Anyone using AFE sways?

[Burkey]

I did a search and couldn't find much...
Just wondering if anyone's actually using these?
The ultra-chunky rear sway bar has me thinking about how it might influence the cars balance away from understeer a little. Or maybe a lot?
Anyone?

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[BlownStang15]

I use them. The bars are hollow for weight reduction, so apples ain't apples when comparing them to some other bars sizes. Having said that I found that it is too stiff (steps out when straightening up on exit) in the rear coupled with Eibach Sportline and FR track struts. I have backed the rear off to the softest setting, but have not hit the track yet. I am doing that this Sunday.

 

[Burkey]

I use them. The bars are hollow for weight reduction, so apples ain't apples when comparing them to some other bars sizes. Having said that I found that it is too stiff (steps out when straightening up on exit) in the rear coupled with Eibach Sportline and FR track struts. I have backed the rear off to the softest setting, but have not hit the track yet. I am doing that this Sunday.

Thanks for the reply. Would love to hear your verdict post weekend

 

[BlownStang15]

Thanks for the reply. Would love to hear your verdict post weekend

The softest setting worked a treat. I can get the power down perfectly now. What springs / shocks are you running?

 

[Brent Dalton]

I also use the aFe sway bars (and coilovers). They have worked well for me this year.

 

[Burkey]

The softest setting worked a treat. I can get the power down perfectly now. What springs / shocks are you running?

Im running the Vogtland 35mm drop springs on the factory PP dampers.
Quite happy with the ride quality and the way the car sits through a turn (pretty flat) but what I'm trying to do is -
a) remove some of the cars tendency to understeer on turn in (I'm over it)
b) make the car transition into power oversteer more easily and predictably. (Yes, I prefer to steer the car with the throttle)

Did you source the bars in Australia?
Any recommendation on where to chase them?
Cheers

 

[Burkey]

I also use the aFe sway bars (and coilovers). They have worked well for me this year.

Did you find that they made the car more neutral in its handling? Any other significant observations?

 

[BlownStang15]

Did you find that they made the car more neutral in its handling? Any other significant observations?

I have never had much understeer, probably due to how stiff it is overall. Because it was stiff in the back as well I had a lot of oversteer. To fix this I reduced the camber (I had over 2 degrees) and softened the sway bar in the rear.

What will work for you will probably be quite different. Your tyre size and camber is also important to determine what you need.

The key is to buy quality adjustable sway bars so you can tune it.

 

[Burkey]

I have never had much understeer, probably due to how stiff it is overall. Because it was stiff in the back as well I had a lot of oversteer. To fix this I reduced the camber (I had over 2 degrees) and softened the sway bar in the rear.

What will work for you will probably be quite different. Your tyre size and camber is also important to determine what you need.

The key is to buy quality adjustable sway bars so you can tune it.

Thanks for the input. Where did you get the sways from?

 

[Performance nut]

I use them. The bars are hollow for weight reduction, so apples ain't apples when comparing them to some other bars sizes.

I didn't understand this. Are you saying it is less rigid than a solid sway bar of the same thickness or because they are lighter and respond differently?

If it is the first, I always wondered how you would compare the two (solid vs hollow). Equivalent stiffness to a bar 2mm thinner... Weighs the same as a bar 5mm thinner... Be interesting if any one knew.

 

[BmacIL]

I didn't understand this. Are you saying it is less rigid than a solid sway bar of the same thickness or because they are lighter and respond differently?

If it is the first, I always wondered how you would compare the two (solid vs hollow). Equivalent stiffness to a bar 2mm thinner... Weighs the same as a bar 5mm thinner... Be interesting if any one knew.

Torsional stiffness of shafts is proportional to the diameter^4. Outer diameter is more powerful of a driver of stiffness than the wall thickness, in terms of changing one or the other.
http://www.engineeringtoolbox.com/torsion-shafts-d_947.html

θ = L T / (J G)

In this case, L (length), T (applied torque) and G (modulus) would be held constant and you'd be varying the polar moment of inertia.

J (solid) = pi*D^4 / 32
J (hollow) = pi*((D^4)-(d^4)) / 32

 

[Performance nut]

Torsional stiffness of shafts is proportional to the diameter^4. Outer diameter is more powerful of a driver of stiffness than the wall thickness, in terms of changing one or the other.
http://www.engineeringtoolbox.com/torsion-shafts-d_947.html

θ = L T / (J G)

In this case, L (length), T (applied torque) and G (modulus) would be held constant and you'd be varying the polar moment of inertia.

J (solid) = pi*D^4 / 32
J (hollow) = pi*((D^4)-(d^4)) / 32

Think my calculations are all jacked up, I got a significantly lower polar moment of inertia of an Area for the hollow bar than the solid bar... like on the order of 5x.

Since aFe doesn't disclose their thickness, I assumed 2mm thickness (probably too thin but just wanted to play with it). Both bars are 32mm.

J(solid) = 102,943m^4
J(hollow) = 23,422m^4

What I found interesting is the parabolic nature of this. At 14mm of thickness , you are at 90% of the solid bar's J value and more than half the tube diameter is hollow (pretty damn thick tubing but likely some weight loss to still be had). This stayed pretty much consistent with all the diameters I tried.

I seriously doubt the bars are that thick but I have an inquiry to aFe to find out how thick they really are. Some numbers to share (very likely not a bible of all things factual but working with the equations):

A 32mm hollow bar with:

• 2mm wall thickness is equivalent to a 22mm solid bar.
• 3mm wall thickness is equivalent to a 24mm solid bar.
• 4mm wall thickness is equivalent to a 26mm solid bar.
• 6mm wall thickness is equivalent to a 28mm solid bar.

Edit: I would assume you would need to take into consideration material used as well. Having a solid bar with semi-flexible material (relative to metal) versus a more rigid material tube, I would assume that would throw this sort of calculation off.

 

[BlownStang15]

Think my calculations are all jacked up, I got a significantly lower polar moment of inertia of an Area for the hollow bar than the solid bar... like on the order of 5x.

Since aFe doesn't disclose their thickness, I assumed 2mm thickness (probably too thin but just wanted to play with it). Both bars are 32mm.

J(solid) = 102,943m^4
J(hollow) = 23,422m^4

What I found interesting is the parabolic nature of this. At 14mm of thickness , you are at 90% of the solid bar's J value and more than half the tube diameter is hollow (pretty damn thick tubing but likely some weight loss to still be had). This stayed pretty much consistent with all the diameters I tried.

I seriously doubt the bars are that thick but I have an inquiry to aFe to find out how thick they really are. Some numbers to share (very likely not a bible of all things factual but working with the equations):

A 32mm hollow bar with:

• 2mm wall thickness is equivalent to a 22mm solid bar.
• 3mm wall thickness is equivalent to a 24mm solid bar.
• 4mm wall thickness is equivalent to a 26mm solid bar.
• 6mm wall thickness is equivalent to a 28mm solid bar.

Edit: I would assume you would need to take into consideration material used as well. Having a solid bar with semi-flexible material (relative to metal) versus a more rigid material tube, I would assume that would throw this sort of calculation off.

Given the weight of the bar compared to the standard PP rear bar, I would say that the walls would be 5 or 6mm thick.

 

[BlownStang15]

Thanks for the input. Where did you get the sways from?

Stage3 Motorsports.

 

[Burkey]

Think my calculations are all jacked up, I got a significantly lower polar moment of inertia of an Area for the hollow bar than the solid bar... like on the order of 5x.

Since aFe doesn't disclose their thickness, I assumed 2mm thickness (probably too thin but just wanted to play with it). Both bars are 32mm.

J(solid) = 102,943m^4
J(hollow) = 23,422m^4

What I found interesting is the parabolic nature of this. At 14mm of thickness , you are at 90% of the solid bar's J value and more than half the tube diameter is hollow (pretty damn thick tubing but likely some weight loss to still be had). This stayed pretty much consistent with all the diameters I tried.

I seriously doubt the bars are that thick but I have an inquiry to aFe to find out how thick they really are. Some numbers to share (very likely not a bible of all things factual but working with the equations):

A 32mm hollow bar with:

• 2mm wall thickness is equivalent to a 22mm solid bar.
• 3mm wall thickness is equivalent to a 24mm solid bar.
• 4mm wall thickness is equivalent to a 26mm solid bar.
• 6mm wall thickness is equivalent to a 28mm solid bar.

Edit: I would assume you would need to take into consideration material used as well. Having a solid bar with semi-flexible material (relative to metal) versus a more rigid material tube, I would assume that would throw this sort of calculation off.

AFE published some figures on a different thread a while back -

Wall thickness
1.875" front
1.5625" rear

Compared to stock PP Mustang bars-

Front
Soft +22%
Stiff +37%

Rear
Soft 260%
Medium 310%
Stiff 337%

Not sure if any of this helps?

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