Driving low on bags = Soft ride?

[wagonist]

I'm a complete newb when it comes to airbags, so please excuse my lack of knowledge.

For the last 10 years I've only owned coilovers, several variants, cup-kits, and various springs with koni adjustable shocks. With all the options mentioned above, the logic was that the lower you went the stiffer the ride got because the shock was getting maxed out and the spring retained the same spring rate at no matter what height. That was great because when your oil pan is 1" off the ground you really dont wan't any suspension movement.

Now, I don't know the precise physics when it comes to bags, but logic would say that the lower the bag pressure, the lower the car, the softer the bag. Right? So basically you got a spring that looses its spring rate the lower you go? Thats basically the opposite of what I want. At this point I'm guessing that all those super low cars I see here are actually jacked up high when they drive around in real life.

If I'm wrong please correct me cuz right now I feel like a kid that just found out there's no Santa

Are hydraulics a better option for driving low, or am I pretty much stuck with coil springs if I want to drive low daily?

[Han]

Now, I don't know the precise physics when it comes to bags, but logic would say that the lower the bag pressure, the lower the car, the softer the bag. Right? So basically you got a spring that looses its spring rate the lower you go? Thats basically the opposite of what I want. At this point I'm guessing that all those super low cars I see here are actually jacked up high when they drive around in real life.

?

You are right in theory, but there are a few different things that equate to the ride in real life such as: dampening of struts, how much actual PSI is in the bag, FBSS or just FB, etc.

Also, if you do bags over coils, you can adjust how low/high the bag is on the strut and that also equates to a different ride feeling. I drive with 80psi all the way around, but that's only about less than an inch higher than laid out. Yes, I still drive low on air.

[aar0n.]

I drive low in my bagged car and it rides like a cupkit. If I wanted a stiffer ride (which I absolutely do not), I could just spin my bags up on the coilover body and drive at a higher PSI while keeping the same height (pretty much what Calvin just said)

[Rally]

It really depends on the setup. Things like the stack height of your upper mount, the location of the lower perch, the volume of the bag, the height of the bag, etc.

For the most part, on your average single bellow bags 30-40 psi is a nice comfortable pressure to run. Bags reach full lift around 90-110 psi, so you can imagine that filling the bag to 30-40 only lifts in slightly

I run my fronts in the 30's and that's still nice and low. It tucks tire and still scrapes occasionally. It's not super bone-jarring stiff, but it's definitely not too soft to cruise around on. Things start getting too soft when the pressures get into the low 20's.

Most people still drive low on bags. As long as you set it up for that, you'll be able to cruise low no problem.

[Doc]

yes every setup is different

i have Yellow adjustable Koni struts with my bag setup so i decide what i want in the firmness department.

i run between 35-40 PSI depending on road conditions
bags full are about 60 PSI
and when dumped i reach full low at about 12 PSI

this is with 22" wheels that need lots of space to turn to prevent substantial rubbing

[Nighttrain1974]

In theory you're correct, in practice it doesn't go that way.

You have to remember the bags aren't static like springs, they actually move when you force air in or out. This means that even when they're quite low, you can still drive without bottoming out.

As you put more air in the car raises so you're not stiffening the spring as such, you're increasing the volume of air in there to adjust your ride height.
The psi gauges are misleading on air systems, really they should be volume gauges but most people feel happier with psi as they understand it.

The "feel" of air depends more on your dampers and top mounts, stiffen up those shocks and you can rail as hard as coilovers. Same with top mounts, the harder or softer they are will affect the ride greatly.

If the bag was a static shape (think football) then the higher and lower the psi would affect how hard or soft the ball is.

I hope that made sense. When you raise or lower with air you're not really making the spring harder, just increasing it's volume. If you actually feel a bag when it's under load on the car there's hardly any difference between when you raise it one inch to raising it three inch. It's only when the bag itself can't expand anymore that the ride will get harder the more air you push in.

In other words the ride should feel the same whether you're scraping the floor or sky high.

Hydraulics work the same way. More juice, more lift.