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01-18-2017, 11:01 PM | #1 |
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Signal Green M3 and Performance Air?
Yeah, I am trying out air suspension. I have my reasons. Before I get to that here is a disclaimer.
I REALIZE CURRENT AIR SUSPENSION SYSTEMS WILL NEVER COMPETE WITH A QUALITY SET OF COILOVERS. -Please read my comments before making any generalized statements. I would like to try and avoid too much hate in this thread. I realize what I am doing is a downgrade in performance from my KW Clubsports. I also want to avoid "air disciples" from spouting propaganda that is also unfounded. I have always considered air suspension an undesirable modification. A huge downgrade in performance. However, after my move to Texas, the impracticalness of my car became even more apparent. Terrible roads and construction in my area made driving my car a nightmare. While at SEMA 2016 I had to chance to view some the latest advancements in hydraulic lift systems for coilovers and current air suspension systems. Both hydraulic lift systems and air suspension offer the ability to quickly change ride height. Both require routing of hydraulic or pneumatic lines, both come with a weight penalty, and both require support equipment to be mounted in the car. However, air suspension allows the ability to drive at speed at multiple different ride heights. Though, there is a performance sacrifice. My question, how much of a sacrifice? The internet is very two sided on the performance of an air suspension system. There is a lot of hate, a lot of unjust praise, and very little worthwhile discussions on the subject. It doesn't help that a lot of air suspension systems are sort of pieced together, using sketchy parts, with sketchy installations, with disastrous and terribly performing results. However, love them or hate them, modern air suspension has come a long way. The prospect of being able to adjust ride height on a whim and still maintain a certain level of performance, hopefully, is/was too much for me to pass up. With that said, I wanted to give an honest review of air suspension on a performance car. A review of the kit, the installation, and eventually the performance on the street and track. I am not affiliated with any companies and I have nothing vested in air suspension. In fact, I plan on keeping my KW CSs as a back up. I don't care to hear anecdotal evidence. I am doing this to find out for myself. If you have installed an air suspension, tracked on it, and see anything I could do differently or better, please comment. If you are reading this because you are curious, like I was, enjoy. I chose the Airlift Performance 3P/H kit for this build. I will go over the reasons but there are is some background you have to understand about air suspensions. Air suspensions come in many flavors. I like to use the analogy that air suspension setups are like car stereo installs. Every air suspension has the same basic components, like a car stereo system, but the quality, install, and setup of those components can yield very different results. With that, air suspensions can have sleeved or bellowed bags, bags over coilover (BOC), standard bag on strut/shock, digital management, analog/manual management, digital pressure only management, digital pressure and height management, digital height management, single or multi tank, single or multi air compressors, hard line etc etc.... The performance I am hoping for is probably not achievable without digital management of some kind. Since I also want a reliable alignment, a concern when dealing with air suspension due to the varying ride heights, I decided I needed digital management that included height sensors. Height sensors will get the car to the desired height with a very high level of precision and accuracy. There are quite a few manufacturers that offer digital management with height sensor monitoring. Keep in mind, many of the air suspension systems you see on the street or at shows are using "pressure only based systems". They are easy to install because you don't have to install ride height sensors and run sensor lines all over the car. But they are not as good at getting the car back to the aligned ride height. Because, depending on the day, the same pressure will not yield the same ride height. Pressure, however, is what I will be using now instead of spring weight, so pressure matters. The Airlift 3H/P system is one of the few, that I found, that offers both height sensors and the ability to monitor pressure. I borrowed the below image from Speedhunters and it shows the cutout of a typical Airlift coilover based air suspension. They use modified BC coilovers that allow for some of the peculiarities of an air spring. Speedhunters-Keith-Charvonia-SEMA-Aftermarket-29-1200x800 by JEllis, on Flickr I contacted a supplier and air suspension specialist and explained what I wanted. They recommended a small air tank and a single compressor. Since I don't really care about the "aired out" or "stanced" look and really just want to occasionally manipulate my ride height to get into driveways or over bad roads. The full kit was delivered within a few days. IMG_1141 by JEllis, on Flickr IMG_1144 by JEllis, on Flickr Again, like a stereo install, you have to pre-plan where you want to put everything. The problem is that I have never installed an air suspension system before. I found it was easier to just jump in and take my time. I decided before I started the install that I didn't want to drill or permanently modify/hurt the car in anyway. I was able to find quite a few un-used plugged holes in the base of the E92 M3s trunk to use to eventually route the air and sensor lines. Below is an example. IMG_1147 by JEllis, on Flickr Raw material for future fab work. IMG_1148 by JEllis, on Flickr Ready for install IMG_1159 by JEllis, on Flickr IMG_1160 by JEllis, on Flickr IMG_1161 by JEllis, on Flickr I cannot stress enough how important a good thread sealer is. I initially decided to use Loctite 565 thread sealer. I had some issues later on and switched to the much cheaper, much easier to get, yellow teflon natural gas thread sealer tape. Tape is much cleaner and easier to get a seal. Just make sure to wrap it clockwise around the threads of the male end. Otherwise the tape will unravel as you tighten. As the car sits today, I am using a mix of Loctite and teflon tape. I will probably eventually replace all the seals with yellow teflon tape. IMG_1163 by JEllis, on Flickr IMG_1164 by JEllis, on Flickr I did a fitment test early on to make sure the wider bags would clear my wide wheels and tires. Good news is the bags sit up in the wheel well, above the wheel. You can run a very aggressive front wheel/tire combo with this air suspension setup. IMG_1166 by JEllis, on Flickr IMG_1167 by JEllis, on Flickr KW CSs coming out. Along with the rear control arms. The rear control arms are replaced in order to mount the air spring securely and to ensure that the bag does not rub on anything. The only way around this is to use a "sleeve" type air spring. The problem with sleeve type air springs is that they "crumple" at low pressure and will rub on itself and its collars. Air springs, like tires, will hold air as long as something isn't rubbing or digging into them. Airlift did a good job making sure their components properly seated the air spring away from anything that could be threatening to its integrity. IMG_1170 by JEllis, on Flickr IMG_1173 by JEllis, on Flickr Airlift provides replacement eccentric bolts, I marked the old bolts orientation for future reference. I figured it would help get the alignment close for the initial test drives before taking the car to the shop for a full alignment. IMG_1171 by JEllis, on Flickr IMG_1172 by JEllis, on Flickr Below you can see some of the new hardware Airlift provides. IMG_1176 by JEllis, on Flickr
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01-19-2017, 06:30 AM | #3 |
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Air ride has its ups and downs (lolz)
I ran the Airlift performance kit on my old mkvi GTI and I loved it. I never got any toad course time with the kit but I did still drag race the car with the bags which worked pretty well. I was running the older V2 management at the time since P3/H3 did not exist. My biggest issue with the kit was the lack of travel in the suspension, but this is more of an issue with the kits on VWs, not sure if the bmw kits are the same way. If you wanted to be able to air down until the car bottomed out your max height was still lower than stock height and that was with the front struts topping out. Like you said, a clean install makes a world of difference. I have installed about 10 kits now on different cars and rarely have issues. I see some people that have problems (leaks mainly) a lot but its mostly from a half assed install.
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01-19-2017, 07:50 AM | #4 | |
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I have been working for the last three weeks. The car is finally on the ground but I need to get it aligned and work out some bugs.
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Back to the build Here is a look at another OEM hole in the trunk that drops into the rear wheel well. Perfect for routing lines. IMG_1183 by JEllis, on Flickr The most time consuming part of the build was the design of the height sensor mounts. Again, I didn't want to drill into the frame of the car so I came up with brackets that used OEM holes or studs. All the brackets were cut out of sheet steel with a jigsaw and dremel. Not the prettiest pieces but not bad for the tools I had. If I keep the air suspension, I will have some professionally made. Anyone want some trick height sensors for an E92? I mocked them up in cardboard first IMG_2926 by JEllis, on Flickr IMG_1187 by JEllis, on Flickr IMG_1179 by JEllis, on Flickr Here are the front and rear height sensor brackets ready for install and coated with black caliper paint. IMG_2994 by JEllis, on Flickr With height sensors attached. IMG_1197 by JEllis, on Flickr I think it would be really awesome if Airflit or some other air suspension company could figure out how to hijack the OE height sensor signals from the HID levelers. I feel like this should be possible.
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01-19-2017, 08:06 AM | #5 |
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anxious for your review! i've traditionally been a coilovers guy and went as far as purchasing the 3h kit for my audi... ended up selling it and going with coilovers. i'm in the same position as you, not looking the slam the car but the possibilities with on demand adjustment can't be beat.
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01-19-2017, 08:11 AM | #6 | |
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01-19-2017, 08:15 AM | #7 |
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Thanks for sharing. Was surprised to see you doing this on instagram, but seeing you did not make any crazy modifications to the car (drilling etc) explains it!
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01-19-2017, 09:23 AM | #8 |
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Are you going to model the toe curves to figure out what happens to toe at what ride heights within the range you're going to use? That'd be my biggest concern with running on demand ride height change you have to be ready to drive around a very different setup from a front toe perspective depending on ride height since it has Such a Big effect on cornering attitude
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01-19-2017, 09:29 AM | #9 | |
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01-19-2017, 11:37 AM | #11 | |
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Also, it should be noted that air pressure in the bag is very important to performance. The BC struts are little shorter than OEM in order to allow higher pressures at lower ride heights. Its not a huge difference, 10psi or less but its something to be aware of. If I decide to stay on air, I am going to look into a higher quality coilover with customized internals to accommodate air. KW, Ohlins, Moton, JRZ, or BC Race are options in this regard.
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01-19-2017, 11:41 AM | #12 |
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This is awesome and I like that you wanted to venture out and find out for yourself, not anyone else. I always wondered about air vs coilovers and I like your perspective. Solid work as always.
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01-19-2017, 12:19 PM | #13 |
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Interesting. I bet a higher quality damper would make a pretty substantial difference in performance over the Airlift damper.
From your research and such you wouldn't recommend putting bags on the KW CS? For functionality rather than the 'bagged" look? I am running KW CS now and want to switch to air for the adjustability on terrible LA roads. Thanks for you time. |
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01-19-2017, 12:27 PM | #14 | |
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Bottom line, I will be able to answer this better when I completely finish the installation and have the car setup properly.
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01-19-2017, 05:54 PM | #16 |
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Air is good.
I like air. I've had ZERO problems with any of my air setups (3 out of my 4 cars are on air ride). You'll love it. Also, good look on the single compressor and tank. It doesn't make THAT much of a difference in airing up. I go from 0 psi to my ride height in a couple of seconds tops. I ordered dual compressors, but only installed one. It's nice to have a back up in the unlikely event that one gives out. Let me know how you like 3H. I did 3P because when I bought/installed, the new ALP stuff was VERY new. I heard that a few people had some issues with 3H and snapping levelers. Alllllsoooo... I had some MAJOR weird issues with the rear passenger's bag and plate spinning. Turned out, after lots of freaking out, grinding down the retaining plates, etc that it was the nerfy, spongy material that BMW uses for their subframe bushings. Some Delrin/Aluminum stuff from Turner Motorsport took care of that. I had originally marked the bag plate and the control arm to measure how much it was spinning BEFORE we figured out what it ultimately was...the bag had almost spun around completely. Haha...I'm sure Blake at Air Lift remembers our conversations with me bugging out.
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I did a lot of things to it. Last edited by Raek; 01-19-2017 at 06:27 PM.. |
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01-19-2017, 08:56 PM | #17 |
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I have lots and lots of experience with air.
MKV GTI, 987.1 Cayman S, W204 C63, MKVI Golf, etc. AirLift is, in my opinion, the best bags you can buy. AirRex is a close second, but I personally like AirLift more. I think ACCUAIR ELevel is better than the AirLift 3H, but that's just my opinion. I've used ELevel many times. A clean/good install makes air very reliable. I personally would run a dual compressor setup. Mainly because you'll have one that works in case one dies, and, it also charges faster. I didn't like having to hear my compressors all the time. Feel free to shoot me a message if yo uneed any help with the air, excited to see how it all looks after! |
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01-20-2017, 08:16 AM | #18 |
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One more post, haha...
This is what was happening. I was getting this MAJOR squealing at ride height under load (my ride height is SLIGHTLY lower than factory...think an Eibach race kit). As stated, the bag was spinning as well as grinding against the axle. We shaved the lower retaining plate down to reduce contact: We marked the new setup, and I kept an eye on it: But, that still wasn't working. The bag was spinning, almost all the way around...to the point where the line was in threat of being severed. We took the rear bags out and noticed that the upper nutserts were being ripped out! I contacted about 5 other bagged E92Ms via Instagram...and, FOUR of them were having the SAME problems. After a bunch of research on the whole system back there, I found out that BMW uses HORRIBLY squishy bushings (my car only had about 15k on it at the time). Hence the upgraded stuff. So...keep an eye out. I don't know if you have any upgraded bushings, but you track the car...so I'm guessing you do.
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01-20-2017, 09:12 AM | #19 | |
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01-20-2017, 10:16 AM | #20 |
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I do not understand how tuners or DIYers can do a quality air installation in a matter of hours. In my opinion, even the most accomplished installers need a full day or two to get the install right. This is yet another reason why air, in my opinion, has such a bad reputation. The air lines are relatively fragile. The importance of thinking out a good path for the lines cannot be over stressed. It is also important to make sure the lines are well protected. I ordered a bunch of goodies from the McMastercar for this build. There was a steady stream of hardware coming to the house.
IMG_1184 by JEllis, on Flickr You can see the corrugated plastic sleeves and protec anti abrasion sleeving that I used just about everywhere to ensure the air lines and sensor lines would be well protected. IMG_1190 by JEllis, on Flickr Where I the airlines were going to be relatively secure, I used only Protec sleeving. Where the lines were somewhat vulnerable would be vibrating against other parts of the car, I used the plastic sleeving or a combo of both. IMG_1192 by JEllis, on Flickr You can see a combo of both here. On the passenger side of the car I ran out of OE holes and routed lines through the pressure relief flap above the battery. Not my favorite solution but good enough for this purpose, and better than drilling into the car. IMG_1193 by JEllis, on Flickr More to come....
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