911SLOW

The cup LSD pack costs here 300 to 400 EUR depending on the source, plus labor typically 150 to 300.

P.J.S.

Just a heads up but you do not have to but the entire guard unit - you can buy just guard internals and put them in your existing housing

GTgears

You can find a more detailed discussion of this in the LSD Buster thread but there's some very specific reasons that we don't sell a "clutch kit" in the same way that Porsche does.

Reason number one is that the internal dimensions of these factory LSDs have a very wide range of what the cups (aka ramps) measure. We see them anywhere from a low of around 70.5mm to a high of just shy of 73mm. That's a range of 2.5mm. But every single one of these street diffs we take apart have 2x 1.15mm bell. washers, 4x2.0mm plain steel plates, and 4x2.7mm brass friction discs. Also, every body we measure has an internal dimension almost always at 94.6mm.

So, you can do the math, but part of the reason you see so many different experiences with respect to performance and durability when these things are stock is because of the huge range of tolerances. Some of you guys are rolling your car off the showroom floor with a .5mm internal gap in your LSD and others of you have a gap that's in excess of 3mm. This is also why we demand that if you are not replacing your ramps that your LSD be apart and measured before we pick exactly what thickness and spec parts we're going to send you. This is also why you get hit with 20 questions about application and driving style and primary track beforehand. We're looking to hit a particular gap and behaviour of your LSD that suits you specifically.

Then there's the 8 plate Cup Car kit that is being discussed. Versus the 21.1mm thickness of the stock plates, discs, and bells, the Cup Car kit is 22.2mm. So just off the bat you're 1mm tighter than you used to be. But they still treat it like a one size fits all situation. If you've got one of those diffs with 71mm ramps, you're the lucky guy who is going to have a reasonable gap in there. But if you're that guy who has the super tight 73mm ramps your mechanic is going to be trying to stuff more than 95mm worth of material into a 94.6mm space. For most people you won't have any problem, and Porsche seems to be getting more consistent on their ramps recently with the 2010 diffs I am seeing through here. But at the same time, that doesn't really seem to matter because they've got those near useless 28/40 ramps on them and most people that want to track the car are pitching the ramps and getting something performance oriented.

And that's where the big price difference between our rebuilding service and just throwing in Cup Car plates comes in. The price of our rebuild clutch kit is pretty similar to Porsche's rebuild clutch kit, with the biggest difference being the one I already mentioned is that we send you a stack of plates that are measured specifically to you and your LSD. It's changing the ramps where it starts to add up. A set of ramps costs almost as much as the clutch kit, so if you decided to change your ramps, then it's quite a bit more. But we are in the 996 GT3 forum, and as we've discussed in the past, you guys have pretty dang good ramps and locking factors and didn't get screwed the way the 997 guys did, so it's not an expense you really need to be thinking about in my mind. For 996 GT3 owners, just getting a decent set of clutches in there is what's going to make your LSD work properly

I'll add just one closing remark, and that is that the vast majority of teams and privateers racing Cup Cars are manipulating and adjusting the preload and stack height of their LSDs. Some are changing the ramp angles as well, when class rules allow. I'll give you one guess where they are buying the individual components to make these adjustments. We make 6 different thicknesses of belleville washers. PMNA makes 1. If a team wants to increase or lower their preload, they aren't getting their parts from Porsche.

Regards,

Matt Monson
Guard Transmission LLC

apochiraju

thanks a lot for the info Guys. I will give a call to Guards and figure out what its going to cost me .. cos im badly in need of a LSD rebuild.

ninerguru

Matt, very informative posting... Thanks!

roberga

If the LSD is OEM than: The answer is always yes.

jim911

What about a quaife diff?

mkk62

my guard lsd rebuild was 900 plus mailing cost sending it to them and back...had it pulled and sent in while doing lwfw, clutch etc...quick turnaround and good experience with guard

mike

Q&A

I dare to say my OEM LSD is still working reasonably ok after 45K street miles and 10K track miles (those are mine). When i park my car in reverse, and in need of a full lock turn, my LSD still stutters, bounces and makes noise like a 1940 ***** Jeep. Another good way to test it is by entering the highway for example in a mild, fast turn, and accelerate, and de-accelerate while in this turn while accelerating. A non (working) LSD car would push you more into the turn, where a working LSD would push you OUTside the turn. This is my routine LSD check and i can confirm that my OEM LSD is still pushing me outside into the highway armco if i was cruising with one hand entering the freeway.

In my opinion the lifting one wheel test is not thorough enough because of the progressive character of the differential. it is designed, even when new, to be able to turn as light as possible without driving forward. I thought the LSD only starts to work slightly after 10 mph or so.

My rear toe angles are completely OFF after 4 or 5 track days and i think this is unfortunately (personally) the only 'flaw' in the car. With more then 20 track days this year, x $100 for the full alignment you can do the math.

So my advice would be, check your alignment and check the way it really should be done. (most common shops have NO idea how to set up a GT3 that is used for track days) And with a rebuild LSD you also want to start using it, while all the other 'possibilities' are excluded so you can really notice the difference.

Tires are also not something to be underestimated. Just a badly worn, or too much heated up (or too cold) set, can mess up your entire handling too.

Some track turns / braking zones also cause more instability than others just because of the tarmac quality or bumps. Check it on multiple braking zones at different tracks before final judgment.

And the final, only way, to really test (measure) it, is with a torque wrench (taking the drive shafts off)
Prior to taking it out for repair, you should do this anyway to be even more sure. I also did that 5000 miles ago and it was still within Porsche's tolerances proving that not all LSD's are being shot after 16K miles ;-)

.

jim911

Any more opinions on this

jrgordonsenior

Yea, if you change your clutch plates do a bunch of figure 8's, drive it for a few track sessions, and then change the diff oil. Makes a huge difference in performance especially with your new understeer....

GTgears

On the Quaife question? What's a good analogy? Would you take off your Michelin Pilots and install snow tires for a track day? Quaife TBDs aren't comparable to ANY LSD. It would be going backwards in performance.

por29

We always get good advise from Gaurd. We do quite a few OEM LSD diffs using Gaurd internals. They all have worked out great.

MetalSolid

My GT3 has 40k+ miles, and dare I say the diff feels fine.

To the original poster: I had the same issue as you at about 7k miles; the problem was the car had zero front-toe. You either want negative or positive static front-toe, never neutral, as under braking the tires want to toe out.

007DT

Wow... I may consider doing this. That's not bad at all.

Is this an install that can be done @ home? Scale of 1-10? (I have a lift @ my house)