2010 GT3RS- LSD Shot
05-26-2010, 04:35 PM
#32
Rennlist Member
certainly if there were no PCNA maintainence record that the diff had been eviscerated it would probably be a whole lot better than if such a record existed IMHO YMMV
05-26-2010, 04:51 PM
#33
Nordschleife Master
05-26-2010, 04:53 PM
#34
Rennlist Member
beats me ... call PMNA parts guy?
05-26-2010, 04:57 PM
#35
Addict
Rennlist Member
Rennlist Member
Porsche has been using the same design LSD for the GT3 transmission since 1999. Low quality brass plates.
Copans told me not to expect more than 2,000 track miles from my stock 996 GT3 LSD. Funny enough, the diff broke around 2,000 miles in my brand new 04 GT3 (it did not wear out, it broke). I got a new transmission under warranty. At 8,000 miles my diff wore out entirely. I had the option to keep using the stock junk or upgrade it and forfeit any warranty claims for the transmission. I chose to leave the transmission out of warranty, as any problem with the transmission could be fixed by Copans.
So, Copans installed a Porsche MotorSports LSD, he installed a 4.00:1 R&P and we put a new clutch with the LW flywheel. The LSD was trouble free for the next 28,000 miles (total of 34,000 miles) when I sold the car. I went through 2 stock diff in 8,000 miles, and not changing the way I drove my car one good diff lasted 28,000 miles plus the mileage on the 2-3 subsequent owners of the same car.
But as usual, the state of mind of self denial in plenty of GT3 track drivers tells them their diffs are fine. Most tracked GT3 are running open diff, it is difficult to notice it because the car is rear heavy, but once you get to drive near the limits, you will notice it immediately. Some drivers just soften the rear sway bar because the stiff setting makes their cars a little jerky on turn entry and turn exit, there are other ways to mask a worn-out LSD, such as stiffening the front bar, changing braking style, but at the end these are ways to mask a mechanical defect.
Copans told me not to expect more than 2,000 track miles from my stock 996 GT3 LSD. Funny enough, the diff broke around 2,000 miles in my brand new 04 GT3 (it did not wear out, it broke). I got a new transmission under warranty. At 8,000 miles my diff wore out entirely. I had the option to keep using the stock junk or upgrade it and forfeit any warranty claims for the transmission. I chose to leave the transmission out of warranty, as any problem with the transmission could be fixed by Copans.
So, Copans installed a Porsche MotorSports LSD, he installed a 4.00:1 R&P and we put a new clutch with the LW flywheel. The LSD was trouble free for the next 28,000 miles (total of 34,000 miles) when I sold the car. I went through 2 stock diff in 8,000 miles, and not changing the way I drove my car one good diff lasted 28,000 miles plus the mileage on the 2-3 subsequent owners of the same car.
But as usual, the state of mind of self denial in plenty of GT3 track drivers tells them their diffs are fine. Most tracked GT3 are running open diff, it is difficult to notice it because the car is rear heavy, but once you get to drive near the limits, you will notice it immediately. Some drivers just soften the rear sway bar because the stiff setting makes their cars a little jerky on turn entry and turn exit, there are other ways to mask a worn-out LSD, such as stiffening the front bar, changing braking style, but at the end these are ways to mask a mechanical defect.
05-26-2010, 05:17 PM
#36
Nordschleife Master
I don't have an account with PMNA. I don't have any need for one. We're a competing parts manufacturer. I was just curious since it used to be something silly like $1600 for just the plates, discs and bell. washers.
Though they've been known to buy from us on occasion since our early Cup Car gears actually carry Porsche part numbers. When the sequential gearbox was first released, we were the OEM.
Though they've been known to buy from us on occasion since our early Cup Car gears actually carry Porsche part numbers. When the sequential gearbox was first released, we were the OEM.
05-26-2010, 05:29 PM
#37
do you mind elaborating a little on how the diff "broke"? the stock internals of my diff had BENDS in them, specifically the metal "tabs" were bent upward 90deg, literally deformed metal pieces (the bell. washer i believe it was?). PCNA denied warranty coverage but many "experts" felt it was a install issue when teh dealer rebuilt the diff the first time with stock parts. they denied warranty the 2nd time.
just curious to hear about what your diff looked like when it broke, thanks!
just curious to hear about what your diff looked like when it broke, thanks!
Porsche has been using the same design LSD for the GT3 transmission since 1999. Low quality brass plates.
Copans told me not to expect more than 2,000 track miles from my stock 996 GT3 LSD. Funny enough, the diff broke around 2,000 miles in my brand new 04 GT3 (it did not wear out, it broke). I got a new transmission under warranty. At 8,000 miles my diff wore out entirely. I had the option to keep using the stock junk or upgrade it and forfeit any warranty claims for the transmission. I chose to leave the transmission out of warranty, as any problem with the transmission could be fixed by Copans.
So, Copans installed a Porsche MotorSports LSD, he installed a 4.00:1 R&P and we put a new clutch with the LW flywheel. The LSD was trouble free for the next 28,000 miles (total of 34,000 miles) when I sold the car. I went through 2 stock diff in 8,000 miles, and not changing the way I drove my car one good diff lasted 28,000 miles plus the mileage on the 2-3 subsequent owners of the same car.
But as usual, the state of mind of self denial in plenty of GT3 track drivers tells them their diffs are fine. Most tracked GT3 are running open diff, it is difficult to notice it because the car is rear heavy, but once you get to drive near the limits, you will notice it immediately. Some drivers just soften the rear sway bar because the stiff setting makes their cars a little jerky on turn entry and turn exit, there are other ways to mask a worn-out LSD, such as stiffening the front bar, changing braking style, but at the end these are ways to mask a mechanical defect.
Copans told me not to expect more than 2,000 track miles from my stock 996 GT3 LSD. Funny enough, the diff broke around 2,000 miles in my brand new 04 GT3 (it did not wear out, it broke). I got a new transmission under warranty. At 8,000 miles my diff wore out entirely. I had the option to keep using the stock junk or upgrade it and forfeit any warranty claims for the transmission. I chose to leave the transmission out of warranty, as any problem with the transmission could be fixed by Copans.
So, Copans installed a Porsche MotorSports LSD, he installed a 4.00:1 R&P and we put a new clutch with the LW flywheel. The LSD was trouble free for the next 28,000 miles (total of 34,000 miles) when I sold the car. I went through 2 stock diff in 8,000 miles, and not changing the way I drove my car one good diff lasted 28,000 miles plus the mileage on the 2-3 subsequent owners of the same car.
But as usual, the state of mind of self denial in plenty of GT3 track drivers tells them their diffs are fine. Most tracked GT3 are running open diff, it is difficult to notice it because the car is rear heavy, but once you get to drive near the limits, you will notice it immediately. Some drivers just soften the rear sway bar because the stiff setting makes their cars a little jerky on turn entry and turn exit, there are other ways to mask a worn-out LSD, such as stiffening the front bar, changing braking style, but at the end these are ways to mask a mechanical defect.
05-26-2010, 05:38 PM
#38
Nordschleife Master
ex10psi,
There was a manufacturing issue with some of the early 996 GT3 LSDs. They broke the "rim" off the body of the "hat". It was generally a catastrophic failure. I can't speak to NJ-GT's failure, but that was the most common failure. There should be some pictures around here if you search. I know Joel Reiser has posted them before over on Pelican.
There was a manufacturing issue with some of the early 996 GT3 LSDs. They broke the "rim" off the body of the "hat". It was generally a catastrophic failure. I can't speak to NJ-GT's failure, but that was the most common failure. There should be some pictures around here if you search. I know Joel Reiser has posted them before over on Pelican.
05-26-2010, 05:55 PM
#39
Addict
Rennlist Member
Rennlist Member
do you mind elaborating a little on how the diff "broke"? the stock internals of my diff had BENDS in them, specifically the metal "tabs" were bent upward 90deg, literally deformed metal pieces (the bell. washer i believe it was?). PCNA denied warranty coverage but many "experts" felt it was a install issue when teh dealer rebuilt the diff the first time with stock parts. they denied warranty the 2nd time.
just curious to hear about what your diff looked like when it broke, thanks!
just curious to hear about what your diff looked like when it broke, thanks!
When it broke, I felt a metallic sound like hitting a rolling wheel with a hammer. The car was still driveable, but it was pulling hard to left under acceleration and hard to the right under deceleration. I drove it to the dealer just like that.
My dealer told me I got a defective transmission, that was it. All the gears were fine.
Copans has told me that the stock LSD housing is pretty strong, not as nice and strong as the Guard LSD, but good enough. It is the internals in the stock LSD what's really crappy.
05-26-2010, 10:12 PM
#41
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I just got back from the shop today with a repaired stock LSD. A shim busted in two pieces and left the LSD open. The oem friction discs are apparently very new looking....been driving that way for a while I guess.
Tim: If you are curious, get Steve P to drive your car at a Bullet track day. He drove my car and said the LSD was gone. He was right!
Tim: If you are curious, get Steve P to drive your car at a Bullet track day. He drove my car and said the LSD was gone. He was right!
05-26-2010, 10:53 PM
#42
Drifting
Thread Starter
Bad heel-toe downshifts and spins without both feet in certainly don't add to the longevity of diffs, trannys, clutches, gears and axles.
Hard to truly believe that lsds last for such a short duration without contributing factors.......particularly in GT-3s - cup or street.
Hard to truly believe that lsds last for such a short duration without contributing factors.......particularly in GT-3s - cup or street.
I missed getting a ride with you in the Cup and Ted in the RS, you guys both skipped out on your 2nd day runs. Next time ok? I want to see the fast guys in action.
05-27-2010, 12:01 AM
#43
05-27-2010, 12:02 AM
#44
Rennlist Member
Just curious as I have owned 5 996 GT-3s and have easily put many, many thousands of track miles on them and have had absouletly no issues with the diffs. And I have had plenty of pros drive these cars with never a mention of any problem with a diff. Same as to the 2 GT-2s I have owned, including the last one that has over 650hp with many track miles (I think it is the same tranny as GT-3s, but not sure). Perhaps I have been lucky.....Can't say the same things as to SPBOX - with open and closed diffs. We had had problems with those. And I also have owned a different brand vehicle with very high HP and had difficulties heel and toeing in it (pedal placement) and after some bad downshifts, the diff blew.
That said, I have heard very good things about the Guard diffs and certainly should be a good (and hopefully durable) upgrade.
One other area I would say to the group of dedicated trackers - replace halfshafts periodically - on the cups, we generally replace them after each season if lots of driving - they do give out and it would seem as though stronger diffs could put more loads on the axles??? I was lead to believe (perhaps erroneously), that the halfshafts are the "weaker" link in the whole drivetrain equation, and that certainly under racing conditions, it would be easier to replace axles than diffs/trannys??? Then again, I am the least technical person to speak of this and will defer to the experts.
BTW - RS coming in soon so anxious to see what it is like on the track. And come out again to SM - the 996 and 997 Cups are out there and happy to give you a ride! Not sure if it will be fast, but certainly fun...... And whatever Ted did at practice worked; he and Andy won at VIR!
05-27-2010, 12:20 AM
#45
Rennlist Member
But as usual, the state of mind of self denial in plenty of GT3 track drivers tells them their diffs are fine. Most tracked GT3 are running open diff, it is difficult to notice it because the car is rear heavy, but once you get to drive near the limits, you will notice it immediately. Some drivers just soften the rear sway bar because the stiff setting makes their cars a little jerky on turn entry and turn exit, there are other ways to mask a worn-out LSD, such as stiffening the front bar, changing braking style, but at the end these are ways to mask a mechanical defect.
The car was still driveable, but it was pulling hard to left under acceleration and hard to the right under deceleration.
The car was still driveable, but it was pulling hard to left under acceleration and hard to the right under deceleration.