Tranny is out for LSD and 1st gear syncro rebuild. G Box says needs $10K of stuff
#32
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
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
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
#33
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
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.
![Wink](https://rennlist.com/forums/images/smilies/wink.gif)
Don't get me wrong - I did the housing measurement prior to rebuilding with cup parts.
#34
Admin
Lifetime Rennlist
Member
Lifetime Rennlist
Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
6GT3 diffs with the cup pack land in the 80ish Nm land..
It's not like one will be 10 and the other 200.. Now if you are talking 997 diffs I have no first hand data to back it up..but don't expect any major changes, Manthey still treats all diffs with the pre-2003 cup clutch pack so..
It's not like one will be 10 and the other 200.. Now if you are talking 997 diffs I have no first hand data to back it up..but don't expect any major changes, Manthey still treats all diffs with the pre-2003 cup clutch pack so..
#35
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Need to look for it(not at my place but in another garage). I know I wrapped it way back when. I did the 4.0 r/p back in late 2005 I had about 4-5k miles on it. Tell u what let me find it and I'll ship it to u provided if it looks fine to me. If your shop says it's find send me money later. How much they quote you on new r/p? I don't have a clue how much a new one costs. Mike
#37
Rennlist Member
Thread Starter
#38
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
My R&P are shot. That's $3,500 parts alone for new one from Germany. This car has 14K hard track miles. I was aware of the potnetial for this going in, but I got a great price on car otherwise.
#39
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
I guess this could still be more of an issue than just preload though:
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.
Well, at least I learned a little bit more about LSD's today as well.
#41
Rennlist Member
#42
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
I just sold two 3.44 ring and pinions - one with less than 4k street miles and the other with less than 8k street miles... I could have saved you some serious coin...
#43
Nordschleife Master
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
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.
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.
#44
Rennlist Member
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
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.
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.
Stock, I did feel the 2 to 3 especially dropped way off the revs, too big a gap.
I can't wait to drive the car!