I thought to open this thread to share and learn information about panamera transmission , its deffects ,upgrades ,tips and failures.

I found these interesting information about zf transmission on just-auto.com
First Platform

Program

Torque

Applications

7DT-45HL

500N.m

Porsche 911

7DT-45HLA

500N.m

Porsche 911 4-Wheel-Drive

7DT-45FL

500N.m

Porsche Boxster and Cayman

7DT-70HLA

780N.m

Porsche 911 Turbo

Second Platform

Program

Torque

Applications

7DT-75

500/780N.m

Porsche Panamera

7DT-75A

500/780N.m

Porsche Panamera 4-Wheel-Drive

One key benefit of the DCT is that any gear ratios can be specified to exactly match the requirements of the application/engine, unlike the automatic, where the ratios are largely fixed. In addition to allowing the desired ratio progression, this also allows the designers to increase the ratio spread,*
which reduces the engine speed when cruising and hence reduces CO2. For the first platform, for the sports car applications, ZF has several different ratio sets, with ratio spreads extending up to a very creditable 6.4. This has reduced the engine speed at 100km/h from 2450rpm to 1750rpm in the 911 Carrera, compared to the previous version. However, on the second platform for the Panamera, ZF and Porsche have decided on an even*wider ratio spread of 10.1, which exceeds the current highest example (the VW DL501), which has a ratio spread of 8.0.

On the 7DT75 for the Panamera, ZF has included a stop-start system, which allows the transmission to be ready as soon as the engine is restarted. As is common with many other stop-start systems on the market, the driver has the option to turn this function off. Unlike other similar systems, it does not rely on an electric oil pump to maintain the transmission oil pressure.
Instead, it uses a form of non-return valve, although ZF declined to go into any more detail. One clue lies in the claim that the transmission needs no oil pressure once the gear is selected, which also gives ZF the ability to offer a limp-home feature, should the electronic controller fail. Curiously, Porsche did not specify stop-start for the versions in the sports cars, although ZF claimed that there was no technical reason why this could not have been included.
All of the 7DT transmissions were developed (and successfully tested) to use a lifetime oil fill, but Porsche decided to err on the side of caution and opted for a 90,000km oil change interval. The hydraulic controller features pre-controlled or 'piloted' valves, which are supposedly less susceptible to oil contamination; some observers believe that these are somewhat old-fashioned now, having given way to direct-acting valves in many modern applications.

In terms of the oil circuit itself, two completely different approaches have*
been employed for the two platforms. The 7DT45 and 7DT70 have two oil circuits, and hence two different oils; the first is Pentosin FFL-3 for the clutch and hydraulics, and the second is ExxonMobil Mobilube PTX 75W-90 for the gear-set and bevel gear. The oil levels have been kept as low as possible, to reduce churning losses for those moving parts that are immersed in oil. Conversely, the 7DT75 has a single oil circuit and a dry sump (to minimise churning losses), with an 'active lubrication system' to feed oil to each gear-set and clutch. This version uses only the Pentosin FFL-3 lubricant, which was developed exclusively for the ZF DCTs. One of the main reasons for*using a single oil circuit is that clutch cooling is required at both ends of the transmission, for the main dual-clutch module and for the hang-on clutch used in the four-wheel-drive variant. This would have presented significant sealing complications had multiple circuits been chosen.

In addition, the 7DT75 is unusual in that the layshaft is mounted above the input shaft rather than below it. This was done to meet Porsche's requirement that the package should be 'narrow with a high tunnel', presumably so that the engine/transmission could be mounted lower in the chassis to give a lower centre of gravity for the vehicle.

All of the 7DT programs feature software with an adaptive shift strategy, which not only adjusts the shifting patterns according to the physical vehicle and road conditions (including mountain and road-surface sensing), but also monitors the way in which the car is being driven. So, in effect, they are monitoring the mood of the driver and will adjust the shift strategy accordingly. This kind of fuzzy logic has been used in the past, with mixed results, so it will be interesting to see how owners react to this latest implementation of the technology.

Driving Experiences
In terms of driving, the experience is very much like driving a standard automatic transmission, the main difference being that the shifts are considerably faster. Having said this, there is a noticeable delay between pressing one of the steering-wheel mounted switches and the shift being performed. The actual shift times are open to interpretation, as different people define shift time in different ways, but ZF is quoting times of about 400-500ms. In most cases, you only know that a shift has occurred because the engine revs drop and the*dashboard indicator changes. This compares to shift times of about 750ms in the previous versions using the Daimler 5-speed automatic.

In practice, in Comfort mode, the transmission changes gear almost imperceptibly, and in a way that does not distract the driver, so in this respect it achieves its goal. In the Sport mode, the shifts occur much later, allowing the engine to rev higher, for a more interactive and sporty feel. And in those vehicles in which the Sport Plus option is available, the driver has the ability to reduce shift quality in favour of performance, which results in a shift strategy that is probably only appropriate for track use. The Sport Plus mode also includes a launch control function, which allows the driver to build the engine speed to maximum before releasing the brake for an exceptionally quick getaway. When this happens, the transmission oil is circulated over the clutch much more quickly than normal, to prevent it from overheating.

 

If we take in consideration 780Nm limiter and add 20% drivetrain loss it around 930Nm limit.