Thread: Pfadt or Eibach
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Old 01-13-2010, 09:23 AM   #3
IPS Brandon
 
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Drives: 2010 Camaro SS black
Join Date: Aug 2009
Location: Columbus Ohio
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We worked very closely with Pfadt, and I have an exerp from Aaron that I feel does his products a lot of explanation, and maybe if you have questions after this point we can move forward, but this should be a good start on why Pfadt makes the suspension package they do.

"Fast forward to Pfadt making 2010 Camaro suspension. I'd like to throw out my 2 cents on swaybars. Swaybars, more properly called stabilizer bars or anti-roll bars are used to help the handling on any car. Most production cars now come with at least one in place, generally on the front. The Camaro in all of its forms comes with both a front and a rear. The reason that they are used is to limit body roll in the turns. This make the chassis more responsive. The cornering forces go into accelerating the car rather than into body roll. It is important to keep in mind that you can achieve roll stiffness through sway bars, but you can also achieve the same thing through your springs. They both contribute roll stiffness. The reason that the auto manufacturers rely on the sway bars is because they have much less negative consequences in terms of ride quality than achieving a certain level of roll stiffness through just springs. The sway bars are not active in situations where both front or rear wheels are doing the same thing. For example, in the case of a large heave in the road, the sway bars will have no effect on how the cars feels going over it, because both front tires will go over it at the same time and the bar will just rotate in its mounts. If you hit a pothole with one tire the sway bar stiffness will have an effect on the amount of disturbance in the car. The bottom line is that a large amount of roll stiffness is used on 'sporty' street cars because it has a good balance of handling versus ride quality.

For us in the aftermarket, we tend to want to expand on that principle and increase the roll stiffness even more for better handling. The increase in handling comes in three main forms.

1. increase in responsiveness
2. better tire grip due to less roll and an improvement in contact patch
3. improvement in vehicle dynamic balance

The responsiveness comes from a net increase in roll stiffness in the car. That can come from the front or the rear, but generally is done with a combo of both. The better cornering grip comes from reducing the amount of tire contact patch loss that is associated with body roll. In the case of a Macpherson strut car like the Camaro, there is almost no camber recovery from the suspension, so any body roll is tire roll and loss of contact patch. That is why you see such crazy amounts of negative camber dialed into Macpherson strut equipped race cars. They will often run 4 or 5 degrees of negative camber to compensate for the body roll. The rear of a Camaro has reasonable camber recovery, but you still lose camber with body roll so reducing roll is important for maintaining contact patch.

The third and most complicated component is the balance. This manifests itself in oversteer and understeer. Roll stiffness overall is important but the balance of front roll stiffness to rear roll stiffness is of critical importance. To calculate that, you need to know not only the sway bar stiffness but also the stiffness of the springs, because like I described earlier the roll stiffness is generated by both the springs and swaybars. The desired amount of front roll stiffness versus rear roll stiffness is a function of a whole lot of things - tire size, front rear weight distribution, aerodynamic balance, etc... - but it can be calculated. The bottom line is that we make some calculations, compare them to some known information from testing and then test ourselves. The Camaro is well known on these forums to have a large bias towards understeer from the factory. It is also important to note that even with the stock suspension, the majority of the roll stiffness (well over 50%) comes from the sway bars. This means that even with a radical spring change, the roll stiffness balance is going to be hard to shift in a meaningful way. If you want to fix the understeer, you need to start with the sway bars.

At Pfadt we did just that. We came up with a swaybar package that we know adjusts the balance of the Camaro from understeering nightmare to a nimble track machine. I won't get into a lot of meaningless numbers to confuse you, but I can tell you that we added a reasonably large amount of rear roll stiffness to do this. We also added some front stiffness, but the rear is the key. You can see that by looking at the diameters of our bars. An interesting note on that, you will notice that our rear bar is 35mm in diameter. That seems huge, especially in comparison to the front at 26mm. That is a function of the differing motion ratios of the front and rear sway bars. The roll stiffness imparted by each is very similar, but the rear bar hooks to the control arm very far inboard and therefore is subject to a lot of leverage (ie Motion Ratio). The front bar on the other hand hooks directly to the strut and is very close to a Motion Ratio of 1 which means that it is more effective and can be smaller and achieve the same roll stiffness for the car.

By getting this basic balance in place, we can than put on springs of a wide range and the car will still keep it's inherent balance. We can then specify our springs to meet the needs of the customer. A dedicated track car is going to be able to stand a lot more spring rate than a dual purpose car or even a street only car. We also put some adjustment in our swaybars to allow the end user to tune for different tire combinations, track conditions and driving styles.

Our bars increase overall roll stiffness to help response and contact patch, but most importantly they impart a handling balance to the Camaro that it lacks from the factory. I could tell you how to calculate sway bar rates and roll stiffnesses, but that does not really mean anything on it's own. What matters is that we have the capability to do the analysis and then put our products on the track to test them so that you have a handling package that will take whatever you throw at it."

If you like as well, PM me for current pricing on their products for Camaro5 members.

Regards
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