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Question for all the future GR86 owners here:

Do you hope the GR86 is just as tail happy as the 86/FR-S? Or do you want it to be more planed?

Frankly I love how much the back end moves around on you, but only when you want it to. It makes you feel like a pro.
 

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Well remember Scott Speed driving it was getting the BRZ tail happy but at higher speeds. The difference this time around is the new car has the power to push the tail out where as the old car needed those Michelin Primacy tires with little to no grip to get the tail moving.
 

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Short answer to that is no. I will track the car and take it for spirited drives on mountain roads - random oversteer is not your friend in those situations. The tail happy nature of the early 86 was about having more roll stiffness in the rear end of the car - rear spring rates were much higher than the front. That's not a setup that leads to a quick and predictable car at speeds much faster than an autocross.
 

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Are you saying that non performance tires have no determination on cornering grip? I am confused.
Grip, yes. Understeer vs oversteer, no.

The original FT86 twins had those same slick tires front and rear, so the tires weren't the reason the back end came around. Tail-happy is about several things - rear wheel drive (check), lots of torque/power (no check), weight distribution (no check), more tire grip in the front (no check), or relative roll stiffness between the front and rear ends (big check for the FR-S, smaller check for the BRZ). As a comp, the Miata has very similar power, similar weight distribution and equal-size front/rear tires, but it doesn't have that tail-happy characteristic.

For the example of how much roll stiffness matters, look at the first gen (2000-2003) vs. second gen (2004+) Honda S2000. First gen had a reputation for snap oversteer (earned - I saw a guy lose one so badly at an autocross he hit a light post the organizers thought was unreachable). The second gen could be provoked into oversteer but was largely neutral in its behavior. Both gens had a 48/52 front/rear weight distribution (FT86 is more like 52/48). Both had the same power, but gen 2 had more torque. Both had grippy tires - there was a little shift towards wider tires in the back for gen 2 but not enough to make a real change. But for the second generation, Honda took a lot of roll stiffness out of the rear of the car - a slightly smaller sway bar, but especially softer springs. They also stiffened the front springs a little. You could still get the car to rotate, but it didn't have the same tendency to swap ends unpredictably.

For reference, see: https://ast-suspension.com/docs/tech-talk/Setup-Tips-Anti-Roll-Bar.pdf
 
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