Air suspension height vs stiffness

[TomekGnomek]

I've noticed (something obvious) that driving with the lowest possible height setting changes this car to something very close to a sport sedan. It's really great and this is my go to mode for city driving.

I've been playing with different settings and I wonder... do you have an impression the suspension is more firm/stiff when in low mode and more comfortable when in normal or terrain mode?

The stiffness should be regulated by a separate normal/sport/sport plus mode but the difference in handling between height settings makes me wonder if it does more than just lowering and lifting the car. The manual is vague on this subject.

 

[M324]

tbh I don't recognize any difference in stiffness if I just put the height to the lowest option. That's why I am also driving in lowest height but with normal stiffness.

 

[Fleming23]

On 22" Spyder wheels, it is only marginally more bumpy in "low" vs "lowered." I have been playing with mine and can't determine if it is a placebo effect when running the lowest setting vs lowered or not. Most of the time I stay in lowered vs low.

I do want to put my car on my alignment rack and determine what the suspension is doing in the 3 settings for tire wear purposes. I fear running in low could be changing toe and or camber to the point we see premature tire wear.

 

[TaycanEagle]

My daily driving preference is normal chassis and lowered height. It gives me the best balance of comfort and performance for daily driving, especially with the horrible Dallas roads I drive. I also used the same combo in my Taycan 4s.

 

[krissrock]

I've noticed (something obvious) that driving with the lowest possible height setting changes this car to something very close to a sport sedan. It's really great and this is my go to mode for city driving.

I've been playing with different settings and I wonder... do you have an impression the suspension is more firm/stiff when in low mode and more comfortable when in normal or terrain mode?

The stiffness should be regulated by a separate normal/sport/sport plus mode but the difference in handling between height settings makes me wonder if it does more than just lowering and lifting the car. The manual is vague on this subject.

remember you can toggle the height and the dampers separately. Dampening really makes a big difference. So you may want to play around with the shock settings independently of the ride height...
but i don't know what shock settings are paired with the ride height... It's possibly you can have the car "low" and the shocks still be in normal/soft as opposed to "stiff"

 

[ColdCase]

Yeah, two thing at play.

The car height is raised by pumping air into the air springs which is the same as stiffer springs, lower and its softer springs.

The "stiffness" shock is also adjustable.

A low height with stiff shock may ride the same as a normal height combined with a softer shock setting.

 

[Awaz]

Dampening really makes a big difference. So you may want to play around with the shock settings independently of the ride height...

Is it possible to soften the shock settings in normal? If so, kindly let us know the steps to do so.

 

[krissrock]

Is it possible to soften the shock settings in normal? If so, kindly let us know the steps to do so.

you see how there's "level" and "chassis"
Level refers to the ride height, and Chassis refers to the dampers/shocks

 

[dgkhn]

Yeah, two thing at play.

The car height is raised by pumping air into the air springs which is the same as stiffer springs, lower and its softer springs.

The "stiffness" shock is also adjustable.

A low height with stiff shock may ride the same as a normal height combined with a softer shock setting.

On the issue of greater ride height meaning stiffer springs: I am not so sure about that. (I am not an engineer and this thinking may be faulty, but, think about what's happening.) The air pressure in the springs is adjusting the ride height. More air, more height. But. statically, the pressure is equalized. Meaning: as you pump air into the spring chamber, you're raising the car--the volume in the chamber is increasing because there's more air in it. But, the pressure inside the chamber should remain the same assuming you haven't reached some mechanical limit; it's simply sufficient to support the car's weight either way.

So I'm pretty sure, the stiffness is primarily due to PASM (i.e. the shocks). Greater ride height gives you more room to absorb bumps, and more rebound (and presumably the potential for more roll.) Also, in one sense the springs are softer with more air, because any given compression of the spring is less proportionately (i.e., an inch of compression is a smaller fraction of the total available compression, and proportionately the air in the chamber is compressed less by the same momentary impact). So, I would assume that lowering the car contributes to flatter handling, and this is why in sport mode (I don't have Sport plus), the shocks are stiffened AND the ride height is decreased.

On my previous Macan GTS with air springs, I felt that lowering the ride height in itself made the ride feel stiffer, not less stiff (that car had separate buttons for ride height and PASM, making it easy to switch among the various combinations...those were the days, but I digress). I really have not noticed that on the Macan 4, although it may be due to the fact that most of the roads I've been driving on lately are better (having moved from Long Island to New Hampshire) (i.e. it's less noticeable on a smooth road surface). I have not driven in the fully lowered position.

 

[krissrock]

I have feeling only the ride height is air controlled. the shocks are most likely electrically managed oil.

 

[ColdCase]

On the issue of greater ride height meaning stiffer springs: I am not so sure about that. (I am not an engineer and this thinking may be faulty, but, think about what's happening.) The air pressure in the springs is adjusting the ride height. More air, more height. But. statically, the pressure is equalized. Meaning: as you pump air into the spring chamber, you're raising the car--the volume in the chamber is increasing because there's more air in it. But, the pressure inside the chamber should remain the same assuming you haven't reached some mechanical limit; it's simply sufficient to support the car's weight either way.

At the simplest level think of tires. The air in the tires is holding up the car. A tire with no air/pressure is flat. Forcing air into the tire with relative pressure raises the wheel off the ground. Releasing the pressure/air flattens the tire and lowers it. A tire with little air volume/pressure is softer than one with more air/higher pressure.

Air suspension raises a vehicle by inflating the air bags. It probably does not make that much stiffness difference between normal and low levels, however. You would see a much more dramatic difference in off road vehicles that can adjust to provide 4-5 inches more ground clearance than normal.

I do think the differences in Macan "ride" is more influenced by shock dynamics and adjustments. The lower ride height improves handling by lowering the center of gravity, lower height also improves aero dynamics. Lower ride height also reduces suspension travel, more chance to hit bump stops and Porsche may be tuning to ease that pain that results in more overall stiffness. Higher height reduces rebound.

 

[RichardT808]

I have had my Macan 4 for a bout a month. Where we live the rode is extremely bumpy, windy and full of potholes. Because of the road conditions, up to our house I opted for the “standard” 20’ wheel/tire setup. What I’m trying to figure out is why the Turbo Macan and another Macan 4 with the 21” wheels were dramatically smoother on the same road as my Macan 4 with the 20” wheels. Tires” the nasty rock hard Pirrellis on th3e 20” vs the Michelins on the 21”? What I have noticed is in ”Sport” and ‘Sport Plus” the ride seems to be smoother - which is counter intuitive. My prior Macan GTS had the air suspension was was definitely smoother. Any feedback would be great!

 

[dgkhn]

At the simplest level think of tires. The air in the tires is holding up the car. A tire with no air/pressure is flat. Forcing air into the tire with relative pressure raises the wheel off the ground. Releasing the pressure/air flattens the tire and lowers it. A tire with little air volume/pressure is softer than one with more air/higher pressure.

Below is how I think about this; I am not saying it because I "know" it as a fact, and maybe I'm wrong, so if someone wants to tell me what I'm missing, please do.

The difference between tires and air suspension is the relationship among the amount of air, pressure and volume. (Volume is the physical cubic volume of the inside of the container, NOT the amount of air). Unlike tires, the air springs are designed to increase in volume as more air is added (hence the change in ride height.) Within the limits of mechanical expansion/compression, the static internal volume of the spring is more or less proportional to the amount of air in the spring. PV=nRT, where n is the number of moles of gas (so, the amount of air in other words.) R is a constant, and T is temperature so let's ignore them for this analysis. So Pressure is proportional to amount of air divided by volume. If you increase the amount of air, and the volume goes up proportionally, the pressure stays the same. This is just ideally; I assume in reality the volume may not go up quite proportionally, but I think it should be close.

How is that different from a tire? True, as you start to add air to a flat tire, its volume initially increases. However, once the tire is fully inflated, adding more air marginally changes the volume, if at all, so the pressure increases (as opposed to a balloon, for example, which keeps increasing in volume as you add air). Therefore the tire pressure increases. Think of it this way: the tire is pressurized even when off the car (when not supporting the car's weight). This is different from the air spring, where within the design limits, adding more air increases the volume.

What happens when you hit a bump? In the case of the tire, the higher the pressure, the more resistance there is to deflecting (temporarily reducing the volume), so the harder the ride. In the case of the spring, the static pressure is fairly constant, but there is more "travel" when the suspension is raised to absorb the bump (i.e. a 1-inch deflection is proportionally more on the "short" spring vs the "long" spring, so in principal the longer the spring, the softer the ride (this is before you start talking about shock settings of course--the shocks are also resisting the "bump," controlling the rate of compression, and also slowing the rebound.)

My thoughts, anyway.

 

[rmwrip]

I would also like to know the ride difference between tires. From what I gather so far it may be worth making sure (even if I need to swap) I have Michelin or Goodyear. If I do need to swap what would the best choice be? I’ll have 21 inch wheels on a Turbo.

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