Beware
#31
08-26-2008, 09:53 PM
Frankly, I am aghast at your ignorance of the aftermarket. There are many aftermarket companies who meet or exceed OEM standards for quality and safety. They passionately respond to the wishes of enthusiast consumers who want to personalize and and enhance the performance of their vehicles. Sometimes. these desires require compromises to accomplish. Then, whiners complain about these compromises and suddenly you want to condemn the whole aftermarket. Why not ask for credible test standards?
Why not hold companies accountable.
In my opinion, you are the poster child for "throwing the baby out with the bath water".
Why on earth are you even a member of this forum?
Why not hold companies accountable.
In my opinion, you are the poster child for "throwing the baby out with the bath water".
Why on earth are you even a member of this forum?
#35
08-27-2008, 05:31 PM
[quote=Forgedwheeler;2013623]Centripetal force would cause the water to move towards the center of the wheel. It is centrifugal force that forces the water into the rim trough and holds it there.[/quote
I stand corrected.
(I looked it up
[edit] Nonuniform circular motion
See also: Circular motion and Non-uniform circular motion
Figure 5: Velocity and acceleration for nonuniform circular motion: the velocity vector is tangential to the orbit, but the acceleration vector is not radially inward because of its tangential component aθ that increases the rate of rotation: dω / dt = | aθ | / R.
As a generalization of the uniform circular motion case, suppose the angular rate of rotation is not constant. The acceleration now has a tangential component, as shown in Figure 5. This case is used to demonstrate a derivation strategy based upon a polar coordinate system.
Let r(t) be a vector that describes the position of a point mass as a function of time. Since we are assuming circular motion, let r(t) = R·ur, where R is a constant (the radius of the circle) and ur is the unit vector pointing from the origin to the point mass. The direction of ur is described by θ, the angle between the x-axis and the unit vector, measured counterclockwise from the x-axis. The other unit vector for polar coordinates, uθ is perpendicular to ur and points in the direction of increasing θ. These polar unit vectors can be expressed in terms of Cartesian unit vectors in the x and y directions, denoted i and j respectively:
ur = cos(θ) i + sin(θ) j and
uθ = −sin(θ) i + cos(θ) j. Note: unlike the Cartesian unit vectors i and j, which are constant, in polar coordinates the direction of the unit vectors ur and uθ depend on θ, and so in general have non-zero time derivatives.
We differentiate to find velocity:
where ω is the angular velocity dθ/dt.
This result for the velocity matches expectations that the velocity should be directed tangential to the circle, and that the magnitude of the velocity should be ωR. Differentiating again, and noting that
we find that the acceleration, a is:
Thus, the radial and tangential components of the acceleration are:
and 
where |v| = Rω is the magnitude of the velocity (the speed).
These equations express mathematically that, in the case of an object that moves along a circular path with a changing speed, the acceleration of the body may be decomposed into a perpendicular component that changes the direction of motion (the centripetal acceleration), and a parallel, or tangential component, that changes the speed.
I stand corrected.
(I looked it up
[edit] Nonuniform circular motion
See also: Circular motion and Non-uniform circular motion
Figure 5: Velocity and acceleration for nonuniform circular motion: the velocity vector is tangential to the orbit, but the acceleration vector is not radially inward because of its tangential component aθ that increases the rate of rotation: dω / dt = | aθ | / R.
As a generalization of the uniform circular motion case, suppose the angular rate of rotation is not constant. The acceleration now has a tangential component, as shown in Figure 5. This case is used to demonstrate a derivation strategy based upon a polar coordinate system.
Let r(t) be a vector that describes the position of a point mass as a function of time. Since we are assuming circular motion, let r(t) = R·ur, where R is a constant (the radius of the circle) and ur is the unit vector pointing from the origin to the point mass. The direction of ur is described by θ, the angle between the x-axis and the unit vector, measured counterclockwise from the x-axis. The other unit vector for polar coordinates, uθ is perpendicular to ur and points in the direction of increasing θ. These polar unit vectors can be expressed in terms of Cartesian unit vectors in the x and y directions, denoted i and j respectively:
ur = cos(θ) i + sin(θ) j and
uθ = −sin(θ) i + cos(θ) j. Note: unlike the Cartesian unit vectors i and j, which are constant, in polar coordinates the direction of the unit vectors ur and uθ depend on θ, and so in general have non-zero time derivatives.
We differentiate to find velocity:
where ω is the angular velocity dθ/dt.This result for the velocity matches expectations that the velocity should be directed tangential to the circle, and that the magnitude of the velocity should be ωR. Differentiating again, and noting that
we find that the acceleration, a is: Thus, the radial and tangential components of the acceleration are: and where |v| = Rω is the magnitude of the velocity (the speed).These equations express mathematically that, in the case of an object that moves along a circular path with a changing speed, the acceleration of the body may be decomposed into a perpendicular component that changes the direction of motion (the centripetal acceleration), and a parallel, or tangential component, that changes the speed.
#39
08-27-2008, 06:14 PM
yeah, we just steal them...
the water retention problem of reverse lip wheels on Porsches has been pretty well documented...If you want the look stay out of the rain or get the evacuators....
the water retention problem of reverse lip wheels on Porsches has been pretty well documented...If you want the look stay out of the rain or get the evacuators....
#40
08-27-2008, 08:31 PM
Forgedwheeler,
I understand your position. You may work or own a company that makes aftermarket wheels named Advanced Metalforming Technology located in California. It is natural to insult people that attack the aftermarket wheel market.
Why companies that make aftermarket wheels don’t work harder to develop products that are safer? Why not to test their products before they go to the market? If this is a well-known problem why aftermarket wheel companies keep making and selling those wheels? If someone dies in a car accident because of a problem with the wheel there is no way a company can repair the damage done.
HRE make very expensive wheels. They have one of the highest reputations in the market. Based on QKNUFF comment HRE knows about this problem. If this is happening with one of the best aftermarket wheels company then image what could happen if you buy wheels from someone with less reputation.
I’m quoting what QKNUFF said :“QKNUFF: HRE has been aware of this for years, and there was a huge thread on the E46 forum "rain problem" with dozens of posts with similar stories”
How do you know who makes reliable wheels and who doesn't?
Who test those wheels and who rank those wheels?
Who rank companies that make those wheels in terms of safety?
What type of tests are done in the aftermarket wheel that can provide confidence to any buyer?
What are the standards that you guys use to decide that wheel A is safe and wheels B is not safe?
I guess Porsche try to answer these questions before deciding what wheels to put in our cars.
Best Regards
I understand your position. You may work or own a company that makes aftermarket wheels named Advanced Metalforming Technology located in California. It is natural to insult people that attack the aftermarket wheel market.
Why companies that make aftermarket wheels don’t work harder to develop products that are safer? Why not to test their products before they go to the market? If this is a well-known problem why aftermarket wheel companies keep making and selling those wheels? If someone dies in a car accident because of a problem with the wheel there is no way a company can repair the damage done.
HRE make very expensive wheels. They have one of the highest reputations in the market. Based on QKNUFF comment HRE knows about this problem. If this is happening with one of the best aftermarket wheels company then image what could happen if you buy wheels from someone with less reputation.
I’m quoting what QKNUFF said :“QKNUFF: HRE has been aware of this for years, and there was a huge thread on the E46 forum "rain problem" with dozens of posts with similar stories”
How do you know who makes reliable wheels and who doesn't?
Who test those wheels and who rank those wheels?
Who rank companies that make those wheels in terms of safety?
What type of tests are done in the aftermarket wheel that can provide confidence to any buyer?
What are the standards that you guys use to decide that wheel A is safe and wheels B is not safe?
I guess Porsche try to answer these questions before deciding what wheels to put in our cars.
Best Regards
#41
08-27-2008, 09:49 PM
If the company is knowingly selling a defective product how do they, therefore, differ from, as you say, "someone with less reputation"?
#42
08-28-2008, 02:02 PM
You make some great points. I have long been an advocate of third party testing and overall accountability by manufacturers.
Most wheel companies know what constitutes a safe wheel. Some are very diligent at testing, some not. Some don't have a clue.
My point was that vibration caused by water retention is common to most three-piece wheels. It is a design limitation created by WIDESPREAD CONSUMER DEMAND, not by the wheel companies.
It is, itself, not a safety concern. It does not hurt the car, the wheel, or cause a loss of control. It is annoying. But owning these wheels is a choice.
Simple due-diligence by the consumer will make him aware of these limitations, as well as the MANY alternatives.
I did respond harshly to your suggestion that all aftermarket wheels are junk and that we should hit people over the head with them.
For the hundredth time, do your homework, choose something you like, and ask for the test data.
Caveat Emptor!
Most wheel companies know what constitutes a safe wheel. Some are very diligent at testing, some not. Some don't have a clue.
My point was that vibration caused by water retention is common to most three-piece wheels. It is a design limitation created by WIDESPREAD CONSUMER DEMAND, not by the wheel companies.
It is, itself, not a safety concern. It does not hurt the car, the wheel, or cause a loss of control. It is annoying. But owning these wheels is a choice.
Simple due-diligence by the consumer will make him aware of these limitations, as well as the MANY alternatives.
I did respond harshly to your suggestion that all aftermarket wheels are junk and that we should hit people over the head with them.
For the hundredth time, do your homework, choose something you like, and ask for the test data.
Caveat Emptor!
Forgedwheeler,
I understand your position. You may work or own a company that makes aftermarket wheels named Advanced Metalforming Technology located in California. It is natural to insult people that attack the aftermarket wheel market.
Why companies that make aftermarket wheels don’t work harder to develop products that are safer? Why not to test their products before they go to the market? If this is a well-known problem why aftermarket wheel companies keep making and selling those wheels? If someone dies in a car accident because of a problem with the wheel there is no way a company can repair the damage done.
HRE make very expensive wheels. They have one of the highest reputations in the market. Based on QKNUFF comment HRE knows about this problem. If this is happening with one of the best aftermarket wheels company then image what could happen if you buy wheels from someone with less reputation.
I’m quoting what QKNUFF said :“QKNUFF: HRE has been aware of this for years, and there was a huge thread on the E46 forum "rain problem" with dozens of posts with similar stories”
How do you know who makes reliable wheels and who doesn't?
Who test those wheels and who rank those wheels?
Who rank companies that make those wheels in terms of safety?
What type of tests are done in the aftermarket wheel that can provide confidence to any buyer?
What are the standards that you guys use to decide that wheel A is safe and wheels B is not safe?
I guess Porsche try to answer these questions before deciding what wheels to put in our cars.
Best Regards
I understand your position. You may work or own a company that makes aftermarket wheels named Advanced Metalforming Technology located in California. It is natural to insult people that attack the aftermarket wheel market.
Why companies that make aftermarket wheels don’t work harder to develop products that are safer? Why not to test their products before they go to the market? If this is a well-known problem why aftermarket wheel companies keep making and selling those wheels? If someone dies in a car accident because of a problem with the wheel there is no way a company can repair the damage done.
HRE make very expensive wheels. They have one of the highest reputations in the market. Based on QKNUFF comment HRE knows about this problem. If this is happening with one of the best aftermarket wheels company then image what could happen if you buy wheels from someone with less reputation.
I’m quoting what QKNUFF said :“QKNUFF: HRE has been aware of this for years, and there was a huge thread on the E46 forum "rain problem" with dozens of posts with similar stories”
How do you know who makes reliable wheels and who doesn't?
Who test those wheels and who rank those wheels?
Who rank companies that make those wheels in terms of safety?
What type of tests are done in the aftermarket wheel that can provide confidence to any buyer?
What are the standards that you guys use to decide that wheel A is safe and wheels B is not safe?
I guess Porsche try to answer these questions before deciding what wheels to put in our cars.
Best Regards
#43
08-28-2008, 02:55 PM
It is amazing the lack of knowledge out there. To the original poster, I would be upset with the people that sold you the wheel for not informing you of the known issues with reverse step lips on wheels, not with the manufacturer.
