Ground clearance! How low is too low?

What is this "Ground Clearance" Problem you speak of? New suspension parts will give me an additional 2 inches. Enough?

In reply to Ovid_and_Flem :

Nope, not enough.  I am at 12" clearance and the underside looks like this:

Humorously, you might be too low if...

In reply to Hal :

Beautiful fabrication. But what is it?

I've been building the Rice Rod's frame sitting on the vertical side of 2x4's, so I sure hope 3.5" is enough. I put a beefy cross-member under the oil pan, so it will hit that first.

In reply to maschinenbau :

Presuming it’s not your main car, or even your backup car, you’ll be fine...as long as you plot your course to avoid tall speed bumps. 

In reply to Ovid_and_Flem :

Iirc it's a lifted outback

As Kieth said spring rate is a factor but so is wheelbase and overhang.  You can get away with a lower S2000 than a '90s GM wagon.  All that being said when you get below 3.5" you're going to be occasionally dragging something on something on a street car.

I also really don't like it when the oil pan is the lowest part of the car.  I try and avoid that no matter what the ride hight is.

It depends on what you're trying to clear as well. If your oil pan is between the front wheels, then you're safe from speed bumps but you might take it out on a rock or a crowned road. That's where wheelbase comes into play. If you're dealing with sloped driveways, that's overhang and again anything between the wheels is safe. Making sure your front air dam is one that can flex instead of shatter comes in really handy.

I have found that 4" is the minimum if you don't want to pre-run roads with another car.