dimok

"jerky" acceleration initially on 3rd gear, then also on second and 4th.

CarGuyNVA

Prior to my transfer case replacement, you would feel a clear occasional 'stutter' on acceleration particularly in 2nd and 3rd gears...It would cause a bump/shock like sensation through the drivetrain when the stutter would occur.

MountainStone

I took my Cayenne to the service department on 24 April and got it back today, 26 June. The entire delay was due to waiting for a transfer case. Last week I spoke with the Service Manager and Parts Manager and they referenced an email "from Germany" that stated Porsche had 138 transfer cases in stock and exactly one was due in to them last Thursday.

The 'stutter' was my symptom as well. Sounded like what you would expect to hear if you ran over several walnuts/acorns and crushed them under the tire.

termite01

"The 'stutter' was my symptom as well. Sounded like what you would expect to hear if you ran over several walnuts/acorns and crushed them under the tire."

Exactly the same symptom as mine. Failure at about 30k; replaced under CPO. PTV+ diff went at about the same time and was also replaced under CPO.

bweSteve

Hmmm, what were the symptoms of the PTV differential?

I have PTV (&PDCC), and I have 47k miles now (on my 2012).

=Steve

deilenberger

To summarize the symptoms:

• "Shudder/stutter" or "Jerky" acceleration in 2nd and/or 3rd gear
• Noise - cracking noise when turning

Is this correct?

Just as a sidenote - the noise when turning is the identical symptom a clutch based limited slip differential will give when a non-limited slip oil is used in it. The sound is the clutch plates sticking and releasing (binding). You can also feel this when turning - much like the jerky acceleration noted. GM makes an additive - spec'd for the Corvette - that cures this. I used it in a BMW E28/535 where I experienced this after changing the differential fluid. And that makes me think about Porsche recently changing the PN on the transfer-case fluid. Wonder what the change really was...? (Just mind-gaming here..)

bweSteve

Ahh, Thanks Don. I had my TC replaced {good will} about 2k miles ago, but I am now feeling this differential studder on low speed turns.

Thanks for helping clarify, as it seems I have,... had two different symptoms at the same time.

Guess it's back into the dealership. Wonder if they'll do a good will on the Diff too? (I'm out of warranty) ... or maybe I just need a Diff oil change. We'll see.

=Steve

deilenberger

AFAIK, our differentials aren't limited slip unless you get PTV (torque-vectoring) where they are limited slip electrically controlled. And there have been some issues with those ones.

termite01

The symptoms for my PTV+ diff failure were very similar to the TC failure but more vibration when turning left at low speeds. I could also hear a groaning noise at low speeds. The dealer at first though that the brand new TC was bad [!] but after placing microphones under the truck decided that it was the diff. When they drained the fluid out it was totally burnt. The service manager's view was that up until the most recent software update, the PTV+ was working all of the time but now only activates over 5 or 10 mph. This may have led to premature wear that really seems to effect PTV+ diffs. Pretty good size job to change it out and I am glad that I did not have to pay for it.....

bweSteve

Thanks termite01. Yea I'm experiencing the same symptoms.

We have multiple Diff's,... so when you say "PTV Diff", is it specifically one differential in particular?

Since I have a brand new TC, I am definitely thinking this is my PTV Differential.

=Steve

termite01

The issue was with the rear diff. I have only seen mention of one front diff having been replaced but several rears. All were PTV....willing to wager that almost all of the PTV rear diffs are likely to fail. There are not a lot of PDCC/PTV 958 TT's around and there seem to be a significant number that are having diff issues. Mine had 30k miles and was driven for 29k miles by a hausfrau who probably never went over 60 MPH. All dealer service and CPO as well. No reason for that diff to have gone and eaten itself....

bweSteve

Copy That termite01. Thanks for the clarification.
{< ... btw, I wasn't really thinking that my PDCC/PTV 958 CTT was all that rare due to options but maybe so... >}

I've been running the **** outta mine since I bought it with 16k miles 2.5 yrs ago. Autocross, towing, etc. I've got 47k miles on it now,.. so if it requires a rear PTV oil change, then I am more than FINE with that. If they tell me the rear diff is toast, ... well then we have a nice little conversation.

Sidebar: Sorry for tangent on rear PTC Diff (verses TC failure on this thread). I could not find a separate dedicated RL Thread for rear differential failures. Although I did find this thread on changing Diff oil...
https://rennlist.com/forums/cayenne-...ntial-oil.html

=Steve

CarGuyNVA

Mine had both symptoms, but they went away after my recent TC replacement (PTV+ equipped also).

As mentioned, the rear diff on the PTV+ Cayennes is an electronically controlled locking unit. The occasional chatter on tight low speed turns could be due to whatever Porsche uses in the fluid for a limited slip additive, wearing out/getting contaminated. Used to happen often on my GM performance vehicles with limited slip/locking diffs.

GM used to specify the small bottle of their limited slip additive, but in recent years specified a new synthetic axle lubricant that already includes an additive for the limited slip clutch plates. I'm guessing Porsche fluid is similar.

Dion Houng-Lee

I have both symptoms with cracking nuts on left turn and stutter on 2-3gear slow acceleration from a coast. Took it in yesterday and waiting to see what happens. Only 1 month out of CPO but dealer said they would fix under good will.

11' TT loaded with PDCC, PASM, PTV, etc.

g8tor20

I take it this is the fluid that some of you have used?