No LSD on my car. Need a recommended source >>

Yep, no LSD. Want LSD...eerrrr, Limited Slip that is. I know Quaife makes one ($$). However, any other recommedations? Porsche used part perhaps? And, is this a p.i.t.a. to perform? Chad

If you have Trac or PSM then you have a "virtual" LSD that will probably work better that any mechanical one.

doubtful that is why gt3's have lsd. My 99 also has lsd-

Personal preference...LSD where to buy? Aftermarket or used part? Quaife, Guard? ideas? Chad

I really don't think you can compare traction control or PSM with LSD. They help you make the most of the traction you have. LSD gives you more traction. You are right about the price. A good LSD will set you back about $2500 installed. Jim

Do you need to disable PSM if you install an aftermarket LSD?

Do you need.......??? Absolutely! Trac or PSM will brake the slipping wheel with an absolute minimum of slippage, probably less than 1/4 turn. Even worse, they may interact adversely. Again, tell me why an LSD is better?? If a wheel is slipping, and Trac/PSM moderately brakes only that wheel to prevent it for doing so, the engine can continue to "build" torque. How can LSD do better than that?

WWest, Let me clarify my comments. If you are driving in wet streets or in snow I'm pretty sure that traction control or PSM would be better/safer. If you are trying to go fast, hopefully on the track, would you rather have your bakes keeping one wheel from slipping or would you rather have torque being spread between both rear tires. If your goal is to come out of a corner faster then clearly LSD is better. If you have a very high horsepower car (F1) you would want both LSD to get power to both wheels and traction control to allow you to mash the pedal to the floor without lighting up the tires. We don't have to worry about that too much with our cars. The downside to LSD is that it can induce understeer as you leave a corner. Jim

AS I said, I don't believe PSM and/or Trac would allow LSD to ever "engage".

wwest, I agree that putting an aftermarket LSD in a PSM/Trac car would not work. I don't know how the 40th anv system with PSM and LSD functions. Actually I don't think PSM/Trac have any place in a sports car but that's just my opinion. Jim

I agree with the latter comments. I odly enough have the 99 with both lsd and traction control. In the wet the traction control is actually useful, only because I have bfg's which are super sticky dry but crap in the wet. Otherwise I turn it off when driving hard. PSM works with an open differential just Like c43 amg's. Many people love psm and the like but I can't stand anything that is that invasive. I bought my 99 c2 specifically for the performance lsd c2 coupe lighter. I only wish it didn't have the sunroof for weight, but I like it occasionally-so whatever.

LSD can do better than that by evenly distributing torque so you hopefully avoid a wheel ever slipping. There have been many occasions (especially in the wet) where LSD would have prevented the inside wheel from slipping, therefore preventing my Trac/PSM from cutting the power. Yes, I think some LSD systems shift torque based on slippage, which is why I think they had to tweak the sensitivity of the Trac system on the 40th cars to get the two to work in concert. Given that my car is my daily driver in all 4 seasons, I wouldn't trade my PSM for LSD, but I'd sure love to add LSD to the mix.

Sure, if the car is never intended for general road use. You can get LSD on the 996 Turbo in Europe for example but not sure if that requires a new PSM programme. Reports from those that have it are that it significantly enhances performance on the twisty stuff even with PSM on (ie it reduces the need for PSM to come in).

Obviously the factory can modify the PSM firmware such that it isn't a virtual LSD.

I think my 996 doesn't have either. There are no switches in the cockpit to turn the trac. control off. And...I checked the rear (tires off the ground) no LSD. And...obviously, because of the year no stability control. So, I would like to install a LSD fro track use. Thoughts? C.

so do all 99's come standard with LSD?

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.

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

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

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

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.

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

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?

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

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.

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

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

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.

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

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/graemlins/roflmao.gif

It's all good. Lot's of uselful info from JimB and 02 Carrera regardless.

That is no longer the case, dealers now have the spare parts available to them and can repair the regular 996 style gearbox.

What dealers? Where? I can tell you that I have 3 dealers locally (Boardwalk, Park Place and Autobahn) that will not work on these transmissions. They only do replacements. The German build G96 in the GT3 is a completely different story. I have also talked to Momentum and Advantage in Houston, Suncoast and the Racer's Group and received the same story. Boardwalk puts the entire Porsche parts catalog online and you can't even get the pinion shims. Porsche contracts GKN in Japan to supply new and rebuilt transmissions (service replacement only). Since the contract does not supply parts, they are not in the Porsche parts catalog. GKN was also the builder of the MKIV Supra's 6-speed in Japan and had a similar contract with Toyota and hence why Supra owners have the same problem. The only way to get parts and tools for these transmissions is to go directly GKN in Japan, which Autohaus II does. Since Porsche corporate does not support this practice, the dealers haven't provided this service. Autohaus II is cross-country which mean removing and shipping the transmission to them. Here is some additional information straight from Lufteknic who also does Porsche transmission rebuilds (they are incorrect in that GKN will supply parts in volume):

My local dealer rebuilds them.

I know the original thread starter sold his car and this thread is OLD! For those who are looking here is a great deal. http://mall.rennlist.com/scripts/fea...uery=retrieval

I am sorry, but you have things confused I think. Firstly the G96 series of transmissions are built by Getrag of Germany. G96/00/01 and G96/30/31 are known internally as the Getrag type 450. G96/61 transmission is the Getrag type 448. The Toyota Supra Turbo was fitted with a Getrag 6-speed. GKN is a British company and are only involved with the electronic torque control system in the Cayenne. They may have a factory in Japan, but it has nothing to do with Porsche from what I can see. They do not admit to having any service contracts with Porsche regarding Getrag transmissions. Jason is correct and I have also found lots and lots of companies here in Europe that rebuild the G96 transmissions for all 996s. Here are a couple with one offering a lower cost exchange service as well. http://www.am-tc.be/pdf/Porsche%20Ca...e%20052004.pdf http://www.wrightune.co.uk/g96gearbox.htm You are correct that Porsche dealers did not repair these transmissions inhouse originally because of the "Warranty Contract" between Porsche and Getrag, but this has changed for each transmission system as each model year went out of warranty. I do agree that the high cost of the shop special tooling will put a lot of places off doing this work. The same applies to the engine rebuilding as well. The Porsche 997 transmission is made by Aisin of Japan as is the Cayenne transmission, but this has nothing to do with the 996. The Boxster 5-speed transmission is also made by Getrag. I suppose that Getrag could I would be interested if you could provide the factual link between Getrag of Germany, GKN Group of the UK (long time Porsche parts supplier by the way dating back to the 928 engine conrods) and Japanese manufacture of the assembly regarding the 996 series. Ciao, Adrian. PS: I think the bearings in the transmission come from Japan as they did for the 964 and 993, but this is a Getrag outsource contract and nothing to do with Porsche AG.

One of my local dealers also works on them. He indicated that he does "gear swaps" on them regularly.

A total stab in the dark here, but I'll bet the outsourced transmission bearings came from GKN as bearings are at the heart of what they do.