Originally Posted by Serge944

The only thing the plate thicknesses change is the preload from the Belleville washers. It will always "fit."

Originally Posted by 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

Originally Posted by CanyonBlaster

!!! Mike - how many miles on it? what shape is it in? Do u wanna sell it? How much $??

Originally Posted by 911SLOW

If Mike can't find it I have one too.

Originally Posted by mikymu

Something is not right here. $10K for tranny rebuild = $500 per hour labor rate. Parts along should be no more than couple grand. My Cup tranny was completely rebuild for much less than $10K

Originally Posted by Serge944

Isn't that what I said in 1 sentence? When you're rebuilding with OE parts, your preload will vary from diff to diff.

Don't get me wrong - I did the housing measurement prior to rebuilding with cup parts.

Originally Posted by GTGears

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.

Originally Posted by 996FLT6

A stock r/p costs that much? It's only 2 pieces. U could fit it in a size 18 shoebox. Mike

Originally Posted by FFaust

OP, not sure what your plan is at the moment, but make sure that you take a serious look at the gearing, ratios, that is. Now is the time, if ever.

I just installed a 2002 cup box in mine (actually the innards, as I kept my housing), and although it's not earth-shattering, it is "just right". It's the way the gearing should have been all along. Spacing is perfect, and the car is EASIER to drive everywhere. Car no longer feels as much of a momentum car, and when I get a point-by, I can usually get the job done before the next corner.

Good luck.