suspension

[paulnl]

Dear all, does anybody have experience with air or hydraulic suspension??.
i would like to build a car with multiple options, hard for track and soft for long rides.
looking forward to your thoughts

[NAZ]

Air ride is not for performance cars, the spring rate is not consistent as temperature has a major influence.

Hydraulic is how shocks and struts work so what's your definition of a hydraulic suspension? I've seen hydraulic pre-load adjusters on track cars -- is this what you're referring to. These can adjust ride height and, therefore, instant center. I've seen them on street / track day cars where they were used to quickly adjust ride height for street duty and track use but remember, this affects suspension geometry and handling. These simply mount between the spring and spring base on a coilover shock. But not sure you'd be happy with this set-up for adjusting your suspension "hard for track and soft for long rides" as cranking in on the springs does not change the spring rate which is really what your asking for. Soft ride = lower spring rate. Jacking ride height changes handling and is not the way to change how soft or hard your car rides.

[edwardb]

Not sure which Factory Five model you're interested in. But have you actually ridden in whatever it is you're considering? First, they're by definition performance cars with race style limited movement suspensions. So not sure where either air or hydraulic would fit into that. Second, you might be surprised how compliant they are. Everyone who rides in my builds is surprised how they ride. Don't float over bumps like your father's Oldsmobile (not that you would want that) but also don't jar your teeth loose some like some seem to expect. Actually quite pleasant. Given the typical somewhat cramped space, often open top, weather, etc. these aren't typically long distance drivers. On the typical cruises we do (up to a few hundred miles) ride quality is not high on the list of distractions. Depending on how you plan to use the car, there are also options for spring weights and shocks that can make the ride a little more hospitable. Finally, IRS, if available in whatever you're looking at, will almost always give the most comfortable and compliant ride.

[Logan]

I just posted this in your other thread (with the exact same title). Copy and pasting here:

My good friend and I both drive S550 Mustangs daily as well as autocross regionally. I’m on coil spring and dampers, and he has installed a complete Air Lift suspension in his. I can tell you it’s a pretty slick system overall, he can raise or lower his car something like 6+ inches. From laying the frame on the ground tires and wheels tucked inside the fenders all the way to 4x4 mode sitting so high you can stick your fist between the top of the tire and the bottom of the fender. Very handy actually...on steep approaches he can lift the front or rear and once over the obstacle lower back down.

Now...as far as the track performance, this is where it gets fuzzy. There’s no such thing as “Spring Rate” for an airbag. So you can’t compare it to any other regular suspension, including mine. I know what my rates are, and can be pretty statistical in calculating swaybar rates and damper curves, but he cannot. The stiffness of the bag is more about pressure and volume. If you want a soft ride on airbags, you need to have less air pressure in the bag, but not less volume (or it would be bottoming out everywhere). We have still not achieved a balance in his car that gets a softer ride than my traditional springs give. Maybe we’re not doing something right, but it’s going on 2-3 seasons now with plenty of tinkering and it’s still about the same as the day they were installed. During autocross, he lifts the car nearly to the top to clear his big wheels and tires, but this makes the bags pretty firm and plus his center of gravity is now way higher than a stock Mustang.

Takeaway here: Airbag suspension is a nice setup for street cars who want the WOW factor of dropping it low, or the convenience of raising the car on command. For pure track performance, stick with traditional springs and dampers.

Also,

NAZ is referring to something like the JRi Hydraulic Ride Height System. Fancy and super cool tech. 1-3” of ride height adjustment on a coilover, without affecting spring rate or damper performance. It does affect geometry though. At roughly $5-6k, I passed this time around.

Also agree with EdwardB, you’re going to have some packaging concerns when trying to fit any of these options to a FFR. Go find someone and get a ride in their car. You can have a nice balance of street and track performance with decent ride quality. It’s all about the spring rates and swaybar rates.