Got a new set of Yokohama AD08Rs, got around 25k kms out of the rears. Fronts had some life left, keeping them for a skid pan day
The M3 LSD is going well, initially the diff made a bit of a groaning sound when doing full lock turns quickly, but now the diff has quietened down after about 800kms. At very low speeds on full lock you do hear the inside tyre shuffling a bit as well. Will be changing the fluid out after the 1k-2k kms mark.
The M3 GKN viscolok unit takes some time to get used to, it doesn't react immediately and relies on some wheelspin to generate some lock. I would honestly prefer a plate diff. Having said that, its a massive improvment and I get a lot less DSC intervention under power out of corners. Before you would have to just wait until the car is straight before touching the throttle but you can be quite early on the power now. The M3 diff does not seem to cause any power understeer, I have driven a Quaife unit which didn't really want to turn in under power.
I initially drove the car with almost bald rear tyres with the LSD, you can really do slides at much higher speeds than with the ediff, you will have to be more careful obviously. Before the ediff was pretty ineffective with grippy tyres in the dry, only with bald tyres in the wet it seemed to be effective in locking up the rear axle.
Now with the new AD08R tyres and LSD I sometimes get the inside wheel kicking up briefly before locking up, otherwise its usually just a slight intervention of DSC while the car is being propelled out of a corner quickly. I would say the best description is that the GKN unit feels like the stock ediff but has the power to lock up the axle at high speeds and on dry tarmac. You can definitely feel that it is a reactive system and a torsen diff is a lot smoother in how it biases the torque.
The GKN unit is capable of locking very hard, (up to 100% according to the specs), which you can definitely feel. Sometimes it is a bit of a disadvantage, as it can lock up a too hard and cause a bit of oversteer on corner exit. Currently my car is biased towards understeer so its not a big deal. Sounds like I am complaining but overall the pros outweight the cons. The LSD definitely gives the car a lot more character actually.
The GKN diff I think must be one of the main reasons why the 1M feels a bit twitchy, I think with a plate diff or torsen diff the character of the car would be changed again significantly under performance driving.
My only regret is not getting this LSD in sooner, it transforms the car. I would highly recommend getting an LSD into the car as soon as possible.
Heres an interesting youtube video comparing open, clutch and M variable (GKN viscolok) lsds: