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4 minute(s) of a 612 minute read
8-5-2013
8-5-2013
Steve, it is very difficult for several reasons.
Our shock is of course not regular, but complicated PASM. Inside of a PASM shock there is a valve that's electronically controlled: to best of my knowledge it opens to reduce damping (Normal), and close to increase damping (Sport mode). For this reason, I would not want anyone to do the revalve job except the people at Bilstein and that, leads to the first problem: Bilstein USA would repair Bilstein shock bought from Bilstein dealer, our car's OEM shock is of course Bilstein, but... it is not a retail product, not bought from Bilstein dealer and, does not carry warranty. I don't believe they will want to touch it, for liability reasons. I actually think they are NOT "allowed" to touch it even if they want to.
Second, as you already know, spring AND damper, together, determine roll/ride stiffness. "Takes two to tango." The problem with gen 1 suspension starts with the soft spring, not the damper per se. In normal mode, you feel the softness of this soft spring. In Sport mode, what Porsche does is jack up the damping sky high to overcome this softness of the spring - a bad way to tune suspension and that is why it is so stiff and jittery.
The appropriate correction is therefore, stiffer spring, not stiffer damper.
Third, assume they will re-valve for you - what rate do you want to re-valve to?? No body knows.
In the end, the alternative is so cheap and so simple, the bonus being you are replacing stock system with something designed by the very same engineer and test driver as the stock shock, that it's really not worth doing anything "adventurous" such as re-valving. The peace of mind of having something that is appropriate for your Porsche, from spring rate, to damper rate, to the design, is why I've mentioned this mod is a no-brainer recommendation if you are looking to transform the handling of our car.
8-6-2013
Yes, in addition, supposedly the ECU monitors multiple data points: acceleration, braking, road surface condition, and adjusts the damping accordingly. Anyway, to best of my knowledge PASM has what appears to be a conventional valve, plus a second valve that's electronically controlled. It's this second valve that when closed in Sport mode causes the system to completely stiffens.
For the record, I am not exactly a fan of PASM; it comes with the car so I put up with it. I believe in the old way: get the right spring rate (the heart and soul of a car's handling), tune the damping for that spring, and no electronic manipulation. For the Bilstein Damptronic, this is achieved by leaving car in Normal mode, with Sport reserved only for track with perfect glass smooth surface.
I think PASM is gimmicky and 99% of the times, even when having fun in the desert, I use the Normal mode. The "best" suspension system is one that is stiff enough to prevent body roll, yet still compliant so the tires still follow road surface (it can't be all stiff), and I do think the Sport mode compromises this compliance by messing with damping. It is much better with Bilstein Damptronic (vs. stock, totally unuseable), but I am still not a fan.
You also have Bilstein Damptronic and GMG sway bar? Assume similar road, with non R comp tire, with pressure differential set to 0, and sway bar set to soft/mid, this system should feel like somewhere between the stock car and a stock GT3. It is stiffer than stock, but not outrageously so. I slow down for speed bumps sure, but most typical road irregularities shouldn't cause wheel to lose contact. This is the compliance that I refer to above, still very good with the Damptronic.