SW GT3 3.9L
07-18-2011, 11:44 PM
#107
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Well, lest my sense of humor be misinterpreted, I'll start off by saying, no sarcasm, full points to Alex and the Sharkwerks guys for listening to the driver. If you're currently at a couple of days on the track from year to year, maybe you'll never see the light (sorry, there's my idea of wit creeping in) but maybe you'll "grow some" (again, sorry) and then you'll plug in the LSD. But I can't make that decision for you and certainly, nor can the company selling the track gear.
07-19-2011, 01:13 AM
#108
Rennlist Member
I'm curious to know the cost and the options. Is it still possible to "rebuild" the Porsche gears with a Guard LSD pack? Is that failure prone? I recall it costing considerably more to replace the planetary gear assembly with the "complete" Guard assembly, but the benefit is meant to be "bullet proof" strength.
Perhaps Matt can chime in and point to a previous post/answer on this topic or maybe you have the details?
Price is also relevant, especially in terms of reversing the process since I want to keep the hardware for the next car if that's a financially viable route.
Perhaps Matt can chime in and point to a previous post/answer on this topic or maybe you have the details?
Price is also relevant, especially in terms of reversing the process since I want to keep the hardware for the next car if that's a financially viable route.
Mine cost $1,600 w/o labor to remove and install the diff. Hope this helps
07-19-2011, 03:00 AM
#109
I'll try to help out. I had my LSD rebuilt by Matt. Champion sent the OEM case to GT, and they replaced it with their clutches and ramps. You can get it done without ramps and keep the stock locking ratio (28/40) or put new ramps and increase the percentages. The difference between the two options was $650.
Mine cost $1,600 w/o labor to remove and install the diff. Hope this helps
Mine cost $1,600 w/o labor to remove and install the diff. Hope this helps
If Porsche has 28/40, I'm not sure why Guard would go to 40/60 and I'm not at at all clear on how Porsche could assert that the factory LSD is achieving 28/40 when the clutch pack achieves zero pre-load and whatever friction surfaces are involved are eroded and gone within a matter of 1K or 2K track miles (at most.)
07-19-2011, 07:27 AM
#110
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Interesting. Thanks. This is consistent with other information I've picked up. I'm not clear on exactly what's changed, but I have to suspect the factory "ramp" ratios are fictitious since those ramps and clutches don't have preload and don't work in the first place (at least, in my humble.)
If Porsche has 28/40, I'm not sure why Guard would go to 40/60 and I'm not at at all clear on how Porsche could assert that the factory LSD is achieving 28/40 when the clutch pack achieves zero pre-load and whatever friction surfaces are involved are eroded and gone within a matter of 1K or 2K track miles (at most.)
If Porsche has 28/40, I'm not sure why Guard would go to 40/60 and I'm not at at all clear on how Porsche could assert that the factory LSD is achieving 28/40 when the clutch pack achieves zero pre-load and whatever friction surfaces are involved are eroded and gone within a matter of 1K or 2K track miles (at most.)
In theory the LSD is preloaded by the diaphragm springs in the disk sets with a very low preload from the factory, (basic torque) so that it can be "ready" to work, without torque having to be applied.
When the car is moving, the expansion force acts on the disc sets and so the static friction moment produced by preloading them, is considerably increased.
However due to the soft disks provided with the oem LSD, this theory no longer applies after a few k miles, as the already low basic torque goes to almost zero Nm affecting the LSDs operation and the car's handling.
You can get a higher preload by using the steel friction-disk set from the cup cars. The installation procedure is same as per changing the oem disk set and any dealer can do it. (and perhaps they can cover the labor for a LSD rebuilt under warranty if you provide them the "factory" parts; It has been done before..)
Regarding the locking rates I think that Porsche went with milder locking rates for the 997 GT3s so that the LSD could coexist, and work more efficiently/smoothly, with the electronic aids.
BTW Porsche now runs 37/52% LSD in the cup cars and in the RSR, you can chose between a 45/65% or a 50/80% (*both RSR diffs use the same friction-disk set. )
08-05-2011, 07:40 PM
#112
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schweet!
08-05-2011, 07:48 PM
#113
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Thanks to the rennlist chatter we decided to outfit it with the Guard beefed-up LSD unit
08-05-2011, 08:10 PM
#114
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Another silver 3.9! Guess I'm not so special anymore! I just got back from a 600 mile trip north. My is running stronger then ever! I know the new owner will enjoy his drive home. Hope you guys got some good break in miles on it so he can have some fun. Hehe!
08-07-2011, 11:18 PM
#116
Instructor
Thread Starter
The new silver 3.9 owner definitely enjoyed the drive home...AFTER I was turned around on the 101s because of a fire and AFTER I turned around on the 152e for a highway closing accident. I was not a happy campler 3 hours and 80 miles into my drive home. I ended up on Highway 25 south. I made a left about 15 miles south of the town of Hollister onto Panoche Road....as in don't drive like a Panoche on my road! 40+ miles of great twists, bumps, and wide open, nobody for 10+ mile diameter straights. It was here, on Panoche Road, when I first realized the love I have for my new 3.9. I laughed out loud 17 times on the way home from there.
I can safely say that I now have one of the 14 baddest GT3's in the land. I will be reversing my vasectomy next week, and naming my family's next child Alex Ross Johnson....boy or girl.
I can safely say that I now have one of the 14 baddest GT3's in the land. I will be reversing my vasectomy next week, and naming my family's next child Alex Ross Johnson....boy or girl.
08-07-2011, 11:33 PM
#118
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The new silver 3.9 owner definitely enjoyed the drive home...AFTER I was turned around on the 101s because of a fire and AFTER I turned around on the 152e for a highway closing accident. I was not a happy campler 3 hours and 80 miles into my drive home. I ended up on Highway 25 south. I made a left about 15 miles south of the town of Hollister onto Panoche Road....as in don't drive like a Panoche on my road! 40+ miles of great twists, bumps, and wide open, nobody for 10+ mile diameter straights. It was here, on Panoche Road, when I first realized the love I have for my new 3.9. I laughed out loud 17 times on the way home from there.
I can safely say that I now have one of the 14 baddest GT3's in the land. I will be reversing my vasectomy next week, and naming my family's next child Alex Ross Johnson....boy or girl.
I can safely say that I now have one of the 14 baddest GT3's in the land. I will be reversing my vasectomy next week, and naming my family's next child Alex Ross Johnson....boy or girl.
08-07-2011, 11:43 PM
#119
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08-08-2011, 02:44 PM
#120
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That's actually pretty funny... he took a 600mile trip south and you did 600 miles north. I think we have the Bear state covered now eh;I've always got more:P
The new silver 3.9 owner definitely enjoyed the drive home...AFTER I was turned around on the 101s because of a fire and AFTER I turned around on the 152e for a highway closing accident. I was not a happy campler 3 hours and 80 miles into my drive home. I ended up on Highway 25 south. I made a left about 15 miles south of the town of Hollister onto Panoche Road....as in don't drive like a Panoche on my road! 40+ miles of great twists, bumps, and wide open, nobody for 10+ mile diameter straights. It was here, on Panoche Road, when I first realized the love I have for my new 3.9. I laughed out loud 17 times on the way home from there.
I can safely say that I now have one of the 14 baddest GT3's in the land. I will be reversing my vasectomy next week, and naming my family's next child Alex Ross Johnson....boy or girl.
I can safely say that I now have one of the 14 baddest GT3's in the land. I will be reversing my vasectomy next week, and naming my family's next child Alex Ross Johnson....boy or girl.
Seriously though it was a real thrill for us as we don't do them too often:P I'm so glad you got try it out on that road... I have some fond memories there myself. I left a few bits of rubber there
Keep on laughing!Haha that'd be safer!
Actually James found a certain vacuum line from the distributor that wasn't hooked up to the carbs:P Runs like a champ now for a carb'd POS! She's a bit slower than Kermit tho... I need a 3.9 in that 2100pound 1971 yellow-banana.