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Personal comparison between 85 Air Suspension and 85 Coil Suspension

Discussion in 'Model S' started by rogbmw, Jul 14, 2014.

  1. rogbmw

    rogbmw Member

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    I own a Standard 85 with air suspension and while it was in for service I had the opportunity to drive an 85 with the coil suspension and form a personal comparison of the two. The Coil suspension was tight and controlled, but I though it was just a little more "jiggley" than the smoothness of the air suspension. Having said that, I could happily live with a coil suspension car. The Coil suspenson car had the 19 inch wheels, and my car has the 21 inch wheels with the air suspension and I thought that due to my 21s it would be just the opposite. This comparison was done on the same roads I drive every day.
     
  2. green1

    green1 Active Member

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    No offence, but you didn't do any comparison between different suspensions.

    If you're comparing the suspensions you'd have to have the same type of wheels and tires, otherwise you have no way of knowing how much was suspension and how much was wheels, and how much was tires.
     
  3. rogbmw

    rogbmw Member

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    I understand exactly what you are saying - but it was just a butt-in-the-seat comparison over the same roads I drive every day of the two cars. As a driving instructor at BMW driving and safety schools, I understand the difference between different types of suspensions, wheels, tires, tire aspect, etc. It was just an observation. But - I thought a suspension with a wider sidewall profile and coils would feel different (maybe smoother) than one with air suspension and a shorter profile. What I was surprised to observe is that - at least between my car with 21 inch wheels, Michelin tires, and air suspension, and a similar car (both are S85 cars, no P or P+ 85 cars) with coil suspension and 19 inch wheels and Michelin tires - that the air suspension car on lower profile tires was somewhat smoother driving in similar conditions.
     
  4. Zarwin

    Zarwin Member

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    Owning a coil and driving a loaner for a day with air suspension, my 2 cent opinion is that air is smoother at slow speeds on rough roads. To me both feel nearly identical at 70mph on a decent road surface, though this was just a day of driving...
     
  5. Zextraterrestrial

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    I have had a loaner with coils and 21"s vs my car with 21"s and air - both were P cars. My car has the original bushings. I thought the coils felt floaty compared to the air. Mostly over bumps where the car bounces a bit, the coil suspension seemed to have an extra bounce to it where the air settles after the first bump.

    19"s vs 21"s make a huge difference in steering feel and ride smoothness so it would be very hard to compare the two on different suspension
     
  6. Gizmotoy

    Gizmotoy Active Member

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    #6 Gizmotoy, Jul 15, 2014
    Last edited: Jul 15, 2014
    I think maybe we talked about this before, but that's actually the exact opposite of the usual experience between air/coil. Air suspensions in general smooth bumps, resulting in a sensation usually described as "floating." A coil suspension absorbs the impact and immediately hits back, which is usually described as being "bumpy" or "punishing" depending on the spring rate and damper settings. However, if you were in a car with coils and found it to be "bouncy," that is usually a clear indicator that the dampers or suspension have failed. Certainly it's not something you should feel in a new Model S.

    Edit: Could just be a terminology thing. Though if it felt like the coil car had an extra bounce, there was almost certainly an issue with its dampers.

    As an aside, anyone curious is welcome to ride-along at ReFuel this weekend. I can't tell you I'll be anywhere near the fastest out there, but it might give a good insight into the differences. I wasn't able to swap out my crappy MXM4s for summers, though, so the test will be somewhat tainted.
     
  7. rogbmw

    rogbmw Member

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    That is what I would have guessed too, and to somewhat what I observed. But my seat-of-the-pants feeling was that the air suspension car with 21's had less "jiggliness" than the coil cars with the more forgiving sidewalls of the 19s (and my background is coming out of BMW M cars). But...I would take either over any other alternative!
     
  8. lolachampcar

    lolachampcar Active Member

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  9. yobigd20

    yobigd20 Well-Known Member

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    I have air suspension with 19" Michelin pilot sport A/S 3 and I just had a loaner car for the last 24 hours that had coil suspension and 19" Michelin primacy. A huge difference between the two. The coil suspension was rougher. The air suspension eats the bumps making it a much smoother ride. The pilot sports also have an incredibly better grip and overall ride quality and noise reduction compared to the primacies.
     
  10. green1

    green1 Active Member

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    Again, you can't say that the pilot sports have better ride quality when you compared them on a different suspension. It works both ways. You can never compare the suspension, OR the tires for ride quality if you've changed both at the same time. (The grip and noise comparisons are probably valid though)
     
  11. tga

    tga Active Member

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    I've given up tilting at that windmill... For me, the one that drives me nuts is "21's handle better than 19's!!!" Never mind that those 21's come with high-performance summers and the 19's with (relatively) lousy all-seasons... :rolleyes:
     
  12. green1

    green1 Active Member

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    As I have not yet bought my S, I always look at these threads to fine tune my selections, hoping for that bit of insight where someone actually did a fair comparison of one thing or other. And while occasionally such a thread arrises, the vast majority are "I changed a dozen things, but I'm sure that this ONE was the only difference!"
     
  13. MTOman

    MTOman Member

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    I had a coil suspension loaner (19") for a couple days, just got my car back from service this morning, and I could definitely feel a difference in the suspension. I drive the same route all the time so I know what certain parts "feel like" and, while I wish I could say one is softer and one harder, for me it felt like it depended on the kind of bumps I was hitting - sometimes the coil felt softer than my air suspension and sometimes it felt harder. Neither feels soft like you're floating, I don't believe the MS suspension is designed to give you that cloud feeling.

    The biggest difference to me was the feeling when cornering around a highway ramp, it's hard to describe but the coil suspension didn't give me the "feedback" I feel with my air suspension so I wasn't willing to push it as hard as I do with mine. I'm sure you get used to what you have and that's probably part of it, but there was a clear difference. Part of it could also be due to the auto lowering, mine happens at 55 and seems to tighten up the car a bit - makes it less cushiony but gives more feedback - so it's possible if I took the same highway ramp in standard height it would feel more like the coil, I haven't tested this theory yet ;)

    If I could go back and buy my car again I'd still go with the air suspension. Not only do I prefer the way it feels overall, I also like lowering it at highway speeds and being able to raise it when I need to. If I knew more about cars maybe I would prefer coil because you can tweak it but for me air suspension was a good decision.
     
  14. 3mp_kwh

    3mp_kwh Member

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    "Never"? I think you are nit picking. He made the more common call that coils are a bit "rougher", and that is the theme. Also has been the theme of these threads, that air is not as connected in cornering. It's good people write their comments over how they controlled for their observations, like "same ride to work". It shows what they were looking for, as much as how dissimilar the wheels were, etc. My gut, and the other posters here who track cars (at least three in this thread, counting myself) seems to be that coils are more reassuring, if you are pushing the limits in turns. In MTOman's case, I suspect it may have been the higher roll-center of the coil car. Coil cars sit higher. This isn't a vehicle, in the first place, to seduce one's cornering skills and those not compelled to do so are probably wise to choose air. In my case, I only tested an air car and on that basis, the postings of lolachampcar, and the service of air suspensions, I'm confident I want coils. Like you, I haven't got one. The Tesla is a ~4,800lb car, giving regular old coils an easy go at providing a smooth ride.

    I am less trying to provide an opinion regarding air/coils, than I am attempting to connect the dots of who usually goes for what. Despite what others say, I don't think there's too much owner bias to find a landing on this choice.
     
  15. Niclas

    Niclas Member

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    I also think, just as lolachampcar, that a lowered car on coils is superior than air, performance wise. Of course, with 21" michelins.
    Air suspension also adds a bit of diffuse steering feeling around the center.
     
  16. Gizmotoy

    Gizmotoy Active Member

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    Pretty much echos my thoughts. I don't have any track time in the Model S yet (Laguna this weekend), but I have been involved in a pretty good amount of suspension tuning, including a formerly souped-up (California :cursing:) Evo that saw lots of track time. I've posted my story before, but I'd probably be in a Panamera if coils weren't an option.

    That's not to say air isn't great. I'll freely admit there have been a half dozen times or so I've wished I could go "Very High" for piece of mind, though as it turns out I've never truly needed it. For me, though, I found the steering already pretty numb relative to my prior vehicles, and felt the added communication of the coil suspension crucial to my enjoyment of the vehicle in the turns. I wish it sat maybe 0.5 - 0.75" lower, and I wish Michelin made the Super Sports in the 19" sizing, but other than that I've been extremely happy with it.

    I've said it before, though, this is hugely subjective. If you're at all curious, ask to drive both back-to-back, or see if a nearby owner will take you for a drive.



    I'm not sure lola'd agree with the bolded part, and has suggested 19"s and 20"s in the past. Those 21"s are heavy. The sweet spot is really in the 19" - 20" range, depending on tire options in chosen sizings. For now, the pretty much means 20" for us as we have a rarer sizing, unfortunately.
     
  17. DIL

    DIL Member

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    #17 DIL, Jul 17, 2014
    Last edited by a moderator: Mar 13, 2016
    Sweet! I have such fond memories of the corkscrew. Last time I did it in an ISF and it was sublime. Do this with your Tesla and report back: Alex Zanardi Laguna Seca Cork Screw Pass - YouTube

    Super Sports would be epic. Michelin, make them in this size!
     
  18. tga

    tga Active Member

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    <sarcasm>
    Oh, but Tesla put 21's on the P85+, so they must be better! How dare you question Tesla's wisdom?!?! They've clearly figured out a way to break the laws of physics with their suspension design - their engineers are that good!
    </sarcasm>

    (That was pretty much the response I got over on the factory MS forum when I dared to point out the concept of "unsprung weight":biggrin: )
     
  19. HyperMiler

    HyperMiler Member

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    They make the PSS in 255/45 19 R 100. Close enough?!
     
  20. robo45h

    robo45h New Member

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    I know this thread is a year old, but I'm looking at buying a Model S, and so here I am. Unfortunately, most of the comments comparing the coil vs. air suspension seem to focus on how bumpy the ride is. I currently have an Audi S4 B6 (V8) with a very stiff ride; I don't care how bumpy it is as I'm not here for a luxury ride (I would buy Model 3 instead of the "luxury car" S if the 3 was currently shipping). So what I'm interested in is handling -- not on a straightaway, but on twisty, hilly, country roads.

    Any input?
     

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