Tuesday, July 16, 2013

Independent PFadt Johnny Oconnell Swaybar Review - 2009 Z06, C6 Corvette Suspension Upgrades

Saw this on the Corvetteforum and thought it was such a thorough review on the Pfadt JOC sway bars that I decided to post it (with his permission) 

"I recently created a post regarding trying to improve the handling of my 2009 Z06. I had tracked a C6Z previously and was never impressed with the handling. The ultimate grip was great which is of course was why the car is do darn fast. The problem is that trying to drive it near the limit is so hard. I have never had a lot of confidence in the handling. My previous experiences first led me to the swaybars as the car seemed to be a bit tail happy as I started pushing it. So believing this would help increase my confidence and potentially increase the grip.

http://forums.corvetteforum.com/auto...-bar-only.html

I talked with PFadt and based on my feedback of the car they felt sway bars indeed would be advantageous. The shipped me a set of bars and I was able to get them installed before my first outing and took the following photos. The quality was surprisingly high, not that I did not expect that from PFadt but I have purchased many swaybar sets over the years and the quality exceeded all by a large majority.

The packaging was excellent, you would link this part was easy but it is often overlooked.
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Here is a shot of all the hardware included. The endlinks are fantastic, definitely not McMaster grade hardware, this is the real deal. 
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I know that I am starting to sound like I am getting paid to write this but I am not. The Instructions included with the kit were ridiculously good. They specify all the bolt sizes, tips, tricks and even have many elaborate drawings which indicated exactly how to put everything together.
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Here is the front bar, note that the enlinks are welded on rather than just pinched down. This is not the average build quality.
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This is the rear bar and adjustable endlink
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I also pulled out the scale and weighed both, really no difference.
12.8# OEM Front
17.12# PFADT

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7.70# OEM Front
7.72# PFADT

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Here are a few installed photos, and yes I know the car is dirty but I have not gotten a chance to detail the underbody recently.
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So the bars were very simple to install and the quality was excellent but it does not matter how good they are if they don’t perform. 

My car is a 2009 Z06 which is bone stock with the exception of Nitto NTO5 tires, Carbotech XP10 & XP8 pads and the PFadt bars. The car was aligned with a bit of extra caster & camber, (-)1.1 deg front camber and (-)0.8deg of rear camber, and at the same time the car was corner balanced. The tires wear nearly perfectly to the wear triangles and with the right tire pressures have very even temperature grade.

I am far from a professional driver, as is clear in the video, would like to start racing in an SCCA or NASA sanctioned event but just can’t seem to find the time away from the office. I have been running when I can at my local track and hope to find a trailer soon and hit some other tracks in the Midwest.
I got to run the car at Heartland Parks 2.1 Mile course in Topeka, KS. This configuration is a slightly shortened track which does not utilize the carousel in #2 and #3 and continues down to corners #6 & #7.

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Here is a quick track overview. The short story is that the bars did indeed correct some issues however not as expected. I expected to run the car with full soft in the rear and have neutral handling. In reality full stiff yielded better results in the overall balance. In the higher speed corners the reduced rear sway and slightly over steering characteristics. 

In addition to driving my Z and my S2000 I also got to go around in a CTSV, it was amazing how a huge car like that could respond so well in turn in. My guess is the Magnetic suspension has to be driving the better vehicle response. That being said it is the shocks that I believe really need some help. To further improve I believe a non-progressive spring coupled with better damper would make worlds of difference in the transition periods both turn-in, corner exit and tracking. My next change will be either shocks or better yet a full coilover.

Alpha 0
I am sure the car has it in it but I don’t have the ***** to go all out over this corner. The car is running 130mph +/- and comes over the corner but the steering is a bit lighter than other cars. I thinking a more responsive steering and less rear body roll would make for a more stable corner.

Turn #1
This corner is slightly uphill and feels pretty neutral through this corner.

Turn #5
I personally would like to have a more immediate response from the steering here in the turn in and with the bars in the light setting the car pushed ever so slightly.

Turn #6
This corner often leads to a bit of over steer regardless of the bars.

Turn #7
With the OEM bars the rear really felt like it was yawing very heavily in the rear. With the bar on full stiff the car did feel much more stable. I am still not pushing the car as hard as I can through here but I am working this one up slowly.

Turn #8 
A sweeping turn that can be taken with heavy throttle.

Transition to Turn #9
Now this one is tricky. You come into it at 100-110 and are on the brakes bringing the car down to about 80mph. The problem is the track is not smooth and the car will get light. Trying to get the car stable into the turn is very difficult through here in the Z06. 

Turn #9
Like Turn 7 the rear gets a bit light but there is much less radius so the corner is more consistent.


Turn #10
It was here that the bars felt the most evident. The car would push heavily in midcorner with the bar on full soft. This was very unnerving and is what prompted me to start moving the bars to full stiff.


Corner #11 / 12 / 13 
As with the other high radius low speed corners the car is sluggish to turn in and rotated around the corner better.


Here are a few of the better laps of the day. This was taken with Harry’s Track app on my Iphone so it does not track perfectly but I can’t say enough good things about it.



First Lap
Corner 10 – Notice that I shut down after this corner and babied it back to the start finish. The cars steering went numb mid corner with the rear bar set full soft which rattled me a bit. Moving the bar the mid position the mid corner response went to a more neutral position and surprisingly full stiff was a better feeling. Now I should have listened as PFadt recommended purchase the rear bar and asked them to sell just the front. After some convincing I decided to get both and I am glad I did."






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