Limited Slip Differentials

Besides 1999, which 996 model years had limited slip differentials? In doing some research, it seems after 2000 (or 2001?), LSD was removed from the options list once PSM became standard on the 996? Does the current 997 series 911 have LSD--the Cayman and Boxster Ses do NOT? Short of cost--I can't understand why Porsche does not include a mechanical limited slip differential with their venerable 911 models--my humble E36 M3/4-door comes standard with a limited slip diff (as do all M cars)??!! I want LSD because I do PCA DEs (currently a CIR PCA and MOR PCA DE instructor). Thanks in advance.

I'm no expert here but my thoughts are that ABD Active Brake Differential took its place and is no longer needed. I believe the ABD uses the ABS braking system to sense wheel slippage and brake that wheel which essentially does the same thing as LSD without using mechanical clutches in the diff.

Active braking systems DO NOT do the same thing as LSD, but do just the opposite. It slows the wheel(s) down to keep them in sync. With active braking systems, the spinning wheel is braked while with LSD, the non moving wheel is engaged. LSD equals better performance when drive traction is at risk.

2004 40th anniversary model has a LSD. I believe they are the only non-gt 996s available with a LSD

It was an option on the 1999.

I have TC, LSD and ABD on my 99 Only downside is that I don;t do much to take advantage of it

LSD is a wear item and requires maintenace about once a year on a track car or every 2-3 on a street car.

The 40th Annie will be tough to find at a reasonable market price. Thanks for the tip. Interesting the 40th Annie uses PSM and a mechanical limited slip? Brakes are also wear items, and the rear brakes will get worn much faster with ABD engaged often. It's a copout for Porsche--for whom "there is no substitute"--to brake individual L and R rear wheels--a la ABD--to serve as a substitute for a mechanical limited slip diff. Sounds like I'll be shopping for a '99--the "driver's 996"?

While I do have a "driver's 996" myself, I'm not sure I'd agree with your assessment. Put me (or you) in my car and then in a 997 and I'm quite sure the lap times would be better in the 997. It's a better car with or without a lsd.

Turn off the 997's PSAM and other electronic "sissy" controls and the same car with LSD is much more controlable around the track and will produce better times. For people who cannot handle competitive speeds around the track, it wouldn't matter.

I've driven a student's '99 996 to its limit potential--it was downright scary and fun at the same time. My BMW E36 M3/4-door's perfect 50/50 fr/rr weight distribution is forgiving at the limit while my student's 996 was not nearly so. It's an eery feeling to feel the back end rotating so much in his '99 996--my student tried to duplicate my speeds in his car, but we ended up in the weeds--no harm no foul. Electronic aids kill power delivery, and brake individual wheels for the car to regain traction (which again is slower if the driver is trying to adjust the car's cornering attitude with the gas pedal).

So what exactly are you saying Sleeper?

Electronic aids help inexperienced drivers, but hinder experienced drivers. With my student's '99 996, PSM would have kept him out of the weeds, but I would not have had as much fun rotating the back end of his car at full speed LOL I noticed the 2000 996es had LSD as optional but also have traction control as standard? The 2000 sounds like a winner?!

Ah....much more understanding when it is sweet and simple

Cool avatar--what track?

Las Vegas Motor Speedway Outside Course. Fun, but no elevation change but LOTS of dirt runoffs in the desert

To my knowledge, the 2000's did not have the LSD option. The 1999 had it with TC which could and should be turned off perminently. Secondly, teaching people to drive with all the "sissy" controls (IMO and experience) is not the best approach. So much of succesfull driving involves the FEAR factor and giving a student a crutch while learning quite often instills too much confindance and allows them to achive maximum handling out of the car with a parachute. However, this has done little to teach them how to control a car properly. The "sissy" controls also kick in too soon compared to the actual ability of the car to safely navgate certain corners. We use to teach people to drive in a car with no camber and artificially light in one end. This allowed the student to actually learn how to control a car that experiences unpredictable things. After experience in driving a car like that, they could get into a properly setup car and have a little more respect for what it could and couldn't do and how to safely adjust when the car hit it's limit. However, for those that simply want to get around the track quickly without even knowing how to drive, then the "sissy" controls come in handy.

I completely agree with your assessment on electronic driver aids. Same goes for sticky R-compound tires and inexperienced sports drivers--Hoosiers cover up bad technique. In looking through Edmunds.com, they list LSD as an available option for the 1999 and 2000 911s--but the LSD option disappears from the options list from 2001 to 2005. The list of options are shown when you go through the "customized appraisal" worksheet. If what you say is correct about model year 2000 996es not having LSD as an option, then I'm limited to the 1999 996. While the market asking prices for the '99 911s are within financial reach of most enthusiasts, I'd say we're a bit intimidated by first-year production run glitches as is the case with most car models--even Porsche 911s--I suppose?! I've read in Excellence magazine that early 996es (and 986es) were plagued by oil leaks--most were caused by a faulty main seal--while others were caused by porous crank cases (the oil actually leaches out through the metal). Most should have been replaced under warranty by now??

The 40th Anniversary cars made in '04 have limited slip.

The 40th annie cars are WAY OUT OF MY REACH. Thanks though! Now this 1999 996 is more of what I'm looking for. http://cgi.ebay.com/ebaymotors/1999-...QQcmdZViewItem St Louis MO isn't too far to drive to check this car out. They posted an options sticker showing number 220--isn't that the option code for limited slip differential? Also how do I know if this car has a bonafide throttle cable, or electronic throttle?

All the 1999 C2's had the cable. The 1999 C4 was egas.

Sleep, that looks like a very fair price for a low mileage 99 with good options. Provided it checks out. Just bought one too so I have bunch of the codes handy. This car has 3 spoke steering wheel, LSD, TC and ABD, Xenons, Hi Fi sound, Painted crests, Oval Chrome exhaust tips, Heated seats, etc. Similarly, I just sold my Black/Black 1997 M3/4dr. Will miss that car all around. Best of luck! -paul

Thanks for the clarification! Paul, thanks for the option code definitions. I was hoping to keep the M3/4-door--I love that car--it's great for instructor DE'ing--lots of stowage capacity--and I can take 3 students for demo laps LOL. I'm not quite ready to pull the trigger this soon--frankly I thought it would take longer than a night to find the right car--but you're right this car looks cherry--I especially like the LSD/TC/ABD, Arctic Silver paint, clear turn signals, and 18-inch wheels. I'm afraid of oil leaks with a Porsche--my bimmer's tight--it holds all its fluids .

I hear ya, but all high-end cars need TLC. The M3 was mostly bulletproof but there were little gremlins like the plastic water pump impellers, plastic radiator, rear shock mounts. etc. 996's have RMS and if it happens is $800K. Get a warranty for around $2k or just be prepared to shell out some cash if something substantial goes. My M3 surprised me one day with a blown AC that cost just over $2K to fix, not under warranty anymore. There are some guys on here with cars over 100K and counting. Cars that surely at driven hard and often. If you snoop around here will find the guy(s) with blown motors, bad trannies, etc. But there was the same type of stuff on the e36 and e46 boards. I am happy with the move to the 996. Much more of a pure Sports car over the very practical and very good M3. A little more than 2cents that time

Dont let the RMS scare or deter you into a warranty. I just did my RMS for around $300... $230 of that was the special tool...It just takes a little bit of time and patience. Look at it as paying yourself $120/hr to do the work! -Keith

I had a '99 with the LSD/TC (they dropped that option in 2000 when they brought out PSM) that I bought new in April '98 (sold it 2 years ago to get the GT3). Don't believe everything you read, it was a great car. I did lots of problem free DE's and the RMS was replaced under warranty and never leaked a drop again. With this many years on them now, it should be easy to sort out the good from the not-so-good. If one was going to have an issue with the dreaded RMS, coolant expansion tank, tranny, etc., it would have done so by now. Don't pass up one that checks out mechanically, meets your needs and is reasonably priced.

IMO, this should not deter you at all, the current market price for the 99 996's make them a steal,..a lot of car for that money. It is a bummer that you have to look for the earlier models for the LSD,..but at the end I'm sure you'll love the car on the track. Good luck with your purchase.

Sleeper, Those guys (Schmitt) are about 10 miles from me. If it comes down to it, I could cruise by and check the car out a bit. I might be able to find the PO as well.

Ahh, so it's true the 1999 996 is the year with optional LSD until the 2004's 40th annie car. Can't trust Edmund's data then. They misled me to think 2000 was the last year for LSD option (eventhough they list PSM as optional that year for the 996 911). Yes, with the E36 M3 I did the rear shock mounts (they were bad at 65K miles). I had a thermostat go out and replaced the t-stat housing from the plastic to the metal housing (68K miles) . Surprisingly my water pump had the metal impellers--and it was fine (mine is an April 1997 build). Other than brakes, new RE050As and a slightly leaking PS hose (replaced), the bimmer's been a bulletproof weekend road warrior and PCA DE instructor car. What's great about the bimmer is that I can do a lot myself (except for messy or big jobs like gearbox/diff fluid changess, clutch jobs etc.). I'm hesitant about how much I can do myself with a 996. That would be great. Indy's about 6 hours away, but if you don't mind doing a little "recon", I'd appreciate it much, sir. I'm especially concerned about oil leaks. The Ebay rap sheet on this 996 says the PO was meticulous--and that's good news. This 996 is the best one I've found on the net. My wife's been nonchalant about this hunt--she's seen me go through my PorscheQuest before (the last PorscheQuest was for the right 3.2-L Carrera, but I got a BMW 97 M3/4 instead LOL). BTW, I have to compliment you all. This has been a great board. I've been a registered user for 24 hours, and not once have I seen a negative post. Thanks for all the help and encouragement in researching these stunning cars.

Sleeper, Just curious did you carfax it yet? It is not the definitive source of info but steered me away from a few.

Paul, no CarFax check yet--but that will be a definite, "must do". Russ, do you have a recommendation for an independent Porsche shop that can do a PPI there in St Louis? No worries if you don't have a shop in mind. Just being proactive, and optimistic, that I'll actually get that far with this car LOL.

Reid Vann - 968-4100. Pretty sick I know that number of the top of my head. LOL. John Rhodes is the service manager. That's the independant shop to go to in town. Parktown Porsche/Audi would be my suggestion if you wanted a dealer to do it.

Thanks, Russ. I'll keep this thread bookmarked now! BTW, here's another '99 996 with LSD option. The owner took the time to snap a pic of the option sticker too. This one's in Atlanta. More options, more money, more miles--I like the sports seats--red interior is a bit "loud". The St. Louis car is nicer inside and out, but this Atlanta car has an intake and exhaust. Does one need an ECU tweek to make the most out of these mods? Does an intake and exhaust bump up hp to at least 300? http://www.autotrader.com/fyc/vdp.js...e=&cardist=413

Alright - Here comes an Idiot question: I have a 99, how do you know whether you have a LSD or not? I know it has TC but is there an easy way to tell the LSD?

See hood sticker above. From what I've read in the last 36 hours of being a Rennlister, Traction Control is a group of systems consisting of a mechanical locking differential, electronic anti-slip regulator (cutting power to drive wheels), and electronic active brake differentiation (individual L and R rear brakes applied up to 62.5 mph). Option codes are 220 (locking diff), 222 (anti-slip regulation), and 224 (active brake differentiation). Apparently the traction control option code is P72 which encompasses all these option codes. The cost was $1215 at the time of purchase. Note that the Traction Control option was only offered in 1999 for the 996. From 2000 on, Porsche switched to PSM (except for the 2004 40th annie car which has PSM and a locking diff). Good luck!

cohare, open the front hood and look on the inside of the hood. You will see an option code sticker like the one posted above your post. Look for code 220. If you are lucky you will see the code and know that you have a LSD.

my '99 has TC but i don't belive it to have LSD. car is 100 miles away so i can't check under the hood just yet

Let us know when you check the hood sticker!

No need to hold back. Tell us what you REALLY think!

i remember reading something about a manual way to check if you have a the LSD by rotating the wheels off the ground...but i forget what you're supposed to check for

Actually the VERY FIRST Porsche I found turned out to be the right one. I was never able to match that combo of price and options again. Like you, I thought "wow, this is easier than I thought!" and I waited and ended up settling. But I should have jumped on that first one. I've regretted it ever since!

You should definately post that DIY!

Thanks for your help guys, looks like I have all three options, 220, 222, 224. I guess if I cared that much I should have checked it before I bought the car.

If the wheels are off the ground and when you sping them, they both spin the same way, then you have LSD

Woo hoo! 220, 222, 224 the option code trinity of traction control on the '99 996. On a more serious note, I joined RennTech.org to research engine problems on the 996es. Based on the little I've read, the 3.4-L motors had mechanical problems with engine failures and subsequent replacements (most under warranty--with some out of warranty--Porsche paid 1/2 the cost to replace the motor). Many of the failures seem to be caused by the pesky rear main engine seal, while others were replaced due to faulty castings. I've read on RennTech that the 3.6-L motors were more mechanically sound...bummer since the 2002 3.6-L motor 996es came with PSM (no locking diff option). http://www.renntech.org/forums/index.php?&CODE=00

I dont think you will ever come across a 996 3.4l that has an engine failure still to come... Any 3.4l that was going to go, would have allready gone. As for the RMS, it won't cause an engine failure. The only way that could happen is if it was left leaking for such a long time that you ran out of oil in the motor. That or somehow the seal managed to fall out, which you would immediately realize the loss of oil and shut the car down... With that being said, it is fair to ASSUME that a RMS won't ruin an engine. Get the RMS fixed, get it fixed right, and enjoy the car...If it leaks it leaks...It wont hurt anything, pre-mature clutch wear at the most, and it's minimal.

I just hate oil leaks. My old twin turbo '93 Mazda Rx7 (Type FD) used to leak oil--that drove me nuts. My current BMW doesn't leak anything--and it holds 7 US Qts of motor oil in the crank case! Thanks for the reassurance though. The board members here have been generous with their experience and knowledge of these '99 996 P-cars. -Manny Lozano

Manny, I know what you mean. My 944turbo track car used to leak like a freaking sieve. It's so awesome to move my 996 from the garage and to see a spotless floor where it was sitting.

I hate oil leaks too, that is why i replaced mine...The key is to replace it when you need to do the clutch. If it is dripping, then yes change it. But if it seeps a little, wait till you have a reason to change it... However, if you buy or rent my special tool, you can change it 4 times a year for $25 in parts and 5 hours of your time! My suggestion on hoping for the best and letting it go applies to people who will pay the dealer quoted $1,300... -Keith PS i used to have a 700+hp turbo e36 m3. I miss it, but the Pcar is WAY more solid...And we hold around 9qts

So, how about that DIY?

- As has been mentioned the RMS failure is unlikely to cause engine damage, unless it was totally ignored. - I don't think the 3.6L motor was improved over the 3.4L motor for oil leaks, rather the RMS seal itself has gone through improvements. So, the current , I think the 4th generation seal is suppose to be better. - It does not leak oil unless the RMS is leaking and it can be repaired (it's not like you'll have a car leaking oil all the time,...if the RMS fails, which is a rare occurence, then it may, and then it can be replaced, and it may never leak again.........Now, this is DIFFERENT from a car that leaks oil all the time, so it's may not be like your RX7

Love to see that DIY...

I know i know!! I will have it up this weekend. I got a crazy week this week... It won't be so much of a DIY, step by step guide, but pictures and my impressions on the whole ordeal... -Keith