rshanholtz

Does any one have a 987 Cayman or Boxster with Qualfe LSD and Bilstein PSS9's on their car and ..have tracked it? I just acquired this car with this setup and yesterday was my first day on my home track with it. My previous track car is a modified 951. The Cayman S has pronounced unpredictable oversteer at and near the edge. I purposely went out on stock ZR Michelins PS2's to get to know the car. I experienced this unpredictable oversteer in both left hand and right hand turns. It is not quite snap oversteer but as close as you can come to it. I went out with our Club Director who is a former professional race car driver and at 10/10's felt and experienced the same thing. We both described it as a tire patch problem like the car is rotating and losing tire patch as if the camber is off and something is also simultaneosly causing the wheels to shimmy. Has any one experienced this and if so, what corrective action did you take? I spoke with FBL before I took the car onto the track and they suggested that I replace the front control arms with GT3 control arms as they are slightly longer and adjustable adding natural camber and allowing for proper geometry. Additionally it changes the puck from OEM Cayman as the stock puck causes shimmy when threshold braking. FBL also recommended changing just the puck in the rear control arms for the same shimmy problem. Any suggestions or thoughts are much appreciated.

cviles

I don't have an LSD, but I do have PSS9s and tower bracers on my Boxster, and for a while motorsport camber plates up front, and I've never had a problem with unpredictable oversteer. What setting are your PSS9s at now? Have you tried to soften the rear up a little to get some more grip back there?

Also, I've never encountered any strange shimmies, but the car will tramline a bit over grooved pavement. The only "issue" I had was some noise from the solid bearings in the camber plates. My first thought is that you've got a larger problem somewhere -- something installed backwards or suspension alignment & firmness settings really out of whack.

I'd recommend you have a good shop take a long, hard look at the car. My car was very forgiving and predictable, both on street rubber and my PSCs.

rshanholtz

Thanks cviles. I think the Qualfe LSD allows the car to rotate better which only amplifies the problem. If you do not have LSD, the stock Cayman S will not pull around the turn but rather the inside wheel will smoke (see the Stig drive the stock Cayman S on Top Gear). I will have the setup redone, check the setting's on the Pss9's and do the front control arms and replace the rear control arm's pucks. I am also considering the GT3 Sways as they are thicker and lighter. Thoughts?

cviles

Can you provide a little more information about the "unpredictable" oversteer you're experiencing? Maybe a breakdown of what you recall when this happens? Are there no driver inputs that you've been able to correlate at all to the onset of oversteer?

Also, do you know if your car was lowered when the PSS9s were put on? (it probably was) And do you have the stock toe links in the rear? I had some problems until I put a set of adjustable toe links in the rear.

I didn't mess with the GT3 control arms to avoid mucking about with all the shims, and as my car was dual-use a set of camber plates gave me a satisfactory set up.

Also, ask around in the racing/DE forum if you haven't already. A lot of those guys know more about suspension setups than I ever will. You can also ask around at boxcar-racing.com and see what the guys on their forums can tell you.

rshanholtz

The unpridictable oversteer would happen if you tried to force the car to rotate and upset the balance even slightly. Typically you feel the backend start to lose grip and you can use that to rotate like in my 951. In my Cayman the backend would snap out without warning or any early indicators. If I drove the car super smooth and did not push the issue even slightly, the car was fine. But who drives a car on the track that way? After a ton of research, it appears I have three problems. 1. The camber and toe needs adjusted which is where the adjustable front control arms and wish bone will help. 2. The PSS9's may be on the wrong setting. 3. The stock rear sway bars on a car with ABT LSD is not compatible. I will switch the front and rear sway bars to the tarrett sways with drop links. And lastly, a new setup and corner balance will be performed.

RonCT

I think the biggest issue is simply the way the car is set-up. Did you take delivery and then have your shop (Farnbacher sure knows Porsche) set it up to your wants and needs? May be the alignment was off, dampeners set incorrectly, etc.

Before changing anything like sways, I'd have FBL put it on the rack and dial in an appropriate alignment.

Also, if you are serious about the track, you must have GT3 Cup control arms. Otherwise, you're mixing less than 1 degree of negative camber in with a DE-oriented suspension. $1200 for the parts and FBL sure knows how to install and align (they've done past cars for me).
http://www.e-partssales.com/miva/mer...ry_Code=987sus

Feel free to PM or email me to touch base. Are you going to Watkins Glen on 10/19 with CVR?

MoeMonney

The way the Pss9´s are set makes a huge difference in over and understeer. ive seen it on several different cars at the track. I would recommend first checking your setup and dialing it in.

rshanholtz

UPDATE: Everything was done at FBL yesterday. I will have the car on the track next Saturday. I ended up doing everything including: GT3 Cup front adj. control arms and wishbones, tarett sways and drop links front and rear, replaced the rubber in the rear control arms with pucks, adj. the bilstein PSS9's, and a complete aligment and setup. I drove the car to work and it feels better but until you are on the track...