Sway Bars. Myths, Knowledge, Understanding

[55Designs]

Dont forget to add why the Camaros suspenion design is flawed in certain areas that can be fixed with bars and various adjustment parameters with them to dial in. sway bars are usually used as the final stage of suspension tuning. So if you buy springs and bars and install in one shot the owner may not know the variance of the changes made. I tried my bars with stock springs/shocks first.

[PoleCat2SSRS2010]

Also, just wondering. Please respond if this is relevant. How are the factory sway bars removed? especially the front. Seems like to get it to clear the steering rack has to be unbolted and the harmonic balancer has to be removed....to avoid having to unbolt and raise the engine. I tried for about two hours to figure it out and did not succeed. My apologies but I sit with a majority that are not in posession of a GM service manual...for now.

[Aaron Pfadt]

Mike has got a pretty good idea here.

Let me introduce myself in case you do not know me. I'm Aaron Pfadt, the owner and chief engineer of Pfadt Race Engineering. I got my engineering degree from Rochester Institute of Technology and then started my career working at GM Powertrain in Detroit. I worked there for 5 years and then went to Chrysler (then DaimlerChrysler ) and eventually left there to start my own suspension company. I had been road racing for 10 years or so and decided to put my knowledge and love of cars into my own business.

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.

-Aaron

[rodimus prime]

Originally Posted by PoleCat2SSRS2010

Also, just wondering. Please respond if this is relevant. How are the factory sway bars removed? especially the front. Seems like to get it to clear the steering rack has to be unbolted and the harmonic balancer has to be removed....to avoid having to unbolt and raise the engine. I tried for about two hours to figure it out and did not succeed. My apologies but I sit with a majority that are not in posession of a GM service manual...for now.

Bro you just loosen the two motor mount nuts to jack up the engine to get the bar out. It takes all of 1 minute to do. No need to remove the steering rack or any other parts.

[hrpiii]

Originally Posted by dms

what I will do is to present 2 formulas for determining sway bar strength, discuss the 6 areas that determine overall structural strength. Then discuss relationships between front and rear bars. I will take data that is found on the internet, and make the calculations and compare them to all.

Will that work?

mike
dms

knowledge is power.. and we want more power I want to learn as much as I can. As we all do... preach away!!

[jeffny09]

Originally Posted by rodimus prime

Bro you just loosen the two motor mount nuts to jack up the engine to get the bar out. It takes all of 1 minute to do. No need to remove the steering rack or any other parts.

sounds like i cant do this on my own lol

[Aaron Pfadt]

Originally Posted by jeffny09

sounds like i cant do this on my own lol

I've never lifted the engine to pull a front bar. It's a little tight on a V8, buy you can squeeze it past everything. I always take the bar out the passenger side.

-Aaron

[Michael_Js]

Well, I didn't remove any mounts or raise the engine. I did, however, remove the passenger front wheel - remove & install through the passenger side as stated above. It had to be turned once in each direction to get the OEM front sway bar out. I must say, it was not easy and I almost gave up. I did get the Pdaft front sway bar in easily after that - after putting it in upside down since the logo was on upside down

Good luck!

[busaboy]

Mike, I think you should do a long version as there will be a large number of questions that will probably be covered that a shorter version will not catch.

[CamaroSpike23]

mike, throw it up. we can always use more info!

[Info@PeddersUSA.com]

she is up.

http://www.camaro5.com/forums/showthread.php?t=52392

mike
dms