I remember the first time I drove a BRZ a little before it hit the streets and thinking....damn....Subaru/Toyota got serious.
Anyway, this is a list of things that I see owners doing to their 86's...often with good intentions and parts bought hoping to improve things, but they end up chasing more parts to get things right. All of these on their own are detrimental, but can sometimes be "worked around" to some extent. Unfortunately many cars check off multiple boxes and sometimes all of them...resulting in a car that is a big step back from the factory.
I'll skip "stanced" cars (slammed, stretched tires, massive camber)...I don't think anyone does that expecting not to sacrifice function for what they think looks good. Different strokes.
These are some of the common things I see:
1. Staggered wheels/tires
It's a good look and definitely makes your car look like it has a lot of power. Unfortunately our cars don't have a lot of power.
It's also a great way to build in some extra understeer that's difficult to tune out. Staggered wheels are common on cars with a lot of power but are not necessary MOST the time here.
This one CAN be worked around but there's just no need to complicate things.
2. Big ass heavy wheels
Even if you got a great deal on a buddy's 18x9.5 wheels, it may not be a great idea to use 27 lb steamrollers at each corner. Most of us don't need that much tire either. Keep it light and it'll feel like your dampers are much more capable. You'll stop and go faster too.
3. Big drop on lowering springs
If it looks a racecar then it must handle like one, right? Unfortunately, it doesn't exactly work like that. A little drop can improve things with proper spring rates, but past an inch or more and you start making big compromises and riding the bumpstops before you even hit a bump. It's a sure way to downgrade your handling. Aftermarket shocks may help in some ways, but don't solve the travel problem.
4. Big drop on coilovers
With some coilovers you don't need to worry about bump travel as much, but geometry is still a concern when lowering 2 inches. A big change in roll center height and changes in the dynamic alignment can be felt from the driver's seat...and it feels sloppy.
I know what you're thinking. There are a ton of cars on here that hit the track and handle well with a lowered ride height. If you must have that really low center of gravity than you must use very firm spring rates (and then quality dampers to match) or use geometry correction parts. That's what the fast guys and girls at the track are doing....not slamming their crappy coilovers to the ground and expecting all to be well.
5. Poor or mismatched dampers
Whether it's running very stiff springs on the stock shocks (or riding the firm bumpstops), or turning your adjustable dampers up to full stiff, damping that's not matched to the springs won't feel good. Underdamped will feel bouncy, floaty, and generally crappy in transitions. Overdamped will feel harsh, crashy, and might hurt your back. None of this is good for ride quality or handling.
Sometimes an adjustable won't have a "good" setting because the quality of the valving is just plain bad. This is more noticeable with firmer spring rates.
6. Alignment
Anything less than -1 degrees camber up front is a recipe for understeer. I still see people trying to get their camber "back to 0" after lowering. Don't do this! Tire wear isn't really a concern until you get to -2, so don't be shy...add a little camber and enjoy. Most enthusiasts will get BETTER and more even tire wear anyway. Toe is the tire killer.
7. Tire choice
Really stiff springs with all season or OEM tires can reduce grip as you'll be quickly/easily overloading the tire. Match your spring rates to your tire choice.
Running sticky tires on soft OEM springs is a problem too, but you will still gain grip from the tire. It'll just feel sloppy and move around a lot.
Thanks to Racecomp Engineering