weight to the axles vs. adding weight to the cargo area, and suggest the two are identical.

--Spike

 

Correct Spike. For those interested in facts:

"Sprung" weight is a term used to describe the parts of an automobile that are supported by the front and rear springs. They suspend the vehicle's frame, body, engine, and the power train above the wheels. These are quite heavy assemblies.

The "unsprung" weight includes wheels and tires, brake assemblies, the rear axle assembly, and other structural members not supported by the springs.

 

I took that into account. The small bag of groceries would be much heavier than light aluminum wheel spacers that have a very small diameter (thus extremely little rotational mass). If your wheels are wider, to make up for the spacers, they would be MUCH heavier than the spacers, in relation.

 

Thanks for the google "cut and paste" . Bottom line: adding a 2 lb spacer to the outside of your rotor is NOT going to do anything significant in terms of horse power.

 

WOW i didn't know that people would get so passionate and start bashing each other over my question. I think some people on here need to relax and not take things so seriously. Isn't the whole point of this website to inform Z owners and not bash them every chance they ask what you may think is a dumb question???

 

Arguing that a 2 pound spacer is going to in any-way-shape-or-form contribute to power loss is at the VERY bottom of the list of factors that will contribute to power loss.

Air temperature, density altitude, gas octane, tune, and even tire pressure will have a greater influence on your power loss or gain.

We just don't need people (especially ones that contribute nothing to this site) spreading B.S. that adding spacers will effect the hp of your car.

 

I just asked a question man, I wasn't spreading false information. And if 2lbs isn't that important, why are people spending thousands on light weight rims?? Oh and the comment on not contributing anything to this site is a bit childish. I guess I'll just have to settle with contributing to society as a future doctor and not on a car forum. Oh and why is there so much hate floating around this forum, shouldn't everyone at least kinda get along since we all share a common interest??

 

haha Sorry I should have explained myself better ... that wasn't directed at you at all.

 

...im still lost as to how he thought adding wieght would reduce power? I can jam half the fat chicks from Flavor of Love in your Z and its still gonna make 300 ish horsepower. And your adding 150+ lbs each time u get in, do you think that reduces your cars power somehow?

I'm guessing hes thinking wieght would make him slower, but seriously, its like what, 3 lbs, i can hold in a poop and add 3 lbs, its not going to effect your car any more than turning on your lights and the photons shooting out from the bulbs push your car backwards (they do BTW, just not signaficantly).

 

Well If you're tracking your car, adding 150 lbs will reduce your ET a little.

The word of thumb is for every 100 lbs added you subtract a tenth of a second.

 

100lbs, yes, not three. And that still doesnt add any 'power', you still make 300 HP with -300 pounds or +5000,

 

I never said it would, in one of my posts I stated it is too close to the center of rotation to not notice any difference BUT it is still adding rotating mass. Bottom line.

 

And you're telling me that I'm spreading BS. What would the spacer be doing then if it's not rotating with the wheel? You must explain.

 

Yes it's rotating, I will give that I was wrong. I was not thinking straight when I posted that last night. But in the great scheme of "rotational mass" it's very very negligible.