GT4 Transmission Failure "Database"
11-06-2017, 12:05 AM
#376
Aftermarket LSD
An aftermarket LSD is unlikely to cause the type of 3rd gear failure we are seeing in the GT4 transmission. The output shaft is connected to the LSD and the failure of the 3rd gear is on the input shaft/driveshaft. Each gear comprises a set and the 3rd gear on the input shaft is friction welded whereas the 3rd gear on the output shaft is not. The friction weld on the 3rd gear on the input shaft is what is failing. One could argue that the differential places more force on the output shaft but there are many reasons why this is not the case with this type of failure.
Last edited by sportlife2012; 11-07-2017 at 02:56 AM.
11-06-2017, 01:42 PM
#378
Nordschleife Master
An aftermarket LSD cannot cause the type of 3rd gear failure we are seeing in the GT4 transmission. The output shaft is connected to the LSD and the failure of the 3rd gear is on the input shaft/driveshaft. In addition, each gear comprises a set and the 3rd gear on the input shaft is friction welded whereas the 3rd gear on the output shaft is not. The friction weld on the 3rd gear on the input shaft is what is failing. There are also many other engineering reasons but I trust this information helps.
For example, it's well known that the additional friction introduced by a performance LSD will raise gearbox tems 20-25 degrees F. Porsche's lawyer could argue in court that the extra heat compromised the welds and was causal to the failure. Your lawyer would have a hard time proving otherwise.
12-22-2017, 04:45 PM
#380
I'd like to add a little more data to the spreadsheet. How can I do that..
My car just lost the 3rd for the second time @ 12400mi. The first one was already captured by previous owner on the spreadsheet. It was listed as Omitted - 4100@ mi, Bay area. It was replaced w/ a BX P/N. Dealer just replaced the transmission with a CX. Crossing my fingers the CX holds up!
My car just lost the 3rd for the second time @ 12400mi. The first one was already captured by previous owner on the spreadsheet. It was listed as Omitted - 4100@ mi, Bay area. It was replaced w/ a BX P/N. Dealer just replaced the transmission with a CX. Crossing my fingers the CX holds up!
12-24-2017, 06:16 PM
#382
I'd like to add a little more data to the spreadsheet. How can I do that..
My car just lost the 3rd for the second time @ 12400mi. The first one was already captured by previous owner on the spreadsheet. It was listed as Omitted - 4100@ mi, Bay area. It was replaced w/ a BX P/N. Dealer just replaced the transmission with a CX. Crossing my fingers the CX holds up!
My car just lost the 3rd for the second time @ 12400mi. The first one was already captured by previous owner on the spreadsheet. It was listed as Omitted - 4100@ mi, Bay area. It was replaced w/ a BX P/N. Dealer just replaced the transmission with a CX. Crossing my fingers the CX holds up!
01-12-2018, 10:43 PM
#383
Intermediate
Join Date: Feb 2004
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Another entry for the database.
Shifted into 3rd at 6K rpm, then the revs climbed to near redline, and dropped to idle. During this the dash flashed 1st and 5th gear. There was no pop or grinding, but just a disengagement.
9,500 miles and no track time.
No modifications.
6/16 build
Dealer ordered the 1 remaining transmission sitting in Atlanta. CX part number and shipped overnight.
Dropped the car off on Monday and got it back on Friday.
Shifted into 3rd at 6K rpm, then the revs climbed to near redline, and dropped to idle. During this the dash flashed 1st and 5th gear. There was no pop or grinding, but just a disengagement.
9,500 miles and no track time.
No modifications.
6/16 build
Dealer ordered the 1 remaining transmission sitting in Atlanta. CX part number and shipped overnight.
Dropped the car off on Monday and got it back on Friday.
03-14-2018, 02:15 PM
#384
Advanced
Join Date: Mar 2015
Location: Perth, Western Australia
Posts: 97
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Another entry for the database coming to you from down under in Australia.
Shifting up from 2nd, gear shifter engaged into 3rd but revs climbed to near redline, and dropped to idle as if it was in neutral or the clutch was engaged.
No out of place noises, now able to drive with 1,2, 4,5,6 as normal but if you put it into 3rd, the dash will show either 1 or 5 and rev out.
Just hit 11,500KM's with no modifications.
This was an 8/16 build.
Limped back to the dealership and awaiting an update
Shifting up from 2nd, gear shifter engaged into 3rd but revs climbed to near redline, and dropped to idle as if it was in neutral or the clutch was engaged.
No out of place noises, now able to drive with 1,2, 4,5,6 as normal but if you put it into 3rd, the dash will show either 1 or 5 and rev out.
Just hit 11,500KM's with no modifications.
This was an 8/16 build.
Limped back to the dealership and awaiting an update
03-28-2018, 10:23 AM
#386
Another entry for the database from Porsche homeland
Cayman 981 GT4, 06/2016, 6.850 km (4.250 miles), all stock, march 25 2018, first real ride of the season, sporty drive backroad, from 2nd to 3rd, in 3rd no gearing, all other gears work flawless, car in for waranty repair/exchange gearbox at the moment, Michelin Cup 2 on 20" stock,
Cayman 981 GT4, 06/2016, 6.850 km (4.250 miles), all stock, march 25 2018, first real ride of the season, sporty drive backroad, from 2nd to 3rd, in 3rd no gearing, all other gears work flawless, car in for waranty repair/exchange gearbox at the moment, Michelin Cup 2 on 20" stock,
Last edited by 911tac; 03-28-2018 at 10:27 AM. Reason: Forgot facts
03-28-2018, 11:42 PM
#387
Originally Posted by 911tac
Another entry for the database from Porsche homeland
Cayman 981 GT4, 06/2016, 6.850 km (4.250 miles), all stock, march 25 2018, first real ride of the season, sporty drive backroad, from 2nd to 3rd, in 3rd no gearing, all other gears work flawless, car in for waranty repair/exchange gearbox at the moment, Michelin Cup 2 on 20" stock,
Cayman 981 GT4, 06/2016, 6.850 km (4.250 miles), all stock, march 25 2018, first real ride of the season, sporty drive backroad, from 2nd to 3rd, in 3rd no gearing, all other gears work flawless, car in for waranty repair/exchange gearbox at the moment, Michelin Cup 2 on 20" stock,
03-30-2018, 01:51 PM
#388
Hello, news from the Porsche homeland:
Porsche has replaced the transmission within 2 days. Good service. Pretty sure they're well prepared and know the issue very well. Part-No. 981-300-020-CX. Porsche doesn't hand out any papers that state the transmission exchange.
Porsche has replaced the transmission within 2 days. Good service. Pretty sure they're well prepared and know the issue very well. Part-No. 981-300-020-CX. Porsche doesn't hand out any papers that state the transmission exchange.
03-30-2018, 04:08 PM
#389
Rennlist Member
Great news. Glad to hear the repair was taken care of in a timely manner.
05-11-2018, 04:26 PM
#390
1st Gear
Join Date: Apr 2016
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Mine failed on my first track day this year April 7. Accelerating in 3rd, then poof, redline. after a couple seconds of "what the heck was that", I realized it must just have happened to me. Had Porsche Roadside pick it up and bring dealer. Transmission was swapped and car returned to me in a little over a week. Very pleased with customer service and the turnaround. Had another track day 4/27 and everything seems perfect. My build date was march/April 2016. Vin 191919
Bone stock, running Cup 2's. Agate Grey, PCCB, LWBS
Bone stock, running Cup 2's. Agate Grey, PCCB, LWBS