Now that you know about wheels and tires, the next important step is some good suspension. Suspension is what keeps your G30 riding smoothly and keeps your tires in proper contact with the road. The problem is factory suspension on most vehicles is made with the average driver in mind. It has huge amounts of travel and is extremely soft, making for a very cushy and utterly boring ride. With a nice set of lowering springs or coilovers you will not only have a much more responsive ride, your G30 will look amazing with your new set of perfectly fitting wheels and tires.
You not looking to spend much on suspension? Lowering springs are probably your best bet. They are super affordable, readily available, and they let you retain your factory electronic damper controls (if your G30 came equipped with them). They are also relatively comfortable, firming up the ride and reducing body roll while maintaining most of the factory ride quality.
If you’ve ever modified a car, you’ve probably heard of H&R. It’s almost guaranteed that if you have a vehicle made this century there’s probably an H&R Sport Spring Kit for it. H&R is always developing new kits for new applications so that within a few months of a new vehicle’s release there is usually a kit already available. These springs will give you a generous amount of lowering (1.3″-1.4″ front 1.2″-1.4″ rear depending on application) from stock and firm up the ride so you get a good amount of steering input and road feel.
Like H&R, Eibach is ever-present in the world of aftermarket suspension. They develop their Pro Kit Lowering Springs for nearly every vehicle out there so this is another company you can trust to know what they’re doing with lowering springs. With these you will get a similar amount of lowering to the H&R springs (1.2″ front and back), responsive handling, and a smooth sporty ride. Eibachs are in general softer and more comfortable than an H&R kit so if comfort is your priority you’d wanna go with these.
Dinan Performance Springs – M550i xDrive
If you’ve opted for the M550i xDrive and you want an extra bit of heritage behind your mods then say no more. Dinan has developed their own lowering springs specifically for the M550i xDrive, and when Dinan does something they do it right. These springs have been engineered very carefully and specifically for the M550i to improve the suspension’s ability to handle the forces of weight transfer, braking, and acceleration. It also improves the aesthetics of the vehicle immensely, giving a very even stance and minimal wheel gap. When the springs are paired with Dinan’s supplemental ride quality and handling kit you really get the full Dinan experience. These specially designed bump stops ensure optimal suspension travel and do not give a jarring feeling on big dips/bumps thanks to their progressive rate design.
First off, the term “coilover” can be a bit vague, so let’s give it a solid definition and then discuss why the actual definition does not matter in day-to-day conversation. A coilover is defined as a coil spring mounted around a shock body, quite literally “coil-over-shock”. If someone wanted to get nit-picky you could technically call a MacPherson spring/strut combo a coilover. However, “coilover kit” is the accepted term for an aftermarket suspension system consisting of a coil spring and a matching damper. Most times coilover kits will have adjustable spring perches and damper settings, but those are added features not encompassed in the term. Some coilover kits are not even technically “coilovers”, they utilize a separate spring and shock because that is the vehicle’s factory configuration. So there you have it, if anyone ever tries to correct you on your use of the term “coilover” you can kindly remind them that it is the accepted colloquialism in the industry. If they persist, just remember that you are an actual functioning member of society and responding to them is not worth your time.
BC BR Coilovers – 530i, 540i
The BC BR Coilover Kit is some of the best value for money you can currently get out of a coilover kit. For under $1000 you get full height adjustability, preload adjustability, front camber adjustability, and 30 way adjustable dampening (compression + rebound). You also have the option of upgrading to swift springs with custom spring rates if you are feeling ambitious, which can give you different ride and handling characteristics. These are a great option for anyone who wants to have some precise control over their ride height and dampening without getting too complex or breaking the bank. They are currently available for the 530i and 540i, no news yet as to when the xDrive and M550i kit will be released.
KW Variant 3 Coilovers – 530i, 540i (incl. xDrive)
KW is currently one of the biggest names in aftermarket suspension. The Variant 3 kit is a bit overkill for most people but it will undoubtedly be one of the highest quality parts you can get. The kit comes with coil springs, 16 way adjustable rebound, 12 way adjustable compression, and full stainless steel shock bodies for maximum corrosion resistance. You may be thinking “now hold on a minute, that’s not as much stuff as the BR kit” and you’d be right, there are no top mounts included with the KWs, and seemingly fewer adjustments. However, true value is in the quality of the parts and the tuning of the dampers. Sure the BR kit has almost twice as many clicks of adjustment but that doesn’t necessarily mean that every click is meaningful, KW has been doing this for a long time and there’s a reason they’ve stuck with their 16/12 click adjustments. It’s a simple case of “you get what you pay for”. Unfortunately if you have an M550i xDrive there is not a KW kit available yet, but they are constantly developing for new applications so be sure to check our G30 suspension page to see any new products available. Note: it is very easy to completely ruin your ride quality and handling if you make too many adjustments to this system without knowing what you are doing, we highly recommend using the KW recommended settings and then making very minor adjustments thereafter. Certain wheel/tire combos will require you to increase or decrease dampening based upon their weight.