installing LSD on AWD Car

Late reply as I missed this thread. Glad to be able to add some experience on the forum for a change, so here is my 2c.

I have a helical rear LSD (Torsen) fitted on my car (old school 1990 Audi Coupe quattro). I also have a 40/60 F/R static bias Torsen centre diff from an RS4. The front diff is open. Both these mods have transformed how the car drives. It is very neutrally balanced on the power (rather than understeering as before) and driven correctly, tends to loose traction at both axles at the same time, a 4 wheel drift which very controllable on the throttle. Of course you can provoke either U/S or O/S condition if you are lairy. For reference a good mate of mine has 3x Gripper plated LSDs in his quattro band he said it was not pleasant to drive on the road - track was good but if i remember right he had to play around a lot with the ramp angles on the front as it was causing some braking issues. For this reason I've steering clear of fitting an LSD up front, however I am still keen to try it at some point, using a helical diff such as a Wavetrac or Torsen rather than a conventional plated LSD.

I did a full drivetrain swap on my WRX with an STI (my wrx had open diff;s) now It is running a front Quafe LSD.. STI center diff (not sure what that one is, Torsen I think?) and a cusco 1.5 plated diff in the rear. I'm also controlling the center diff via the MapDCCD system. So far it have been a great upgrade for the track. I have had to re-learn my cornering as I get so much more traction it is easy to over steer. just make sure your gear ratios are compatible or you will have issues.

In theory, certainly and, as some have commented, it can transform some vehicles.

However, it will also depend on what the car is being used for for the 'best' type, which axle(s) and what the centre diff (if not locked) is and, of course, what is available for the vehicle.

Some modern vehicles use braking on selected wheels to help control the vehicle in extreme circumstances and/or torque vectoring - I wouldn't expect a slip limiting differential to cause problems with the first but perhaps the latter - if it is even possible to fit one.

Definitely get as much feedback from sites specialising in the vehicle to see what is recommended, specific problems, etc - could save a lot of money. I would also suggest reviewing your suspension/tyre package as that may be a better option, at least initially.