cfjan

Oscar winning, no less!!

Rioja del 73

Could anyone tell me if it is possible to install a LSD in a 2002 996 with PSM?

I drive hard and do tracks as well, always with the PSM off, and would love to have a slip differential if possible.

alexb76

LOL!

That's a great strategy, watch that movie with wife before ordering a new car!

Erik@GBox

Yep there are several options for the 996 street car. The PSM will work just fine with the addition of a LSD. The shop installing the differential may have to make a slight modification to the inside of the differential carrier to clearance the LSD, but this is pretty easy and can be done with a Dremel.

Let me know if you would like some suggestions.

Erik Johnson
GBox Performance Transaxles
(303) 440-8899 work
(303) 895-4828 cell
www.gboxweb.com

alexb76

It looks like there are conflicting views on LSD benefits on 997s.

For what it's worth, I know that on the Cayman/Boxter platform, adding LSD to the car improved their track time quite considerably and a Cayman S with LSD was getting right up to C2S laptimes. Not sure if that's because of mid-engine vs. rear on our cars or what not, but it sure was the consensus that LSD is essential for best handling out of Caymans!

Mike in CA

Absolutely correct. It was option P72 and was packaged with Traction Control with ABD for $1215. I had it on my '99.

GTgears

Yep. I know of a car that picked up 10mph exiting the Busstop at Daytona in testing back in January after they installed our LSD.

I also don't agree with the people saying that you don't need an LSD on a 997, if we're talking about track cars. Pretty much every 997 running the Continental Tire series this year is running either one of our LSDs or a Porsche one. You just don't race ANY car without an LSD. Maybe if you're just doing DE's it's optional, but for racing? There's no debate there.

Rob Heath

This was a great thread and I learned a lot about the LSD option. Really liked the My Cousin Vinny sub-thread.

I have been looking at upgrading my daily driver '88 Targa to a 997.2 coupe. I will also use this car for DE and AX events. Since we do get snow here in CO I have been looking at C4S.

Some of the cars I see listed have the Limited Slip Rear Differential Lock option and other do not. I see how the LSD will help at the track, but will it also help driving in the snow?

Thanks.

GBoxguys

Hey there Todd,

So your question of whether or not a LSD will help with driving in the snow is a good one.

I would have to say yes absolutely there will be a increase in overall car control in the snow with the addition of a Limited slip differential. Especially under breaking.

Give me a call if you have any questions I can help you with, we are here in Boulder as well.

Happy new year.

Erik Johnson
GBox LLC
(303) 440-8899

wwest

BS..Just BS....

Clearly, there is a great deal of confusion between a PSM implemented "virtual" LSD, good, even GREAT for operation on slippery roadbed surfaces, and mechanically implemented Limited Slip Differentials, especially of the torque sensing type.

If your 911 has PSM or even just TC then you have a "virtual" LSD. An "LSD" whereas selective driven wheel braking is used to sustain and thereby redistribute engine torque to whatever driven wheel(s) remain with traction.

PSM's TC, Traction Control, functionality PREVENTS mechanical LSD "operation".

If either rear wheel slip/spins, losses traction, TC applies braking to just that wheel in order to sustain a high enough level of engine torue to still drive the wheel with remaining traction.

Upon detection of even the most minor level of wheelspin/slip TC's "virtual" LSD mode will activate INSTANTLY and brake the wheel having lost traction. If you have a mechanical LSD it will have no "play" in the above case.

Mechanically implemented LSD are of value in preventing wheelspin/slip, acting to pre-emptively redistribute engine torque under certain conditions.

But with wheelspin/slip and PSM active you will INSTANTLY get ABS style braking of one or both driving wheels along, also INSTANTLY, with full engine dethrottling.

Up until most recently a virtual LSD was "reserved", only of real value, for operation on slippery roadbed surfaces and the torque sensing (mechanical) for dynamic, TRACK, driving. But nowadays the braking aspect of stability control, PSM, is also being used to "BIAS" the drive torque left or right depending on the direction of the turn, surplanting, fully surplanting, the need for a mechanical torque sensing LSD.

dasams

Don't all of these cars have adjustable suspension so that camber can be optimized? This will maximize corner speed which will unweight the inside wheel (which may also lift). Hence, LSD will be beneficial. But what about a stock 997? Driven hard on the track, can the inside wheel be unweighted enough in a corner for it to spin under power? Dave