How can one find the torque distribution between front and rear axles? Is it fixed or variable? Specifically asking for Cayenne S.

 

Your Cayenne has Porsche Traction Management (PTM) all-wheel drive, with an electronically and map-controlled multi-plate clutch. The PTM adjusts the bias as needed according to conditions. The first generation was rear biased, with a 62/38 split. The 958 had a slightly more balanced 52/48 split [EDIT: Another source says 60/40 split for the Diesel and S Hybrid]. I can’t find figures for the current generation but it is rear biased “as much as possible”, especially in Sport and Sport Plus Mode. The PTM is capable of transferring up to 100% power to either axle.

You can monitor your drive distribution in real time on the instrument panel. Use the right scroll button to select the drive distribution screen, pictured, below:

 

I ran a little test to see how power affects drive distribution. Conducted on dry pavement. Wet / Snow would presumably produce different results.

• During low power, cruise, and engine braking, drive torque was steady at ≈ 75/25.
• High power showed a torque shift to the front axle; about a 50/50 split. This remained steady from about half throttle up to full throttle.
• Reverse gear showed a pronounced torque shift to front axle during acceleration. Best guess was 25/75 (That was tricky, so no photo of that test!)😳
• No differences observed between Normal and Sport drive modes.

 

Porsche Traction Management PTM uses a non-clutched torque distribution in most (e.g. 25/75) cases, and actuates a multiplate wet clutch for a different (e.g. 50/50) torque distribution. The non-actuated torque distribution uses a different gear ratio between front and rear axles (final drive ratios) to create differentiation (speed difference) in the multiplate clutch.

In the 958 Cayenne S example below the final drive ratio difference is 3.09 (rear) vs 2.73 (front). The 2.73 vs 3.09 ratio difference creates differentiation in the front-rear torque biasing clutch. When a solenoid is energized by the software, clutch plates are compressed thereby changing the torque distribution. I haven't seen where the 9Y0 PTM is changed vs 958 in its principle of operation.

https://newsroom.porsche.com/en/inno...ics-15050.html

https://press.pla.porsche.com/downlo...hmentid=242155