How does the 4WD work on the 996?
04-19-2006, 09:38 PM
#2
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Under normal driving conditions it's 5 percent front wheel, 92 percent rear wheel, and 3 percent center wheel... but maybe Porsche's website could articulate it better than I can:
At the center of the Carrera 4’s intelligent all-wheel drive is a viscous clutch that reads traction at all four corners and instantly transfers an additional 5 to 40 percent of the engine’s power to the front axle for maximum grip, even on changing road surfaces. The multiple-disc clutch consists of a series of interleaved plates. The space between these plates is filled with a high-viscosity silicone fluid. If the front and rear axles begin to rotate at different speeds, the frictional properties of the silicone fluid cause torque to be directed towards the plates that are rotating more slowly. At least 5 percent of drive torque is applied to the front wheels at all times. Under daily driving conditions, the average rear/front torque split is approximately 65/35, resulting in laser-true tracking at speed and unprecedented control through the tightest corners.
At the center of the Carrera 4’s intelligent all-wheel drive is a viscous clutch that reads traction at all four corners and instantly transfers an additional 5 to 40 percent of the engine’s power to the front axle for maximum grip, even on changing road surfaces. The multiple-disc clutch consists of a series of interleaved plates. The space between these plates is filled with a high-viscosity silicone fluid. If the front and rear axles begin to rotate at different speeds, the frictional properties of the silicone fluid cause torque to be directed towards the plates that are rotating more slowly. At least 5 percent of drive torque is applied to the front wheels at all times. Under daily driving conditions, the average rear/front torque split is approximately 65/35, resulting in laser-true tracking at speed and unprecedented control through the tightest corners.
04-19-2006, 09:55 PM
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Rob - Good explanation!
Slowpoke - BTW, how did you make out on the rear wheel offset issue you posted few weeks ago? Did the new tires and camber setting solve the problem? Can you post some "before and after" pics?
Slowpoke - BTW, how did you make out on the rear wheel offset issue you posted few weeks ago? Did the new tires and camber setting solve the problem? Can you post some "before and after" pics?
04-19-2006, 10:37 PM
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Originally Posted by riad
Under normal driving conditions it's 5 percent front wheel, 92 percent rear wheel, and 3 percent center wheel... but maybe Porsche's website could articulate it better than I can:
At the center of the Carrera 4’s intelligent all-wheel drive is a viscous clutch that reads traction at all four corners and instantly transfers an additional 5 to 40 percent of the engine’s power to the front axle for maximum grip, even on changing road surfaces. The multiple-disc clutch consists of a series of interleaved plates. The space between these plates is filled with a high-viscosity silicone fluid. If the front and rear axles begin to rotate at different speeds, the frictional properties of the silicone fluid cause torque to be directed towards the plates that are rotating more slowly. At least 5 percent of drive torque is applied to the front wheels at all times. Under daily driving conditions, the average rear/front torque split is approximately 65/35, resulting in laser-true tracking at speed and unprecedented control through the tightest corners.
At the center of the Carrera 4’s intelligent all-wheel drive is a viscous clutch that reads traction at all four corners and instantly transfers an additional 5 to 40 percent of the engine’s power to the front axle for maximum grip, even on changing road surfaces. The multiple-disc clutch consists of a series of interleaved plates. The space between these plates is filled with a high-viscosity silicone fluid. If the front and rear axles begin to rotate at different speeds, the frictional properties of the silicone fluid cause torque to be directed towards the plates that are rotating more slowly. At least 5 percent of drive torque is applied to the front wheels at all times. Under daily driving conditions, the average rear/front torque split is approximately 65/35, resulting in laser-true tracking at speed and unprecedented control through the tightest corners.
One question though, centrewheel?
Thanks again!
04-19-2006, 10:39 PM
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Originally Posted by gota911
Rob - Good explanation!
Slowpoke - BTW, how did you make out on the rear wheel offset issue you posted few weeks ago? Did the new tires and camber setting solve the problem? Can you post some "before and after" pics?
Slowpoke - BTW, how did you make out on the rear wheel offset issue you posted few weeks ago? Did the new tires and camber setting solve the problem? Can you post some "before and after" pics?
May 3rd will be judgement daay on this issue
Porsche dealer are having a super GT3 Cup Racing mechanic do my camber settings, 4 new tires are waiting if the camber doesn't solve the problem, will report then and take pics!
Thanks for the concern, it warms!
04-19-2006, 11:09 PM
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Slowpoke....if you don't have a center wheel, you are screwed. Immediately report to the Porsche service center near you, speak with the service manager, and have them install your center wheel.
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04-19-2006, 11:18 PM
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Originally Posted by Eric - Plug Guy
Slowpoke....if you don't have a center wheel, you are screwed. Immediately report to the Porsche service center near you, speak with the service manager, and have them install your center wheel.
What exactly IS the centerwheel?
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04-19-2006, 11:22 PM
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Originally Posted by Eric - Plug Guy
Slowpoke....if you don't have a center wheel, you are screwed. Immediately report to the Porsche service center near you, speak with the service manager, and have them install your center wheel.
I don't think Europeans totally get "American humor." BTW, Rob - loved the center wheel thing!
04-20-2006, 12:12 AM
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Originally Posted by riad
At the center of the Carrera 4’s intelligent all-wheel drive is a viscous clutch that reads traction at all four corners and instantly transfers an additional 5 to 40 percent of the engine’s power to the front axle for maximum grip, even on changing road surfaces. The multiple-disc clutch consists of a series of interleaved plates. The space between these plates is filled with a high-viscosity silicone fluid. If the front and rear axles begin to rotate at different speeds, the frictional properties of the silicone fluid cause torque to be directed towards the plates that are rotating more slowly. At least 5 percent of drive torque is applied to the front wheels at all times. Under daily driving conditions, the average rear/front torque split is approximately 65/35, resulting in laser-true tracking at speed and unprecedented control through the tightest corners.
04-20-2006, 10:22 AM
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Originally Posted by Zookie
What about the PSM is Off?
04-20-2006, 12:10 PM
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Originally Posted by Slowpoke
If you guys are janking my chain about the centre wheelthingy - American humor really DOES suck!
04-20-2006, 02:35 PM
#15
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PSM has no effect on the VC, viscous clutch/coupling, not directly anyway. The VC has an input "DRIVE" shaft, from the rear, and an output shaft to the front diff'l. Unless there is a disparate, different, rotational rate between these two shafts the viscous fluid remains in its "native", latent state, wherein it only couples about 5% of the drive torque from the rear to the front.
If the rear, primary drive, wheels develop some level of slip or spin (***) the VC fluid will quickly increase the coupling coefficient between the two sets of interleaved plates.
*** This is where PSM might have an indirect effect in that it will moderately apply braking to any slipping wheel or wheels while simultaneously dethrottling the engine thereby preventing any "reactive" VC activity.
If the rear, primary drive, wheels develop some level of slip or spin (***) the VC fluid will quickly increase the coupling coefficient between the two sets of interleaved plates.
*** This is where PSM might have an indirect effect in that it will moderately apply braking to any slipping wheel or wheels while simultaneously dethrottling the engine thereby preventing any "reactive" VC activity.