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I would never ever use a sprung disc on a 6Cup. The sprung disc is much less durable and will put more wear and tear on the synchros due to the increase in the MOI of the nearly twice heavier sprung street disc compared to the lightweight 4 puck disc. You will notice this when the gearbox gets very hot on extended sessions and becomes a bit "crunchy" during fast shifts. The sprung street disc is also slightly thicker than the Cup 4 puck disc which will move the engagement point down closer to the floor on the pedal stroke. The clutch throw effectively becomes longer with the street disc effectively slowing down the shift a bit. If you used a clutch stop before, you will need to remove it when using the street disc in order to get full disengagement during shifts. Honestly, installing the sprung street disc is not a great idea but doable if you are aware of the shortcomings that come with it. Yes, paddock behavior will be better but is that really that important? Just my $0.02 of course.
The 4 puck disc is available directly from Sachs. It's not expensive and nearly bullet proof. The 996Cup flywheel part number you were asking about is 964.102.239.81
This is EXACTLY what is happening with my car. I did have a pedal stop and it had to be removed. I also noticed 3rd gear shifts crunching when they didn’t before resulting in me having to slow that shift a little. Apart from that it felt fine, but I was surprised as to why a sprung disc was put in. I’m not sure if it’s the slightly lighter cup flywheel that has been fitted or the 996 Clubsport/rs flywheel that was used. Is the sold cup disc compatible with both of these flywheels?
Also @powdrhound would you recommend the original Sachs disc or the Kennedy disc? Would you happen to have the part no. for the Sachs disc? I understand the Kennedy disc is quite cheap. Then there is the option of 6 puck vs 4 - does that make a difference?
I thought I was looking at an earlier than expected gearbox rebuild but the crunching was not an issue with the twin plate. The paddock behaviour was a welcome surprise however, it’s not of huge importance to me - the twin plate was horrible in that regard and that never bothered me.
This is EXACTLY what is happening with my car. I did have a pedal stop and it had to be removed. I also noticed 3rd gear shifts crunching when they didn’t before resulting in me having to slow that shift a little. Apart from that it felt fine, but I was surprised as to why a sprung disc was put in. I’m not sure if it’s the slightly lighter cup flywheel that has been fitted or the 996 Clubsport/rs flywheel that was used. Is the sold cup disc compatible with both of these flywheels?
Also @powdrhound would you recommend the original Sachs disc or the Kennedy disc? Would you happen to have the part no. for the Sachs disc? I understand the Kennedy disc is quite cheap. Then there is the option of 6 puck vs 4 - does that make a difference?
I thought I was looking at an earlier than expected gearbox rebuild but the crunching was not an issue with the twin plate. The paddock behaviour was a welcome surprise however, it’s not of huge importance to me - the twin plate was horrible in that regard and that never bothered me.
The crunching is a result of the synchros not able to deal with the much MOI of the much heavier solid sprung disc. If you install the lightweight 4 puck disc, your issues will be gone. The sprung disc you have in there is almost 2.5X heavier than the 4 puck disc which has most of the weight near the hub to boot. The sprung disc is also significantly weaker and will have issues long term dealing with the driveline shock an aggressively driven car on slicks will impart on it. It's the wrong part for a race car application.
I don't know anything about a Kennedy disc. I see no reason to use that when a genuine Sachs race disc is available for under $400. Here is the Sachs 4 puck race disc. Same disc as the 996Cup disc without the Porsche part number. This is the disc I ran in my race car an it was bullet proof. I used this in conjunction with a 996Cup flywheel and the Sachs race 487 pressure plate which is just a beefed up Cup pp.
@powdrhound Thanks for all of the info! I’m a bit annoyed that the gearbox is going to have to come out again but this sprung disc is going to do more damage in short order by the sounds of it. I’m assuming that this Sachs disc will work with both the Clubsport flywheel as well as the 964/996 cup flywheel. From memory the swept area is the same on both just with a bit more lightening near the centre of the cup flywheel.
@powdrhound Thanks for all of the info! I’m a bit annoyed that the gearbox is going to have to come out again but this sprung disc is going to do more damage in short order by the sounds of it. I’m assuming that this Sachs disc will work with both the Clubsport flywheel as well as the 964/996 cup flywheel. From memory the swept area is the same on both just with a bit more lightening near the centre of the cup flywheel.
I honestly have no idea what a Clubsport flywheel is that you are referring to. The only LWFWs Porsche had made are the 964RS (964.102.239.31) and the 996Cup (964.102.239.81). The .31 was used in various models up through the 997.2GT3RS while the .81 was used in the 996Cup, 997.2GT3RS 4.0, and the 997GT2RS. Both the .31 and .81 are the same part but the .81 has more material machined away from the perimeter of the flywheel to further reduce the weight and MOI. The .31 weighs 11 lbs while the .81 is 9 lbs.
I have use the 996 cup PP and the same 4-puck disc shown above in my 964 for years now, together with the 964 cup/RS flywheel as referred to above. Works great! The clutch is a bit on/off but that's the whole point with this clutch. Love it on the track!
I honestly have no idea what a Clubsport flywheel is that you are referring to. The only LWFWs Porsche had made are the 964RS (964.102.239.31) and the 996Cup (964.102.239.81). The .31 was used in various models up through the 997.2GT3RS while the .81 was used in the 996Cup, 997.2GT3RS 4.0, and the 997GT2RS. Both the .31 and .81 are the same part but the .81 has more material machined away from the perimeter of the flywheel to further reduce the weight and MOI. The .31 weighs 11 lbs while the .81 is 9 lbs.
By Clubsport I am referring to the .31. It was used in the 996.1 GT3 Clubsport and 996.2 GT3RS road cars. Incorrect nomenclature from me since they all originated from the 964 but hey, I’m biased towards 996 at heart! That was my thought regarding the difference between .31 and .81 based on reading rennlist over the years - thanks for confirming the part numbers.
By Clubsport I am referring to the .31. It was used in the 996.1 GT3 Clubsport and 996.2 GT3RS road cars. Incorrect nomenclature from me since they all originated from the 964 but hey, I’m biased towards 996 at heart! That was my thought regarding the difference between .31 and .81 based on reading rennlist over the years - thanks for confirming the part numbers.
Gotcha. The .31 and .81 are both 100% interchangeable.
04-18-2024, 08:31 PM
