Limited Slip Differential--a MUST HAVE for '99 996 C2?

Following up on my old thread https://rennlist.com/forums/showthre...9&page=1&pp=15 I've been looking at '99 996es for awhile now, and VERY FEW '99 996es on the market come with LSD (limited slip differential). Factory '99 996 LSD units are 20% lockup acceleration and 80% lockup deceleration, and GT3 LSD units are 40/60 (or 45/65?). Some say it's tough to differentiate between the 20/80 and 40/60, so for serious track work a 50/80-combo is the way (LSD from Guard Transmissions). Questions: 1. For '99 996 owners who do NOT have LSD, and have never owned a car with LSD, how has life been with the car? 2, For '99 996 owners who do NOT have LSD, BUT had a true LSD (not the torque-sensing, or torque-biasing type, but clutch-pack type) in a previous sports car, how has life been with the non-LSD 996? 3. Is the Porsche factory LSD for '99 996 worth spending time looking for an LSD-optioned '99 996, or should I find a nice '99 996 without LSD and count on installing a 50/80 Guard LSD unit as my first mod (pricing seems to range between $2500 and $3500 installed). I have 10 years of track experience with 5 of those years instructing with PCA and BMW CCA, so for me the LSD is an option I could use--but I want to read opinions from ACTUAL owners of these cars (with or without LSD)--in hopes that I might not miss the LSD afterall?? This a great forum for researching and buying Porsches. Keep up the great work. -Manny Lozano ("Sharked" 1997 BMW M3/4-door+Dinan)

There were character limitations on the Poll Title, so here is the complete title:

[QUOTE=SleepRM3]Following up on my old thread https://rennlist.com/forums/showthre...9&page=1&pp=15 I've been looking at '99 996es for awhile now, and VERY FEW '99 996es on the market come with LSD (limited slip differential). I didn�t even realize that I had LSD on my car until I read your thread and decided to lookup the option codes on the sticker under my hood. That was a pleasant surprise! I did my first DE without knowing I had LSD. I know that my driving skills need to improve before I can drive the car close to its limits. I plan on improving my skills during the Lone Star Region�s DE in May. Lee

[QUOTE=rleeq] Great find! Does your car have the traction control package or the stand-alone LSD option 220. The TC package includes ABD (automatic brake differential) and ASR (anti-slip regulation) with the LSD diff. If you have traction control, you need to disable it every time you start on track, otherwise the TC will kick on, and not allow the LSD to function. Enjoy your car and be SAFE!

SleepR....i have option 220 which is the LSD as well as the traction control (no PSM just basic traction) and I love the car (with TC off that is)...i can't imagine owning a car with no LSD (I have some basis to compare but no to another porsche ATM)

[QUOTE=SleepRM3] Yes my car does have TC. Thanks for the tip on disabling it for track days. It seems that TC is good for only stopping wheel spin on takeoff, not that I have a problem with controlling that. Does TC have any positive attributes?

PM JimB about the necessity of and LSD on the 996. If memory serves he has extensive experience with and without. Additionally, he's one of the quickest 996 drivers out there.

Not having LSD would not prevent me from buying a nice 996 given all other things right... I mean it is nice to have an all but unless you're on the track I dont think its something REQUIRED. You can always add it later as you said and by waiting for a factory LSD you are passing on probably many nice cars.

[QUOTE=rleeq] Yes. For normal street driving in slippery conditions, TC is a good safety net--if your skills are still developing as a performance driver. For track TC slows the car a bit and prevents the drive torque from being well-applied at corner exit. Enjoy your 996 SAFELY!

I love my 911, but it bothers me that even a Mustang comes standard with a LSD and my car doesnt...

I looked long and hard to make sure my '99 had LSD when I bought it becuase I do track my cars. However there is a school of thought that is of the impression that the factory unit is probably fairly well worn by now anyhow and nearing a need for a rebuild so if you find the right car without LSD it's not a huge deal to add later is you wish (though it could be $$$). Andy

I have one with LSD and happy that it does because I am a car nut. But I would say that for autox having one makes a difference since the course is tight. But for track DE events and those that run R compounds I would ask how many of you are breaking the rear end loose around corners at the track (when the car is driven properly that is) ?? Obviously having one is better than not but given the high grip rear end on our cars I suspect that those that don't have one don't notice wheel slip coming out of corners (we only have 300 hp). Now in the rain.. another story.

Paul--I intend to track the 996 in the rain (see my avatar).

SleepRM3, I was in the same boat as you and passed on 996s w/o LSD. I finally found one and am very happy. I have the LSD w/traction control. When I AX or DE, I turn off TC. For normal driving it's on.

I hear you, and the poll results are also agreeing with you, but this car is SO NICE http://www.cars.com/go/search/detail.jsp?paId=224011358 I called about it. No runs, drips, and no LSD Louisville's only 100 miles away, and I can have Bluegrass Motorsports Porsche do the PPI. I've been reading posts from 996 track drivers about how the 20% locking factory LSD in the '99s aren't stout enough for serious track work; I'd end up wearing out the 20% locking LSD at the track--necessitating an upgrade to a 40/80 or 50/80 Guard LSD? The 996 racers seem to like the higher %slips in an 80/80 combo LSD, but for me that's too much--as mine will see mostly public roads with only 4 to 5 DEs scheduled per season--thus a 40/80 or 50/80 LSD.

i'm no mechanic, engineer, or expert of any kind, but isn't LSD less important for a 911 since most of the weight is over the rear, thereby giving a bit more traction (versus a front-engined, rear-wheel-drive car, where more traction is needed)? just an uninformed thought....

Apparently this reasoning is why Porsche engineers don't think LSD is required on the 911 either. They figure 99.95% of their new-911 buyers (median age of 70) aren't real "racers"--they just like to drive a racing legend (the 911). Unfortunately, I'm part of the 0.05% that would actually drive his 911 as intended--although I'm no racing legend as a driver LOL

First, I think this is way over rated. An LSD isn't going to drop multiple seconds off you lap times or make you a better driver. The amount of power transfer with the factory diff is very low. For really top drivers, they can gain control (mostly powering out of corners) with a more race oriented diff. The RSR diff seems to be the best for the track. Not a lot run guard diffs or swap to LSDs on these cars, mostly because there are very few who will open one of these transmissions up. It would be a very different story if you were talking about a GT3 or a 993 with a G50 based transmission. With all that said and done, if I were to look at a 99' I would look for one with the LSD and no traction control. This is very theoretical, becasue just for the production improvements, I would prefer to look at a 2000+. Keep in mind that Porsche best driver Walter Rohrl ran the exact same best time (8:17) with a 99' ROW M030/LSD Carrera Coupe as he did in an 02' ROW Std/non-LSD Targa on the Nurburgring. Although the Targa had 20 additional HP and the later improved chassis revisions, it also had about 250 extra lbs.

A good article on Porsche limited slip differentials. http://guardtransmission.com/velocity.htm

One of the quickest? (just kidding) I've tracked 996s with no LSD, with an OEM LSD and with a Guard. Most drivers would be very hard pressed to tell the difference. The combination of great suspension, lots of weight and lots of rubber really negates the need for an LSD. Do I have one in my race car? Of course but I'd never worry about one in a street-track car. There really aren't that many corners where, when driven properly, you generate meaningful wheel spin. T7 at Sebring and T7 at Putnam come to mind but even then a little spinning can help get the car headed in the right direction. Some cars like the Mustang have LSDs to compensate for crappy suspension not because Ford is building a better sportscar than Porsche. Just look at Grand Am cup. The 997s you see racing are very close to stock. The Mustangs and GTOs are full factory race cars. BTW, I've been told the factory LSD is pretty weak and won't last long on the track so if you find one it probably isn't working anyway. Jim

Jim, based on your experience as an expert 996 racer, would a Quaife torque-biasing (1-way) LSD be good enough for my needs? My 996 would see very little track time (3 to 4 DEs per season?). My local Porsche expert (Terry Heath of EuroMotorworks http://www.euromotorworks.com/ ) can install a Quaife LSD in my prospective 996 purchase for $3216--parts and labor (the GT LSD would be $4036; and the GT3 LSD would be $4339--parts and labor). Thanks!

Sleep, An expert 996 driver I am not but thanks anyway. I really can't speak to the difference between the different LSDs. I think you'd really have to drive them back to back on a tight track to decide. You don't want too much lockup or you'll be heading for the weeds so I'd guess the Quaife might be a very good alternative. I would say that if I has $3K to spend on making a 996 a better car this is not where I would spend it. Jim

SleepRM3, I can understand where you are coming from having previously owned an e36 M3. But in all honesty I think you are making a bigger deal about this than you need to. My recommendations is to buy the nicest 911 you can afford. Note that some options are easier to add later than others... 3 spoke steering wheel, different wheels, even an aero kit if you wanted. I had a list in my mind that would make the car special to me and set about looking for that combo but was willing to make some trade offs based on what I knew to be reasonable. Now as far as the LSD goes, I think you have done a ton of research already and know that there are viable ways to add one should you determine that you need it. Key point here.. Buy the car, do a few DE's and then decide. Some advice for you. Buy a car with either a US M030 or ROW MO30 suspension otherwise coming from the M3 you won't be too happy with the base 996s handling. The rest will be outstanding... much better brakes, much more top end than you are accustomed to and with the M030 suspensions (note that there are even better options available but M030 is a great starting point) much better handling as well (provided you run the big rubber on 18s like these cars like and not the puny 17s with 7s and 9s). After driving one for a bit and learning the thing around the track you may come to the decision that the LSD is not needed after all. I wouldn't run out and add it right away without having a baseline. But if in the end you are hell bent on getting an LSD go for it .... it is your cash

Great advice, fellas. I appreciate it very much. -Manny

Hey ! I look forward to seeing that avatar change to a Pcar. All it does if remind me of my Black E36 M3 that I still miss... but the Pcar helps makes up for it.

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

Manny, One thing that came to mind since we pm'ed. Since you have an M3 currently you will relate to this. Let's say it is raining outside, you hop in your M3 and turn off the ASC/TC. Now put it in 1st and take off nice and easy and then stomp on it.... hmmm not going anywhere..shift 2nd quick.... hmm same as 1st. How fast are you moving...? not much huh. Pretty much just standing still Try the same thing in the rain in a 996 C2 with tires with reasonable thread and see how little if any wheel spin you get. Surprised the crap out of me the 1st time I did it.

Yes, in the pouring down rain, I was hounded by a fellow instructor driving stock a 996 C4 aero around Mid Ohio--damn, that thing stuck in the wet. Good to know the C2 has good wet stick too! I'm looking forward to owning one of these fine machines (the '99 996). M

Sleep RM3, I was in almost the exact same boat about 2 months ago, and ended up buying an '02 C2. For background, I tracked my e46 330ci for 7 years, and instructed for 2. The decision basically came down to this - do I want to wait for a 99 car with factory LSD option, or do I want the relatively more reliable '02+ cars? I am sure through your research you had read about the potential issues with the 99 - 01 cars. Do I want a LSD? Am I absolutely amazed when I found out that LSD is not even an option for 99+ car (40th anniversiary not withstanding)? Yes and Yes! However, I figure that I will already be getting a huge upgrade from what I had, and it will take time for me to learn and connect with it. My learning curve starts again and I will throughly enjoy the process. I am also the type of person who values stability and predictibility. Therefore, in the end, I decided to look for an '02+ car, and gave up looking for the right 99 with factory LSD. There is also the thesis that the factory LSD may break down easily. That kinda make sense. Afterall, this will be a LSD on a ~8 year old car, and the originaly driver may be a relatively aggressive driver (loosely defined here) if the LSD option was chosen. I'd hate to have to spend the money to replace a broken factory LSD, when I could have gotten an 02+ car and do the same thing on a later date of my choosing. Just my 0.02. I hope that was helpful.

Helpful post. Thanks. Actually I'm not clear on some of the MkI 996 reliabiilty issues, except for the smaller (3.4-L) motor, oil seepages from rear main seal or crankcase metal housing, and engine failures--which appears to be possible with any 996 regardless of mileage. Do tell...!

I believe the RMS issue is more prevalent in pre '02 cars - this can be remedied by looking for a car that had the RMS replaced. However, from my research it appears that some 1999 engines may have a casting flaw that makes them weaker and more prone to go kaboom. Maybe others can chime in on this, but I think that kinda makes sense given that it's a first year production car, and in general I tend to avoid first year anything on a car.

Yes...that about sums up what I've read. Some of this may be factual, others urban legend. There seem to be many MkI 996 owners that are quite happy with their cars though (shrug) ?

As a driver that does 30-36 days of DEs and racing each year, I have to say that the LSD is just not going to matter if you only do 3 to 4 DEs per season. In my book, that means that your car will primarily be a street car. I would focus on getting the nicest 996 you can afford, and an LSD would be a bonus. I would not forego an otherwise nice car OR drop the money on an aftermarket LSD. For the few weekends you will use the car on the track, I bet you would never notice the difference. Plus, keep in mind that stock or near stock 996s tend to understeer anyway (sure you can tune it out, but still . . . ), so LSD could actually make the issue a little worse under certain circumstances. Why not look for a 40th Anniversary, which has LSD?

Galun.... do a search. seems that 02+ cars have RMS early replacements, as do 997s and even the GT3s. BTW early means under 60K miles. So the 1999 996 is the 1st year? In the USA/NA.. where did all the 1998 996s go that were sold in the ROW? Must of blown up. Here we go again. The 3.4L engine goes kaboom. RMS causes it. yadda yadda. LOL So, what is a RMS... it is a little rubber seal that costs under $20. You just have to take the transmission off to get to it as is with most things on our cars. Everything is hard to reach.. Even a spark plug change is a PITA in a 996 (no room).

Excellent points (you echo JimB and Paul). As for the 40th An that's some dough! I'll be saving a few years for that car (I'm a poor Bimmer owner LOL )

OK, so just view an LSD as icing on the cake. If you find a car that you otherwise like and it happens to have an LSD . . . brilliant! If you find a car that you like but it doesn't have an LSD, no biggie . . . .seriously.

Yes...sounds reasonable. BTW, I like your sig animation (it morphs through all the generations of 911s as you stare at it).

Sure 02+ cars have the RMS replaced. I am not saying they are immune - I am saying it seems to be less prevalent. How about the casting flaw issue? Is that just an urban legend?

Sorry if I am testy. It's been a long week and it's Friday. Pesky developers with their bugs, pesky sales people with their deal prospects, pesky field techs with their rtfm questions, pesky customers with their feature requests, pesky analysts with their roadmap reviews. There much better.

Wait, does this mean an LSD could increase understeer in a 996? How do you tune out the inherent understeer in the Carrera (besides foregoing an LSD)?

I believe a LSD increases understeer becuase it increases traction of the rear wheels. It can be dialed out with adjustable sway bars by softening up the front and increasing the grip there. The GT3 sway bars have 5 settings in the front and 4 in the back I think - there is plenty of relative front and back settings for you to play around with.

This is a good thread that recently popped up on the gt3 board. It gives a good explanation of how LSDs work. https://rennlist.com/forums/showthre...ferrerid=43587

If you are going to put in a new LSD... guard would be the way to go regardless of the ramps. They can build what you want, the quality is much better than the Porsche part, and it cost less. My dealer price to replace mine was $3,600 for the part, guard $2,400. For a GT3 90% track a Guard 50/80 is the way to go. Call guard and ask them the question. There is nobody that knows more than them.

[QUOTE=Galun;4031024]Sleep RM3, I was in almost the exact same boat about 2 months ago, and ended up buying an '02 C2. For background, I tracked my e46 330ci for 7 years, and instructed for 2. The decision basically came down to this - do I want to wait for a 99 car with factory LSD option, or do I want the relatively more reliable '02+ cars? I am sure through your research you had read about the potential issues with the 99 - 01 cars. Do I want a LSD? Am I absolutely amazed when I found out that LSD is not even an option for 99+ car (40th anniversiary not withstanding)? Yes and Yes! However, I figure that I will already be getting a huge upgrade from what I had, and it will take time for me to learn and connect with it. My learning curve starts again and I will throughly enjoy the process. I am also the type of person who values stability and predictibility. Therefore, in the end, I decided to look for an '02+ car, and gave up looking for the right 99 with factory LSD. There is also the thesis that the factory LSD may break down easily. That kinda make sense. Afterall, this will be a LSD on a ~8 year old car, and the originaly driver may be a relatively aggressive driver (loosely defined here) if the LSD option was chosen. I'd hate to have to spend the money to replace a broken factory LSD, when I could have gotten an 02+ car and do the same thing on a later date of my choosing. Just my 0.02. I hope that was helpful.not true I have a factory lsd on my 99 c2]

Wow. I was still young when the message you replied to was posted

I have a 99 996 Cab with factory lsd - That is the reason I chose it over other 996 cabs I was looking at. It is a pretty rare option for some reason.

Oldie but goodie. Love to see these old threads come back to life from time to time. Yes, imho, every 996 should have an LSD if you want to truly maximize 996 handling. Not just the 99.