A) marketing people don't really write owners manuals. B) it works like a limited slip diff, but you say it can't be called one.
I call BS.
Here we go again...
The term LSD (limited slip differential) has been around for decades (circa 1950's)...& way before any fancy clutch pack electrohydraulic stuff..
Therefore the definition has actually been defined for decades in mechanical terminology & dictionaries...
& is thus usually described as a device having one input shaft & two output shafts with the "limited slip" part in-between...
Why the GTI PP FXD is not an LSD:-
1. Only one input shaft & one output shaft
2. Is fitted AFTER the existing "open differential", therefore if it was an LSD you would not have the existing open diff, as an LSD replaces the open diff.
3. Is electrically based, & heavily reliant on the ABS unit & sensors, ESC units & sensors. Get a failure in the electronics board or one of these units & bye bye FXD! An LSD does not rely on electronics or other systems, no fuse to be pulled on it.
4. The mechanical documentation I referred to previously DOES NOT call it an LSD, they call it by its correct mechanical terminology "Front diff lock, Electrohydraulic front diff lock".
Why you might class it as an LSD & therefore what other systems you must state are LSD also
1. marketing to basically sell anything which can stop one wheel spinning more than the other on the same axle...
2. So that includes EDL (electronic diff lock) & the aforementioned XDS, as that is what these systems do.
3. Wiki lists every type under "limited slip differential"..including the brake based systems mentioned above.
https://en.wikipedia.org/wiki/Limited-slip_differential
Basically in simple terms the FXD is fitted to the driveshaft on the passenger side (USA) after the existing diff & all it does is "lock up" to varying degrees the driveshaft on that side causing the existing open diff between the FXD unit & the gearbox to "lock up". This is why it is correctly called a "front diff lock" in the mechanical papers I mentioned...& NOT an LSD which operates in a different way as it is a self contained unit fitting between the gearbox & the two driveshafts....& contains a "limited slip device"
If you want to carry on stating you have an LSD in your GTI PP, then so do I with my XDS system..in fact my 14yr old VAG car (built 2000) had an LSD then as it had EDL which comes under the brake based LSD systems on wiki...