Fissionx

Does anyone has experience with Quaife limited slip differentials? These are not clutch pack type clutch, but one of the cheapest i've seen, roughly $1,200 or so. I am wondering what reasonable options are there for 996s that do not come with LSD from the factory.
http://www.quaife.co.uk/Porsche-996-...B-differential
-Dan

ElTorrente

I've always been curious about the Quaife, also. I wonder if anyone has installed one of these.

Fissionx

I'm really surprised this thread gets 1 reply while the porsche pronunciation thread is up to 3 pages now; but whatever.

So Guard also makes a torque biasing diff for ~$1,500 for our cars, as well as a clutch LSD starting ~$2,500 and claim to use higher machining tolerances, far better metallurgy, and superior clutch friction surfaces than OEM porsche. You can customize your lock-up ratios and preload in the differential, but can also specify street/track/autox whatever and receive the standard 40/60 lock-up recipe.
The torque biasing differential has progressive lock-up on acceleration, but is open on deceleration unlike the clutch type LSD. Again, the Quaife differentials are torque biasing, but I would personally rather buy from Guard.

I haven't made up my mind yet which I want. I have a factory porsche open diff now, and I am primarily looking for lock on exit. I am running a GT3 suspension and sway bars (rear bar full stiff) and I feel the open diff is simply not designed for this. After the car has taken a set on exit, and i encounter on-power oversteer -> the inside wheel spins, I can't put power down to the outside wheel or rear of the car, resulting in weight transfer to the front, making the problem much worse. I have lost the car in this manner before; not a pleasant experience. I'm not sure a LSD would help before break-away, but I believe it would be more controllable when the rear comes out. I'm SURE their clutch LSD is far superior to the torque biasing diff; but everything is a compromise - money/performance/enjoyment. I would say I am pretty unfamiliar with this subject, so please add to the discussion if you can.

AudiOn19s

I'll bump this just for passive interest. I've got a factory LSD car and fortunatly I can tell my unit is still strong at this point. However I'm sure it'll need a rebuild down the road at some point.

I pretty much expected to do a Guard unit when the time comes....and either a re-gear or at minimum a R&P swap while I'm in there.

Andy

SH || NC

Maybe there are so few responses because I would imagine not too many C2 owners are spinning their inside wheel on the street. I would consider posting in the Race/DE Forums?

UCrazyKid

I looked into this myself. I was used to having a torque sensing limited slip in my previous cars (Honda S2000) and was quite disappointed that an $80K+ car did not come standard with one.

The S2000 had a Trosen LSD in it and it was quite effective at getting the power down. As you have found Quaife and Guard are pretty much the only game in town for Porsche LSD besides factory. Another option is the factory 2004 40th Anniversary edition 911 transmission with it's LSD.

When running a geared LSD you will probably need to run the car with PSM off because the two systems will interfere with each other.

The clutch pack based systems are pretty much universally preferred for performance but as you have found they are more expensive and they do wear out requiring rebuilds to replace the friction pieces.

Depending on how much you want to spend and how much track time the car sees really will determine which direction to go.

I just decided to live with it (open diff).

Andy

Fissionx

Same is true with me. My previous car, m3, has LSD from the factory + 50/50 weight distribution made it easy to catch/control. My car did not come with PSM either...


In consideration with the diffs, I am also battling street vs track compromises. The GT3 stock clutch-pack differential I have experienced made obvious noise and vibration turning sharp at low speeds. Not sure if this is typical or what. Andy, those wevo motor mounts have exposed every rattle in the interior trim / sunroof; starting to drive me crazy.

Paul 996

My factory LSD is pretty much shot or close to it. I'll have it rebuilt sooner or later.

For any track usage (assumed since you really don't need one of these on the street, if you do then I don't want to drive around your neighborhood) the Clutch style is a big advantage over the quaife. If I recall correctly, the OEM LSD has one lockup value for acceleration and another (usually lower) for decel. The decel lockup is very useful on the track during braking. The quaife offers zero decel lockup. Now for the Guard unit, I dunno.

Ahmet

Have you ever driven your 911 in the rain, or over a bump? An LSD makes any car far more predictable when the driven wheels do not have grip -doesn't really apply to viscous LSDs though. I think living without it can be a viable option for some, but I would certainly prefer having it myself.

I've driven or been in I want to say 4 996 MKII GT3s, they all had chatter, some worse than others. It's only noticeable in parking lots. The LSD equipped C2s don't have this issue, which I'm guessing is due to the lock up ratio not being as aggressive. It could also be due to the older design of the transaxle on the GT3s (which have the old transaxle case I believe, but not sure how old the diff design is) At first I found it annoying, but I kind of think it's a cool reminder of how hardcore the car is now. Maybe I'd feel differently if I had to live with it everyday...

AudiOn19s

Check the torque specs again. I had mine too tight at first which made the vibrations worse than they are now that they're properly torqued.

squidracer

Does the LSD benefit our cars other than drag racing and autocross?

Trj

I have an 03 996 x51 set up for the track. I never feel any issues like one wheel spin on exit. My cayman use to have a lot of issues with one wheel spin on exit but I was running stock suspension and street tires. I do not feel like I am loosing anything but maybe I am not pushing it hard enough??? Sometimes its my right front wheel that feels like its not getting traction...

ElTorrente

I'd love to have one for snow/wet days, and any other benefit would be just gravy.

Meister Fahrer

Quaife is pretty respected in the Hot VW aircooled world.

If our 996's could do this?

The Quaife Test: (Mark Herbert RIP)

chris walrod

I would highly recommend staying with a clutch type LSD over that of the Torsen (AKA Gleason-type). The Torsen type does offer rapid locking rates for accel, but fails on the decel, something I feel for the 911 car is very important for decel stability.

Torsen types do offer good yaw control (for RWD cars only) but are rather agressive in which the way they lock.

As mentioned above, if you have PSM, it may fight a torsen just by virtue in the way in which the Torsen locks.