Guy’s, the sprung vs. unsprung weight issue was driving me bonkers last night so I did some research. I found a white paper titled “Hollow vs. Solid Sway Bars” that was prepared by a company that produces a couple of the suspension components that I use on my track car.
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Here is the link: http://www.whiteline.com.au/docs/bul...%20Swaybar.pdf
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Page 5 addresses the mass issue and as we suspected only a portion of sway bar mass is considered unsprung.

 

Here are some pictures...

 

Very nice discussion. So around 6kg (solid) versus 3kg (hollow) per sway bar, but only about 10% is unsprung weight?
BTW, my wild guess was on the money!

 

I just replaced some "dirty hoes" If i go 100 cell cats it might even sound better... or keep the cats and no mufflers...

 

Can,
So far what is your take on all this?

1- Go hollow or not?
2- Which bar gets your pick?
3- If you do not want to pic a bar, how about a set up?

 

Are you trying to get me in trouble with all the pro's lurking on this thread? I could not touch their experience/knowledge and am learning from them as well.

I should ask again, do you have Tarett or RSS drop links in your car? In my experience, metallic heim joint drop links will significantly increase the effect of the sway. (Imagine trying to push a heavy object with a rubber stick that bends, then replace the rubber stick with a metallic one.)

Anyway, all else being equal I would vote for hollow. Of the bars we've talked about so far: RSS, GMG, TPC are hollow; H&R and Agency are solid.

RSS: Highly reputable/trustworthy vendor. Used by many on this forum, and by your tuner, with great success. Size of RSS bars are very similar to GMG's.

GMG: Same. A real Porsche racing team and had a Turbo which they used to test the bar. Bar made by Eibach, which supplies Porsche OEM springs; this is a plus. OTOH, although they tested the bar with lowering spring, I don't know if any trial was done with real coilover system like Bilstein or Moton. This is what I have on my car currently.

TPC: Another Porsche racing team. I enjoy reading their description of how they are testing the bar, with stock and Bilstein, JRZ, etc., and are making adjustments. This is important to me, not just sway bar but any after-market component: Actual testing on actual car, by people with knowledge. In fact if I don't already have GMG, I would be tempted to give this a try.

That said, so far it seems the bars' specs come very close to each other. So maybe they are all the same? Kidding. I would think what's equally important is the adjustment of each bar (using the different holes) so it fits in with the rest of your suspension system.

What is on your car now?

 

I apologize for the delay. They were finally able to do the tests as we discussed. This test involves calculating the stiffness for the overall bar based upon each bend that the bar has in it. Here are the numbers showing the Agency Power sway bars stiffness over stock at each level of adjustment.

 

Thank you for the information. How did you come to these numbers?

 

Our sway bar manufacturer (US Based) has to build a test jig. They then calculate the difference at each bend of the bar. This then has some equation that to be honest I dont know. It is compared to the stock bar which they have there from my car. They are the engineers so they know how to calculate. As he told me on the phone, this is something you cannot simply take diameter as I thought.

I hope you are enjoying your sway bars still.

 

Thank you for taking the time to test and post the important data. This is what makes 6speedonline unique and this thread really has become one of the most interesting ones on sway bar, data wise, that I've read!

That Agency Power front sway bar's numbers are strange in:
1. how low the front OEM number is, and
2. how high the percentage increase is. 110 to 170% !?

I am puzzled (and would be concerned) that the proportional increase is so much higher in the front than the rear. If true, this would upset the balance of the car quite a bit. Front sway bar that much stiffer would worsen understeer -- something you don't want with the 4WD Turbo.
Did the Agency Power engineers have anything to comment on this?

 

From what I have been gathering on all this, it would be almost an ideal situation to get the front set up on the rear...

 

Any update on this question?

 

Dan, can you test and post the GMG bars as well? H&R? RSS maybe.


I don't care what anyone says, I want the stiffest one.


I can volunteer to send my H&R bar in for testing if we can get a comprehensive list of who's the pappy when it comes to stiffness.

 

I just read this entire thread, thanks for the info guys. Any updates on this?

 

Unfortunately no update AFAIK, if it's the Agency Power anti-sway bar you are asking about.

My thought remains the same: In general, to reduce the inherent understeer in the AWD 997 Turbo, you would like to soften up the front bar and stiffen the rear bar, relatively. The Agency Power sway bar does the opposite of this.

Regarding the title of this thread, I would like to add that IMHO, the stiffest sway bar is not necessarily the best, *if* that's what you are using to stiffen the suspension system.
IOW, if you want stiffer, use stiffer spring, not stiffer bar.