KrazyK

Porsche would not approve of your blasphemy. I would think that as the rears lose more grip the PSM would have to notice the fronts are not pulling. Can you test this and post for those wondering? I bet if you tried it on jackstands it would play havoc with PSM.

Imo000

Is it PSM or just Traction Control?

Hardback

I have RWD on my car now as well. The only time PSM has ever engaged for me is on the track when the car is being hustled through corners. I turn mine off as soon as my helmet goes on. PSM is useless on the track as it does spooky things when the car is loosing grip, like checking the brakes in a 100 mph off camber sweeper. I should install a limited slip diff to take full advantage of this mod. But an LSD from Guard Transmission is around $2500 plus install... ouch

Dennis C

I believe all the AWD 996 cars are equipped with PSM. Also, PSM works by applying the brakes to various wheels to "right" the car when it's sliding off if the intended line of travel. I believe it will also cut engine power if necessary. If you ever do a track day in a 996 and forget to deactivate PSM, you'll burn through your rear brakes pretty quickly.

5CHN3LL

I agree with Hardback - PSM has caused me far too many skipped heartbeats - having one of the front brakes lock when you're driving near the limit isn't fun at all.

The combination of AWD and PSM has always made the car a little neurotic. AWD with PSM disabled still resulted in the car fighting with itself - the rear end WANTS to swing out, and you want to countersteer to catch it, but it never really happens right. It's like trying to get a date's bra off for the first time - not nearly as smooth as you'd like it to be.

Driving it today felt much more natural - the one time I was able to kick the rear end out, it was very mellow and predictable - much more like my Boxster used to be, much more like my Corvette is. I know the 911 rear end can get away from you when you start adding more speed, but I'll pay $1 to anyone who does the conversion and then decides it was better the old way.

5CHN3LL

PASM may cut power; I do not believe PSM does anything except modulate the ABS channels.

Capt. Obvious

The AWD system is 100% mechanical, there are no electronics or sensors of any kind associated with it. All PSM cares about is whether the wheels are turning or not, not if there is power going to a specific wheel.

5CHN3LL

The steering feel alone is worth doing the mod. The steering is now as light as my Boxster's was.

Dennis C

PASM only has to do with suspension, so it doesn't cut power.

I thought there may be traction control associated with PSM that would cut power.

5CHN3LL

Heh. I have no PASM, so it's just some other acronym to me. I have not noticed PSM reducing engine power. If it's doing it, it's much more subtle than the ASR in my Corvette... which is why "press the ASR button" always follows "turn the key."

5CHN3LL

Some really good reading from Renntech (link below):

"Included in PSM is the ASR anti slip regulator, and ABD. If one tire slips the automatic brake differential applies the brake to the slipping tire, hence reacting and behaving just like a limited slip differential. If BOTH tires spin, then the ASR slip regulator kicks in and retards the ignition and cuts power so that traction is regained.

Turning PSM OFF will disable the ASR, four corner braking montiors, and pitch/yaw sensors...... BUT the Automatic braking differential stays on at ALL times up to 62 mph... That is why you will notice that even with the PSM OFF light showing you will still see a separate flashing warning light letting you know that ABD is still kicking in during certain rear traction sliding situations to try and behave like a limited slip differential...."

http://www.renntech.org/forums/topic...-insider-guys/

KrazyK

Mine will indeed reduce power in a forced oversteer. I have tried it with PSM on vs. PSM off. This is not possible w/o sensors.

Capt. Obvious

That has nothing to do with the AWD being there or not, though. It has to do with the speed differential between the four tires (wheel speed sensors), along with input from the yaw sensors.

5CHN3LL

The only sensor involved with the front wheels is the ABS sensor (which is why you have to reinstall the stubs from the half-shafts, since the ABS encoder teeth are part of those castings).

The output to the front differential is via viscous coupling - so there is no computer magic involved with the F/R torque split. I didn't bother looking, but the plate on the front of the transmission is still spinning away, even though there's nothing connected to it.

It's awesome that people who haven't done the mod are the ones arguing about how it can't possibly work.

fpena944

I can attest to this...

One weekend at the track I didn't deactivate PSM and my rears wore out faster than my fronts!