I have developed and tested prototype suspension modifications on the spindles of a Porsche Cayman S which improves the front and rear roll center static positions, as well as the roll center movements that occurs during cornering. The result significantly improves the handling and the feedback to the driver. Lowered Porsches in particular suffer from poor handling and poor driver feedback due to the suspension geometry changes that occur due to lowering. The poor handling is because of the large horizontal roll center movements during cornering as well as the lower vertical roll center position. I have started this thread in the hope that others who may have created modified suspension geometry to improve the roll center axis position/movement or other improvements can share their experience.

I would like to ask a few questions for those who have had some experience with suspension geometry:

Has anyone studied the Cayman roll axis movement during cornering using computer simulation or other means?

Is anyone aware of modified spindles that are available for the Cayman or other Porsches?

Has anyone tried anything to improve the suspension geometry of a lowered Cayman?

I would also welcome email correspondence directly on this: You can email me at Porsche1VW@aol.com

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Really? I have lowered many many cars and trucks, the ride may suffer but the handling has always improved, or should I say I thought it did. Please explain how low are you talking here, 30-40mm should help handling not hurt it. But I'm no expert so don't listen to me.

Yes, lowering your Cayman by 25 to 30 mm does in fact do bad things to the suspension geometry. The roll center is lowered, and the roll center has large horizontal excursions when cornering. Both of these are bad for handling. This can be corrected with modified spindles, and then the lowered Cayman can be better than the non lowered vehicle. Just lowering most Porsches generally does not improve the handling, and does make for a poorer handling Porsche.

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Two things significantly helped this on my car: GT3 lower control arms and the right alignment settings. Before the right alignment settings I was getting significant understeer at apex, followed by snap oversteer. The right alignment has cured this and the car handles perfectly (even though it is very very low).

I don't know the alignment settings - you would have to speak to the setup master Spencer Cox for that, but you can see in the picture that there is quite a bit of negative rake.

I am interested to see if this can be further improved and if I am masking the issue you describe with stiff spring rates (800/900#). Keep us posted!

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Yes I think what you have done should mask some of the problems. The suspension is so stiff that you have limited suspension travel.

You said that:

"before the right alignment settings I was getting significant understeer at apex, followed by snap oversteer."

In my experience this is typical handling of the stock geometry, with a good competition allignment, and H&R lowering springs. You have been able to improve the allignment with GT3 Control arms and the the high spring rates make for a car that is so stiff that I think you have masked the problem.

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makes sense to me. i am eagerly awaiting news of your improvements!

Have you developed drop spindles for the cayman?

I too am eager to hear more about your set up. The PSS9 was planned as a future mod, so please explain why I should hold off on these.

My work on this is in the early development phase so there will probably not be anything for you in the near future.

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Is there anything for the GT3 or cups that would work for the Cayman? The suspensions parts are very similar up front

Initial understeer then snap oversteer??

Porscha1VW - The characteristics you describe for lowered Caymans are new to me, and may be overstating a "potential" issue. I've got 30 track days on my car now, running advanced/black run group levels and I have what I consider to be a very neutral car. Basically viceless. I've invited several skilled drivers to wring it out on track and they walked away with the same conclusions. My car was setup by Farnbacher with JICs (camber plates included) GT3 front bar, Tarret rear bar, adjustible endlinks and a Quaife. I run 245/275x18" Nitto NT-01s. My car is dropped almost too low for daily driver status here in the Northeast at @ 30mm. Farnbacher has progressivly realigned my car (3x now) more aggressivly, but unfortunately Kip will not reveal the specs. I understand the roll center/geometry concerns you have, but my experience is otherwise.....

Joel's race car is a whole different animal. It is positively slamed, to a ride height that would render it very difficult to drive on the street. At the extreme, geometry concerns are probably valid.....

Yes, that's what i was getting - but i attributed it 100% to setup issues (alignment). Once Spencer fixed the alignment, the car handled perfectly.

Joel-cs, Good question, I need to investigate the GT3 spindle.

Morefun, Yes, I agree there are setups that will mask and/or compensate for the for the poor suspension geometry, but I think they are usually high roll stiffness solutions that miminize the effects of the suspension geometry on the roll centers.

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