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Air suspension
- Thread starter P90D
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- Driving Dynamics Model X
Is that all?
What about adjusting the stiffness of the suspension?
At high speeds you want your suspension to be stiffer, so when you hit a small bump, especially in a curve, say when driving onto a bridge in a high-way junction, you want the car to settle down quickly. During normal driving a less stiff suspension is more comfortable.
For that the air-suspension in my Audi has a 'Dynamic' setting, as opposed to 'Comfort'. The other settings are 'Automatic' (for something in between) and 'Lift'. At high speeds (130 km/h or more for 30 seconds) the suspension lowers itself, and comes back up afterwards when you slow down, this is clearly visible with a complete stop right after the high-way exit. At purchase, there is an option to also get 'Sport', which I have not tried.
aesculus
Still Trying to Figure This All Out
I was kind of surprised that I could not find a ride stiffness setting either. The steering has various stiffnesses, why not the air suspension?
goneskiian
Active Member
Fanatic1 clearly missed which forum this was posted in and was referring to the Model S wheel sizes.
Fanatic1
Member
I was referring to Diavel's comments about his MS where he stated that he was eating through his MS tires which are 21s. I wanted to get a better understanding of why the 21s wear down so much faster since it seemed that it was suggested that it was the presence of air suspension and not the tire treads eat characteristics alone that were the main reason.
Yes, DuplexDiane, the MX comes standard with 20s. Diavel is getting an MX which is awesome! Just sat in one at the Tesla social in Burlingame last Sunday and enjoyed the hands on tour!
goneskiian
Active Member
Does ride stiffness not get more stiff when suspension is set to LOW? Wouldn't that mean the amount of travel in the suspension was less therefore stiffer? It may not work this way at all but just how I'm picturing it in my head. I've never had adjustable air suspension.
There's nothing in the manual that specifically states the ride comfort for the various heights. It's hard to tell suspension feel with a Seat-of-your-pants test but might feel a little difference between the normal and very high setting. The very high setting feels like you're floating over speed bumps a bit more and the normal settings feels a bit stiffer. They all feel pretty stiff but not sport-car jarringly stiff. Our Audi TT-RS has a "sport mode" that makes the magnetorheological fluid absorbers stiffer and you can really feel the jarring difference when it's on. The Model X has suspension has very little body roll (also due to the low center of gravity) and is more firm than my RAV4 sport Tokico blues. A long time ago, my mom had a 92 Ford Grand Marquis that rode on airbags and riding in that was like floating in a cloud (it made me car sick). The Model X suspension still lets you feel the road, but doesn't make your kidneys bleed.
aesculus
Still Trying to Figure This All Out
Blastphemy
Member
Right, the stiffness of the suspension is different from the height it can move. With increased stiffness in the suspension, any introduced vibration is dampened out quicker. The concept applies to many different systems, there is a pretty good explanation here (I think):
Vibration - Wikipedia, the free encyclopedia
A simple test of a car's suspension is to press down hard on the fender and then let go. With a stiff suspension the movement will stop as soon as the car comes back up, if there is something wrong with the dampening the movement will oscillate a bit up and down first. A non-stiff suspension will be somewhere in between.
The concept of stiffness applies also to non-adjustable suspensions, in the sense that two different cars each with a non-adjustable suspension, can have a difference in their stiffness. One can observe this by looking at different cars that drive with more or less the same speed over the same bump.
Diavel
Member
Model s 21" and 19".
Model x 22" and 20"
The 21's wear down much faster because it uses a low profile tire and also uses sport tires vs all season for 19's (sticker rubber on the 21's).
The air suspension lowers the vehicle. If you ever see an extremely lowered car, sometimes you will see that their tires are severely angled. That is because of negative camber and the lower the car goes, the greater the camber becomes.
Tesla also does this on purpose for better traction in the corners. All these are further exacerbated by the amount of weight our cars have vs a typica internal combustion vehicle.
Though I must point out that the air suspension is not the only reason for advanced treadwear. Tire type and size play a factor as well as how gradually you speed up vs just jamming the accelerator which causes more tire wear.
Diavel
Member
Apologies for the bad picture and lighting but you can see that the tire is not on the wheelwell straight. This is because of the camber.
Non performance drivers will definitely benefit from adjustable camber links installed. Tons of money saved of you have the 21s but you sacrifice some cornering abilities.
This forum used to have sellers for the links but there was no demand for it. I guess because people didn't want to lose their warranty rights as well as just rich people bought teslas. I suspect demand to rise as more used model s' and out of warranty cars become more available.
Non performance drivers will definitely benefit from adjustable camber links installed. Tons of money saved of you have the 21s but you sacrifice some cornering abilities.
This forum used to have sellers for the links but there was no demand for it. I guess because people didn't want to lose their warranty rights as well as just rich people bought teslas. I suspect demand to rise as more used model s' and out of warranty cars become more available.
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Diavel
Member
Definitely stiffer with suspension set to low. Best use of it for me is when I'm going pretty fast through a turn on standard setting, if there is a dip you feel the suspension unsettle leaving you with a scary feeling like you don't have much control and the car feels like it's list train for a brief moment. If it was put into low, you feel like the tires are more planted at all times. Less body roll too and the car feels like ago cart.
I am doubtful that car ownership is a qualification in this discussion, but in case others find it relevant, my family owns these Audis and I have driven more than 100 000 km in each:
A4 with a standard suspension
A6 with a lower and stiffer suspension
A8 with a variable air suspension.
While it makes sense to make a lower suspension stiffer, the stiffness is not actually caused by the suspension being lower. The extent to which the suspension is low (or high) is the amount of movement possible for the springs (air springs in the case of an air suspension like that of an Audi). The stiffness (or lack thereof) is controlled by the dampers, which are separate components. In Audi's adaptive air suspension, the dampers are controlled at the millisecond level, depending on road conditions, driving style, and the selected suspension mode.
A lower suspension (or more accurately, one that has a relatively limited movement) is natural to combine with a stiffer damper, to reduce the risk of the suspension becoming fully compressed.
So while there is a correlation between a suspension being low and a suspension being stiff, these two separate characteristics are determined by two different components.
So apart from people's inherently subjective driving experience with the X, I would be interested in hearing more about the stiffness of its variable air suspension.
engle
Member
There is none that I'm aware of after speed-reading the documentation when I received my X on 3/22. I think it would be a useful feature and should be suggested to Tesla.
For me personally, when I get to a parking lot where I've pre-set a "very high" setting, I know it because I can hear the suspension moving (kind of a mild creaking sound) and feel the vehicle rising. There's also the "suspension in motion" symbolic animated indicator if you switch to that screen. I've never been able to detect when it drops back down to normal, however. I set it to "very high" at all new parking lots so I don't have to worry about scraping the bottom fascia against the curb. Now I normally use the perpendicular parking space auto-park, which is one of my favorite secondary "auto" features, however, so it's no longer an issue for me.
Here is one in English:
Audi Technology Portal - adaptive air suspension
Thanks for the info on Bilstein.
Diavel
Member
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