But did Subaru really increase rear roll stiffness relative to the front?
They fitted a 1 mm thicker rear bar but took 10-15% out of the spring rate, according to various journalists. I've not seen any confirmed numbers anywhere as yet. Front spring rates went up. Nobody seems to know by how much.
Our Australian friends were told 10% stiffer front and 15% softer rear forints:
https://www.motormag.com.au/reviews/...yota-86-review
The comments about the LSD (still Torsen) are interesting. What did Subaru (Toyota actually as this is a Lexus unit) do there I wonder? Just btw, a Torsen LSD cannot chatter, there's nothing inside that can do that. The tires can and do alternately grip and slip across the axle under high differential loading caused by hard launches with lots of grip or by hard slow tight cornering in first gear.
Objectively, reducing rear spring rates and increasing front spring rates should increase the tendency to understeer. It should also make it easier to get power down to the road, an Achilles heel for this car from 2013 and not addressed until now. I wonder if this makes the LSD feel less active because it is due to more chassis grip at the rear axle, not because of any internal changes.