981 S Manual LSD/PTV Retrofit

[HosonAndersson]

Hello,

Is it somebody who knows f it´s possible to retrofit a LSD to a 981 3,4 manual? I´m planning to build a sort of "Clubsport" 981 CS and have found a used object with perfect options, X73, Carbon bucket seats, Sports exhaust and Sport chrono.. But no PTV unfortunately.

[TDT]

HosonAndersson said:

Hello,

Is it somebody who knows f it´s possible to retrofit a LSD to a 981 3,4 manual? I´m planning to build a sort of "Clubsport" 981 CS and have found a used object with perfect options, X73, Carbon bucket seats, Sports exhaust and Sport chrono.. But no PTV unfortunately.

So, PTV is made up of two components

For corner entry - Brake Steer/Pinching of the inside rear wheel by the braking system - in order help the car pivot in and turn more quickly.
For corner exit - Mechanical LSD - to ensure that both wheels are driven for optimal forward thrust out of the corner.

If your car doesn't have PTV - then you can retrofit the LSD - no issue, however you cannot do any to add the Brake Steer/Pinching for corner entry.
This is a feature of the PSM programme.

Various opinions on whether or not the Brake Steer/Pinching is valuable - I specified my car with PTV - primarily for the LSD.

The Factory Cayman LSD is 22/27 split - this the same on the Base, S, GTS and GT4.

[VladD]

If the LSD was fitted, then would the PTV part be just a software change or are there additional sensors etc., that are required for PTV over and above what PSM has?

[HosonAndersson]

I have E-mailed Quaife but they don´t know if the same diff as to the 987.. "We do not have a listing for the 981 Cayman S, however, the QDF12Q may fit as Porsche do not tend to change their diffs that frequently.
I have attached the dimensional drawing for the QDF12Q diff. Please use this to confirm whether it is the same as the standard 981 diff."

Guard Transmission is also offering two different diffs, the classic "LSD" and "Torque Biasing Differentials".. Which is the best for say 50% road and the rest autocross and track use?

[TDT]

VladD said:

If the LSD was fitted, then would the PTV part be just a software change or are there additional sensors etc., that are required for PTV over and above what PSM has?

No idea to be honest. But when you spec PTV from the factory, you also get slightly revised ARB - on the rear iirc.
I don't know if a dealer would so a software flash or change to enable PTV functionality.

Thing to remember is that PTV does actually increase brake wear on the rear.
If you have an LSD or more aggressive LSD that the factory this will mean more load goes to the LSD and there will be less demand on the braking system.
The factory Cayman LSD is generally regarded as pretty mild.

[TDT]

HosonAndersson said:

I have E-mailed Quaife but they don´t know if the same diff as to the 987.. "We do not have a listing for the 981 Cayman S, however, the QDF12Q may fit as Porsche do not tend to change their diffs that frequently.
I have attached the dimensional drawing for the QDF12Q diff. Please use this to confirm whether it is the same as the standard 981 diff."

Guard Transmission is also offering two different diffs, the classic "LSD" and "Torque Biasing Differentials".. Which is the best for say 50% road and the rest autocross and track use?

From what I've seen the 981 LSD is the essentially as the 987 one as you said.
Guard Transmission are highly regarded - I believe the TBD is what is required if you don't have an LSD already.

[scz4]

Slightly related, wonder if anyone offers a shorter final drive ratio yet? Would make sense to fit this if in there messing around with the internals. Although not quite a important with PDK.

[HosonAndersson]

So I recived a answer grom Guard Transmission regarding their TBD for the 981 CS. "Thank you for your interest in our products. Because of the new oil pump inside the gearbox we have had to redesign our Cayman LSD. We are close to releasing it, but it will still be about a month." I think this will become a nice solution for those who don´t have PTV on their cars.