Transfer case
09-12-2018, 06:45 PM
#496
Pro
Just a quick thought. Porsche’s recommendation of much higher pressures for the rear tires vs the front,, coupled with the lower weight on rear vs front, is going to create a slight imbalance front to rear in terms of rolling radius. Wonder if this is contributing. May be a bigger factor than tire wear...
09-12-2018, 11:19 PM
#497
Banned
Join Date: Mar 2011
Location: Spring Lake, NJ, US of A
Posts: 10,085
Received 1,141 Likes
on
758 Posts
Just wanted to add some feedback that I found out recently.
Been speaking to a couple of independents and a local Porsche center (the techs themselves) about the drivetrain and the various issues the 958 has. My car has had the TC replaced and I am paranoid about having it go bad again (out of warranty unfortunately) and I was keen to figure out preventative measures. Clearly regular checks on the fluid and the updated vent tube etc is a great thing to do. But one thing that I noticed before here (can't find the post), but its worth raising up again though - everyone seems to be focusing in on tire wear and consistency. Everyone I spoke to seems to think that some of the drivetrain issues 'could' be related to uneven wear of the tires. Seems that its very sensitive to uneven wear and this can cause excessive wear on key components in the drivetrain as a whole (including the TC). I know the common advice from Porsche centers is to replace all 4 tires and brakes at the same time, but as the cars age and pass to second and third owners, many don't do this which could accelerate the deterioration of the components.
Is there evidence on this? Not really, but worth considering if anyone is suffering or worried about the TC (and differentials) - best to replace tires all at the same time and keep things consistent. If anyone has anything specific though - please do share. But this seems to be the advice that I am getting.
Been speaking to a couple of independents and a local Porsche center (the techs themselves) about the drivetrain and the various issues the 958 has. My car has had the TC replaced and I am paranoid about having it go bad again (out of warranty unfortunately) and I was keen to figure out preventative measures. Clearly regular checks on the fluid and the updated vent tube etc is a great thing to do. But one thing that I noticed before here (can't find the post), but its worth raising up again though - everyone seems to be focusing in on tire wear and consistency. Everyone I spoke to seems to think that some of the drivetrain issues 'could' be related to uneven wear of the tires. Seems that its very sensitive to uneven wear and this can cause excessive wear on key components in the drivetrain as a whole (including the TC). I know the common advice from Porsche centers is to replace all 4 tires and brakes at the same time, but as the cars age and pass to second and third owners, many don't do this which could accelerate the deterioration of the components.
Is there evidence on this? Not really, but worth considering if anyone is suffering or worried about the TC (and differentials) - best to replace tires all at the same time and keep things consistent. If anyone has anything specific though - please do share. But this seems to be the advice that I am getting.
What I have seen on photos of disassembled Cayenne transfer cases is rust on the clutch disk fingers where they transfer power to the clutch hub and the clutch cage. I think that's probably the biggest cause of failure. Once the plates don't engage correctly they'll start wearing rapidly and bobs your uncle - you've got a bad transfer case. I think regular fluid changes and the vent kit for the transfer case will go a long way toward making the cases last.
09-13-2018, 12:13 AM
#498
I know that different tire sizes front and rear may render your case ground up beyond repair. I'd be disappointed to think a few mm's difference tread was enough to cause this, but anything is possible. I note that some owners are not reporting the issue. Too bad we aren't modifying some pickup truck case to work 
09-13-2018, 08:47 PM
#499
My son has had two Subarus over the years. He was advised by the dealer to always replace all four tires at the same time to protect the drive line. Following this recommendation he had no drive line issues.
09-20-2018, 03:52 AM
#501
Rennlist Member
same vent line here 1500 miles with one small issue , in Sport+ mode while slowly position the car in my garage and just before stop there is a big clunk sound and feel from the transfer case area. i do not recall the original case did that.
09-20-2018, 02:37 PM
#502
2013 GTS w/ PTV+ & PDCC exhibiting TC issues specifically on down shifts into 2nd/3rd. Its like it just drops the clutch and doesn't match revs... This morning I had a spell where the revs raced with no accel then shifted into 2nd and the car takes off. Sigh...
09-20-2018, 03:25 PM
#503
RL Community Team
Rennlist Member
Rennlist Member
Fluid change time!
09-22-2018, 08:24 PM
#505
Instructor
Join Date: Sep 2004
Location: Rochester, MN
Posts: 186
Likes: 0
Received 0 Likes
on
0 Posts
So far, 3000 miles, no issues. Fingers crossed.
09-22-2018, 09:50 PM
#506
Drifting
Yeah 3000 miles....piece of cake. Wait till you get at least 30k on the new one before you start partying. My previous CTT had its first replacement around 32k miles, and the second one just after 60k. The one put in at the 60k replacement was the latest version TC along with the vent kit, etc. I traded it about 12k miles after that, so I’ll never know how that new one holds up over time....but hopefully it goes longer than another 30k!
(BTW, my CTT was never used for towing, never tracked, not driven overly aggressive on the street, and never driven through deep water....in fact not even driven much when it rained)
Best of luck with yours though, sincerely. I hope Porsche finally has this solved with the latest parts...it’s ridiculous.
(BTW, my CTT was never used for towing, never tracked, not driven overly aggressive on the street, and never driven through deep water....in fact not even driven much when it rained)
Best of luck with yours though, sincerely. I hope Porsche finally has this solved with the latest parts...it’s ridiculous.
09-22-2018, 10:27 PM
#507
Instructor
Join Date: Sep 2004
Location: Rochester, MN
Posts: 186
Likes: 0
Received 0 Likes
on
0 Posts
Yeah 3000 miles....piece of cake. Wait till you get at least 30k on the new one before you start partying. My previous CTT had its first replacement around 32k miles, and the second one just after 60k. The one put in at the 60k replacement was the latest version TC along with the vent kit, etc. I traded it about 12k miles after that, so I’ll never know how that new one holds up over time....but hopefully it goes longer than another 30k!
(BTW, my CTT was never used for towing, never tracked, not driven overly aggressive on the street, and never driven through deep water....in fact not even driven much when it rained)
Best of luck with yours though, sincerely. I hope Porsche finally has this solved with the latest parts...it’s ridiculous.
09-23-2018, 12:01 AM
#508
Rennlist Member
adaptation !
glad to hear , keep the post updated with the good news , there is hope for that latest version.
was scanning the invoice and had the chance to read it again, noticed the technician did adaptation reset twice ,as in the past few days that clunk just before stopping in sport+ is gone.
i have an iCarsoft POR II coming in the mail maybe i can reset adaptation again.
was scanning the invoice and had the chance to read it again, noticed the technician did adaptation reset twice ,as in the past few days that clunk just before stopping in sport+ is gone.
i have an iCarsoft POR II coming in the mail maybe i can reset adaptation again.
09-25-2018, 01:56 PM
#509
10-06-2018, 05:43 PM
#510
Banned
Join Date: Mar 2011
Location: Spring Lake, NJ, US of A
Posts: 10,085
Received 1,141 Likes
on
758 Posts
I've now gotten obsessed with creating surveys using Google Forms (cool tool!) - and I've created one for the transfer case failures. I think I have everything covered in it - but if there are suggestions or errors spotted - fire away.
It can be found at: https://goo.gl/forms/fF75xsoM24nuLVhE2 - and it might take about 5 minutes to fill in (worst case)
TIA for giving it a shot!
It can be found at: https://goo.gl/forms/fF75xsoM24nuLVhE2 - and it might take about 5 minutes to fill in (worst case)
TIA for giving it a shot!