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4 minute(s) of a 612 minute read
9-22-2011
Unfortunately, I have only one answer for you: Stop driving it on bad roads. Or go back to stock suspension. This is a classic case of ride vs. handling: If you want nice smooth ride, the handling is going to be lousy; if you want sharp and precise handling, the ride is going to suck. No car has ever escaped from this trade-off of ride vs. handling; not Ferrari, not Lexus, not Bugatti, and your Porsche won't either.
That said, I have one key question to ask you please: what are your tire pressures? Did you set your TPMS to partial load, and run the differential reading at -1 or -2? (TPMS tends to over-read pressure by 1 to 2.5 psi.)
Second, give it a few days and let your derriere adjust - you do get used, to a small degree, to the stiffness. Third, you are not using the Sport setting of PASM, are you?
BTW, I have not found ride height to affect stiffness. This is a key design parameter of both springs and dampers: spring rate and damping factors should not change when used within specs. In other words, used within designed specs, there is nothing to suggest stiffness should change with height, if it is set up correctly.
9-23-2011
What is the best tire pressure for the Turbo on street tires? This topic has been discussed several times on this board, so here are some info and my humble opinions for those new to this car:
1. The "correct" tire pressures for the Turbo are NOT those numbers on the door panel. These numbers (37/44) are not just high, they are way too high and represent the **maximum allowed** tire pressure for a fully loaded car. The correct pressure recommendation is in the manual page 289: 33 front , 39 rear, at 20 degrees ambient temp.
2. The best way to adjust the Turbo tire pressure? For regular street driving, use the on-board computer - instruction on page 114 of the manual. Set the tire to Summer, set the load to Partial Load (this is the key). Then check the differential reading: maintain this at 0 throughout. The car's OEM tire pressure monitor tends to over-read by 1 to 2 psi (for example, when it reads 30, the real pressure is 32) so I actually run mine at minus1 or so, but that's another story. For most people new to this car, 0 throughout is a good start. In Southern California weather, my car typically starts out around 30/36 in the morning, then becomes 33/39 after a few minutes of driving.
3. If you find yourself over-inflating the tires to make it feel right: it's quite possible you are unconsciously stiffening the tires to compensate for the very very soft spring rates of the stock Turbo. The stock car has too much body roll and lazy steering response and one way to improve and stabilize this defect is stiffening the tires - that's why it feels "better" with over-inflated tires. This of course is not the right way to do things; for one, tire traction is not good when tires are over-inflated. If you think you fit in this category, the proper correction is in that Bilstein thread in my signature LOL.
4. I use a digital pressure gauge like this one http://www.amazon.com/Deluxe-Longacre-Digital-Pressure-Gauge/dp/B004BOH7CU (there are cheaper versions) as a reference to make sure the car's system is correct. As mentioned, I've found that the car over-reads by 1 to 2 psi, and I believe others on this board in general have observed the same.
5. Remember tire is part of the suspension system, and tire pressure could be adjusted, **within reasons**, to influence both comfort understeer/oversteer behavior. Soft front tires promote oversteeer, stiff front tires promote understeer. I wrote "within reasons" because tire pressure of course also affects traction, so I don't think it's a good idea to over-use this feature. FWIW I run my differential reading about -1 in the front, and 0 in the rear, for all the reasons I mentioned in 1 to 4 above.
6. Whether that tire pressure is correct depends on the ambient temperature of where you are. For every increase of roughly 10 degrees F/5 degrees C, the tire pressure goes up 1 psi. The TPMS's differential reading in the car takes car of this, and this is why I recommend using that reading for street driving.
