Tbred911

so do all 99's come standard with LSD?

Alon

I had a 1999 with traction control and it had LSD. My 2002 with PSM did not (it was an open diff). My 2004 40 Jahre has an LSD and PSM. Somehow, Porsche got them to work together. I don't know if the PSM settings are different but I can tell you that on the track, the 40 Jahre with the LSD is different and better than the 2002 with open diff and PSM was. I guess the bottom line is that it is possible to run and LSD with PSM somehow.

JimB

I don't think anyone is saying that you can't have LSD, traction control and PSM. Obviously they can be made to work together. The question was can you add an aftermarket LSD to a TC/PSM car. I don't know the answer but I would certainly do a lot of research before spending the $2500 on an LSD. I'm pretty sure that it will be a problem.

Jason,
You've hit it on the head. Many think a Porsche should be a car for "general road use." I do not. Cars are a dime a dozen that can fill that role. IMHO, a Porsche should be a sports car that, with some compromises, is reliable enough to use as a daily driver. To me a sports car is a track car that's been made street legal. Ok, maybe softened a bit but not much. In my mind, you should have to drive a sports car and it should be able to bite you if you screw up. I just don't see a role for driver aids like PSM in a sports car. Again, just my opinion. I'm not trying to start an argument.
Jim

Cupcar#12

I agree with JimB on the track usage of PSM (turn it off if you have it) you want an LSD for the track and any sport driving.
My car has both and frankly i wish it did not have PSM - too intrusive for my tastes - if it only regulated power that would be fine but it uses the brakes as well - on the track i will turn it off but it will activate anyway under braking from what i understand - I am checking to see if i can pull the fuse to prevent it from activating - no testing yet but i will get back to everyone at a later date when i can test it.
personally if you are interested in T/C Racelogic makes a very mice after market system which is adjustable for slipagge. it works by cutting spark/fuel to individual cylinders - non-harmful to the motor and works very well. it does not use the brakes at all and will not help you inder braking only on corner exit in less than optimal conditions.
my 2 cents

Chads996

I am assuming that I have neither. Is this a correct assumption? I supposed I could go to a local parking lot in the rain and do some "skid-pad" testing.

Now again, I see no switches, or information regarding Trac control and PSM. What options were out there for a '99 996 regarding PSM, and trac. control?

Chad

Holger B

My '99 had TC but no LSD. The TC was fine for street driving and didn't kick in that often, but was a nightmare on the track (the car would behave very oddly when I forgot to turn it off).

Chad, if you don't have any switches on your dash, you don't have either TC or PSM. Check your option codes with a dealer or on the web somewhere to make sure.

1999Porsche911

Look at the option codes under the hood and if you see "220" you have the Locking Differential"

UCrazyKid

I'm really surprised that the 996 doesn't come standard with a limited slip. My S2000 had one and it really got the power down when exiting corners at speed. Even the miata comes with a LSD, why not the $80K+ porsche?

JimB

U,
I agree that all Porsches should come with LSD but it really isn't as neccessary in a 996 as in a S2000 or a Miata. The 996 has much more weight in back, much more rubber and a far better chassis and suspension. I've raced a 996 both with and without LSD and the difference is pretty nominal. You're never in danger of lifting a rear inside wheel like you are in your cars which, by the way, are a couple of my favorites.
Jim

Tippy

My car is "peg leg" or "one wheel peel" and I am just fine with that, these cars do not have enough torque to justify LSD, plus the weight over the rear tires helps with traction. If you were S/C'd, I could see needing the LSD.

Ray S

Could the LSD from a 40th anniversary car be fitted to a '02 or later 996?

Ahsai

I always wonder if PSM kind of mimics LSD in terms of improving traction.

For LSD, the spinning wheel will activate some internal clutch plates to slow it down so the power will naturally be diverted to the non-spinning wheel thru the LSD. If PSM applies brakes to the wheel that is spinning, again the power will be routed to the other non-spinning wheel mechanically through the regular differential anyway, no? Isn't the only diff whether the spinning wheel is slowed down by internal clutch of the LSD or by the brake in a regular diff? Is my understanding correct?

- Ahsai

10 GT3

Chad,

Best suggestion is to not worry about it right now. There are only 2 companies that work on these transmissions unlike the German G50 boxes in the GT3s and Turbos. Porsche dealers don't work on them. They have no service parts or tools for disassembly. Even for a leak, the common practice is to replace the entire transmission. You can use a GT3, GT3 RS or Quaiffe diff in these transmissions. The unfortunate part is to have it installed, the transmission has to be removed and sent off since dealers don't work on them. I could have picked up a GT3 diff with low miles for very little. When I added up having the transmission removed and installed, shipping 2 ways and the rebuild for the diff; at over $3K it isn't worth it.

Keep in mind that the factory diff only was 22%/40% lock under acceleration and deceleration, so there is not a lot of benefit in it. The GT3 diff was better at 40%/65%, but they reduced the amount of lockup in the 997 GT3 to 28%/40%. If you are going to go through the expense, I would either go with the Quaiffe or an RS diff.

gota911

You guys do realize that this thread was started 2 YEARS ago, don't you? Chad sold his 996 about a year ago.

LVDell