Porsche refuses LSD repair under warranty
06-01-2011, 03:52 PM
#76
Racer
Join Date: Dec 2009
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06-01-2011, 04:24 PM
#77
Nordschleife Master
From PET, courtesy of the fine folks at DC Automotive:
http://dcauto.gotdns.com:4000/illust...index/45232636
You are looking at the remnants of parts 3,4 and 5. I want to start by saying that I don't think this particular failure is in any way a result of inadequate materials or design on the part of Porsche. I think this happened because one of the carrier bearings was damaged in installation. After we rebuilt the unit, it was sent to a shop who replaced the bearings and installed the unit. The shop is not a GT dealer and was someone the car owner wanted to use local. As such I will not name names. It's not my place.
So, with the bearing damaged, I speculate that there was free play inside of the body and the stub axle flange levered itself against the splines on the backside of the drive gear (Big #5 in the picture just in from #4 the Cups aka Ramps.). It broke open, putting the teeth out of alignment, which then took out the teeth of the 4 spider gears (small #5 in center of picture). This was in an auto-x environment and it's possible that the wheel was lifted in a tight turn and slammed back to the ground. With the already compromised bearing, it couldn't take that load. But the tool marks on the bearing, which I have, suggest the bearing was damaged when first installed and that the damage went out from there.
At this point, the diff became a spool and would fight any attempt to turn the car, though it would drive perfectly straight. Upon disassembly it doesn't appear that any schrapnel got free of the diff body and our brand new clutch kit that was installed last month was undamaged. We're going to rebuild it with our gears and put a new bearing on it. Everything else appears to be fine.
http://dcauto.gotdns.com:4000/illust...index/45232636
You are looking at the remnants of parts 3,4 and 5. I want to start by saying that I don't think this particular failure is in any way a result of inadequate materials or design on the part of Porsche. I think this happened because one of the carrier bearings was damaged in installation. After we rebuilt the unit, it was sent to a shop who replaced the bearings and installed the unit. The shop is not a GT dealer and was someone the car owner wanted to use local. As such I will not name names. It's not my place.
So, with the bearing damaged, I speculate that there was free play inside of the body and the stub axle flange levered itself against the splines on the backside of the drive gear (Big #5 in the picture just in from #4 the Cups aka Ramps.). It broke open, putting the teeth out of alignment, which then took out the teeth of the 4 spider gears (small #5 in center of picture). This was in an auto-x environment and it's possible that the wheel was lifted in a tight turn and slammed back to the ground. With the already compromised bearing, it couldn't take that load. But the tool marks on the bearing, which I have, suggest the bearing was damaged when first installed and that the damage went out from there.
At this point, the diff became a spool and would fight any attempt to turn the car, though it would drive perfectly straight. Upon disassembly it doesn't appear that any schrapnel got free of the diff body and our brand new clutch kit that was installed last month was undamaged. We're going to rebuild it with our gears and put a new bearing on it. Everything else appears to be fine.
06-01-2011, 07:13 PM
#78
Three Wheelin'
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Matt-
My GT2 was the car that Champion installed your LSD a couple months back. After receiving the car, I wondered how long it would take to actually break in the clutch pack because it was horribly tight and made the car understeer everywhere. However, after last weekend at Road America with the Chicago region PCA the diff has finally started to back off the initial preload and life hasn't been better! I've got about 1000 miles on the diff now, probably 300 miles of track time at RA. Thanks for making a good product!
My GT2 was the car that Champion installed your LSD a couple months back. After receiving the car, I wondered how long it would take to actually break in the clutch pack because it was horribly tight and made the car understeer everywhere. However, after last weekend at Road America with the Chicago region PCA the diff has finally started to back off the initial preload and life hasn't been better! I've got about 1000 miles on the diff now, probably 300 miles of track time at RA. Thanks for making a good product!
06-01-2011, 08:07 PM
#79
Nordschleife Master
Nick,
You are welcome. Paul Guard used to tell people 5 heat cycles to break it in and bring it down to where it's going to be for the duration of use. Given how much mixed used, I tell people about 1000 miles. Now it's time to change your gear oil.
Then, going forward, change it every 15,000 miles, counting a weekend at the track as around 2500 miles.
Here's pictures of the other GT2 LSD I told you was out East at Mike B's. shop. Looks a lot like the one I told you about this morning. This is from a track driven GT2 that's pretty stock. To my knowledge this is the first time the gearbox has been apart. You can see the stack down in the bottom of the frame and that it was still on brass clutches and didn't have GT parts inside of it.
You are welcome. Paul Guard used to tell people 5 heat cycles to break it in and bring it down to where it's going to be for the duration of use. Given how much mixed used, I tell people about 1000 miles. Now it's time to change your gear oil.
Then, going forward, change it every 15,000 miles, counting a weekend at the track as around 2500 miles.
Here's pictures of the other GT2 LSD I told you was out East at Mike B's. shop. Looks a lot like the one I told you about this morning. This is from a track driven GT2 that's pretty stock. To my knowledge this is the first time the gearbox has been apart. You can see the stack down in the bottom of the frame and that it was still on brass clutches and didn't have GT parts inside of it.
