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Discussion Starter #1 (Edited)
Subject car is an '07 CS with a few mods: previous owner installed Billstein PSS 9 coilovers and rear toe links which allows the car to be lowered and have a nice bit of negative camber, at least in the rear. I'm running Nitto NT-01's, typically either white or black group at PCA events, advanced group at others, 8-10 DE days per year. I'm looking for an improvement that will help me maintain more momentum through corners and greater exit speed, so am wondering whether an upgrade to something like Tarrett Engineering front and rear anti-sway bars and drop links would be the next recommended mod? Or would I be better off going a different direction, with adjustable front lower control arms to get some more negative camber up front? Suggestions welcome.
 

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Sway bars are a commonly misunderstood component. Sway bars are a tuning/ suspension adjusting device that limits or reduces traction/ grip at one end of the car or the other. An Ideal suspension would not have anti sway bars (their proper term) nor would it need them. Sway bars limit suspension movement, they tie the movement of the left side to the right side. As you increase a sway bar's stiffness, you DECREASE traction at that end of the car. I.E. If the car pushes too much on turn in, you increase the rear sway bar which is effectively causing the rear to lose traction. You are reducing the rear traction to match the front. Not the ideal way to improve overall traction, right?

Start with replacing rubber bushings with mono balls and adding frame stiffeners to the car. Less pizzaz than new shiny bits and pieces, but a huge and noticeable improvement in handling will be the result. Replace the front engine mount with an aftermarket mount (not a solid mount though) and replace the transmission mounts with the high performance mounts (again, not solid mounts). Do a search here and you will see the various brands of mounts and their pros and cons. Adjustable upper strut mounts with monoballs instead of rubber are another easy to do mod that offer a lot gain in return.

If that wets your appetite for more, the LCA's would be a good third step.
 

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Do the Tarrett competition control arms on all 4 corners. If the Bilstein kit has more than 30k miles on it, replace it with something better from JRZ.
The Tarret LCA's are a good mod, but you should eliminate all the stiction and flex from the suspension first. Instead of repacing the Bilsteins dampers, have them serviced (for under $400 at most good shock shops) from someone that regularly works on Bilsteins.
Chris Harrison @ (623)465-0228 Harrison AutoDynamics is one of the best in the country. Ship the Bilsteins to him when they need service.
 

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Start with replacing rubber bushings with mono balls
This was going to be my suggestion. Esp since you're running an 07 CS with plenty of track days. The OE bushings are probably toast.
I would also suggest a Tarett rear toe arms. They replace the cam bolt with a turnbuckle. The cam bolt is so easy to knock out of alignment.
 

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Discussion Starter #6
Thanks for the suggestions. Regarding transmission and engine mounts, it seems that a lot of folks have gone with tranny mounts but kept stock engine mounts due to excessive NVH, especially using WEVO mounts. Brian C - I see from other posts of yours that you went with RennLine (I think): is this it? HD Engine and Transmission Mount-Rennline, Inc.
 

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Re: front lower control arms, what alignment spec are you running and how is your tire wear or tire temps variation across the tread? If you need more neg camber then the LCAs may be worthwhile.

As far as mid corner speed and getting to throttle early that may be as much driving technique as anything. Do you use a coach? I've gotten good help from a coach and data.
 

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Discussion Starter #8
Re: front lower control arms, what alignment spec are you running and how is your tire wear or tire temps variation across the tread? If you need more neg camber then the LCAs may be worthwhile.
Currently about -1.6 camber front and rear, 0 toe front and 1.5 mm rear (though it's been a year since my last alignment - it's on my to-do list). Front NT01's are wearing much heavier on the outside than are the center or inside. I don't have a pyrometer, so can't speak to tire temps.

As far as mid corner speed and getting to throttle early that may be as much driving technique as anything. Do you use a coach? I've gotten good help from a coach and data.
Valid point - having an instructor ride along always leads to incremental improvements, and I know I should do it more often.
 

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Currently about -1.6 camber front and rear, 0 toe front and 1.5 mm rear (though it's been a year since my last alignment - it's on my to-do list). Front NT01's are wearing much heavier on the outside than are the center or inside. I don't have a pyrometer, so can't speak to tire temps.



Valid point - having an instructor ride along always leads to incremental improvements, and I know I should do it more often.
More neg camber in front should help tire wear. I have GT3 LCAs and shims for about neg 2.2 deg. My last set of NT01s were fairly even wear. Corded on the inside mainly from the drive to/from track.
 

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As Zedcat indicated, when you go beyond -2 degrees, you begin to cord the inside of the tire within 5 thousand miles or so of street driving. If that's not an issue, then you may want to go that far or a little more in camber. I'd recommend aftermarket control arms that allow fully incremental adjustment rather than the GT3 style that require discrete shims. Elephant Racing also makes robust suspension components that are price competitive. As you get beyond -1 in the rear, you may also need new toe links to allow enough toe adjustment since adding camber pushes the toe significantly.
 

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Keep it simple, no monoballs or engine or transmission mounts. Do front LCA, change the springs in the PSS9 to the Spec Boxster setup (400# F 500# R) available from Tarett. Add adjustable sway bars,all work. Do a track alignment. Read my article on Suspension over on the Cayman Register.
 

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Chip,

I have a lot of the hardware mentioned here--PSS9s, RSS LCAs, Tarrett sway bars, rear frame brace, adjustable rear toe link, and NT01s. My car is nicely set up. I run 3 deg negative in the front, and close to that in the rear, the shocks on full stiff front and rear, and the sways one setting in from full stiff on each end. There is a lot of caster in the front, too--so much so that the tires nearly touch the fender liners when the wheel is turned all the way to the lock. I shoot for 30-32 psi hot, and get pretty even readings cross the tread. My car also had an OG Giken LSD, which has a lot to do with stability under braking and the ability to roll on the power early.

My next step will be to JRZ or Ohlins dampers.
 

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Chip,


My next step will be to JRZ or Ohlins dampers.
I find that having a high quality damper does a ton for body control, that you would otherwise need to address with thick swaybars. I love that the 981 has clean adjustment points up top, to reach the damping knob. I picked JRZ one way over Ohlins for simplicity and reliability - trying not to rebuild all of the time like a four way.
 

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Thanks, Bill. They are on my list. I think 2-way adjustables are about as complicated as I want to get.

A couple weeks ago I had a ride with a friend in his worked-over 981S. He bought the car already built, and he's not much of a technical guy, so he didn't know that much about it (amazing driver, though).. The car felt incredibly planted. He told me it had JRZs, but he wasn't sure which ones. I took a look--they were 12-31 3-way adjustable remote reservoir race shocks, which retail at a cool $13K! I guess you get what you pay for.
 

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ChipB, I do have Tarett adjustable sway bars and Ohlin coilovers. I started out adjusting the shocks to reduce understeer as it was pretty easy, especially in front, just turn steering wheel to steering lock and turn the shock adjuster knob clockwise or counter clockwise from behind the open wheel. I found that as some readers have pointed out, sway bars have a greater influence in balance, so I am now backing off the sway bar on the end that is losing grip rather than increasing the sway bar on the opposite end.

I use my car as a daily driver so I change back to canyon driving settings on both shocks and sway bars, before I leave the autocross track.
 

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Lots of good suggestions so far. Depending on how much you want to spend I would do this:

!. GT3 A-arms for more negative camber, corner balance and alignment. (my setup) I prefer stock 987 motor mounts and trans mounts . YMMV
2. Go big and get the JRZs, A-arms, CB and align. $10k all-in but they are that good. My brother has them on his 987 and the car is a track scalpel compared to mine.
 

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Lots of good suggestions so far. Depending on how much you want to spend I would do this:

!. GT3 A-arms for more negative camber, corner balance and alignment. (my setup) I prefer stock 987 motor mounts and trans mounts . YMMV
2. Go big and get the JRZs, A-arms, CB and align. $10k all-in but they are that good. My brother has them on his 987 and the car is a track scalpel compared to mine.
+1. You can put a suspension as good as GT4 or better. I think of my car as the GT4 2.7L.


Sent from my iPad using Tapatalk
 

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Keep it simple, no monoballs or engine or transmission mounts.
Monoballs and engine mounts are the simplest mods that can be done.
Do front LCA, change the springs in the PSS9 to the Spec Boxster setup (400# F 500# R) available from Tarett. Add adjustable sway bars,all work. Do a track alignment.
Adjustable LCA's and stiffer springs AND an adjustable sway bar are the most complicated of all mods.
Each one has an effect on the others. Track alignments are some of the most discussed topics. There is no one right alignment for any car. Every setting of an alignment has it's plusses and minuses, it is a constant game of compromise. Do you want better slow corner turn in? Do you want better high speed straight stability? Those two are mutually exclusive of each other. You want more of one then you give up more of the other. Oh, wait, you also want high speed corner exit control?? Add a third component to that equation and now you have a TOTALLY different alignment and set-up.
Read my article on Suspension over on the Cayman Register.
Did, not impressed.
The reason that the springs didn't work as planned on your car (which you are telling him to copy) and you had to change dampers is because the PSS9's are tuned to the spring rate of the supplied springs. You changed the springs but didn't revalve the dampers to work properly with the new spring rate. That is why you had to (in your mind) buy different dampers. If you go to a higher rate of spring, then the PSS9 damper must be revalved to properly dampen the spring. You could have revalved the PSS9 dampers and saved thousands vs buy the magical beans (triple valve, remote canister.....) The problem with your advice and some of the other advice is that you tell people half the story.

Never change springs without the appropriate modifications to the dampers. They work as a team, a set tuned to each other.
 
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