Originally Posted by Basic

Part of our day was spent practicing left foot braking to control the slip angle, if the PSM turn back on under braking I never experienced it as once your slip angle was beyond the point of no return around you would go. Full braking made absolutely no difference to the stability with PSM turned off.

All I am posting is my real world experience, I've read on here all sorts of things about PSM that I've not experienced. We spend the entire day literally trail braking every turn as you had to do that to initiate the slides. PSM on it was not possible to do anything as its very agressive especially on the ice.

Here's an interesting writeup

http://www.deter.com/porsche/PSM.html

From the owners manual

When PSM is off, the vehicle is stabilized as soon as one of the two front wheels enters the ABS control range.– When PSM is off and Sport mode is on, the vehicle is stabilized as soon as both front wheels enter the ABS control range

Lots of differing information, my real world experience doesnt match up. PSM is an excellent system to keep the driver safe. On the icy track you just could do nothing to loose control with it on. With it turned off I have never experienced it re-activating, psm is very obvious when it comes on.

Originally Posted by pwdrhound

If you have PSM off with the dash button, PSM will be off under acceleration but it will turn itself back on under braking. This is why you could bounce off the rev limiter with the tires spinning to your hearts content. To oversimplify it, PSM off with the button = PSM off under acceleration, PSM on under braking. This is why PSM off still sux at the track because you can't effectively trail brake....

Originally Posted by pwdrhound

When running back to back 20 min sessions (with 30 min cool down between sessions) at the track, the rear brakes would run almost 100 degrees cooler when running with PSM fully deactivated versus PSM just turned OFF via the dash switch. I'm sorry, but if you think PSM is fully off when selected off via the dash switch, well, you're wrong...

Originally Posted by Basic

So where does this extra heat come from? Above you say it's off on acceleration and on during braking. So one would expect the brakes to be the same temperature or are you saying the PSM comes on while your braking to brake more? How is it effecting your trail braking?

You state that since your testing shows 100 degrees more at the rear brakes I must be wrong, could you not feel the PSM doing something on the track while it was off to create this extra heat? Seems like it should be noticeable don't you think?

The DDC stabilizing the car in an over/under steering situation is quite noticeable with the PSM on.

Originally Posted by pwdrhound

Yes, that is what I'm saying. If you have PSM off with the dash button and you drive the car hard enough into the turns and trail brake to initiate rotation, PSM will turn itself back on and begin to pulse one of the rear brakes to bring the car back in line, essentially adding more "braking force" to whatever rear wheel needed to bring the car back on line. If you do this repeatedly PSM will begin to cook your rear brakes. Essentially PSM is constantly dragging one of the rear brakes as soon as the yaw sensors detect an excessive slip angle with the car under braking. Been there, done that. Ask any accomplished driver that heavily tracks their 996tt and they will tell you the same thing. It is much much easier to rotate the car under braking with PSM totally out of the loop, not just switched off. I religiously take temperature reading of each brake rotor and tire at the end of each run and keep a pretty good track of this. The rear brakes absolutely positively will run cooler with PSM totally defeated vs just switched off with the dash button. Trust me on this. I am not making this up.