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Buyer’s Guide: Choosing the Right Coilovers

If you’re looking to replace a worn suspension, improve your car’s handling, or just slam it to the ground, coilovers are a must-have. There are several different brands, styles, and types out there, and we are asked daily which kit is the best route to go for.

Which setup you choose is really more about what you plan to do with the car. The most expensive kit is not always going to be the best option. There are a few things to keep in mind while shopping.

Upper Mounts: Rubber vs Pillow-Ball vs OEM

Most coilovers on the market will use a pillow-ball upper mount. This means a spherical bearing is used as the joint between the strut assembly and the top-hat, where it mounts to the car. A pill0w-ball will produce sharper, more precise handling, but it will also transmit vibration and harshness through the suspension more easily, producing a harsher ride on the street.

Pillow-Ball vs Rubber Mounts

Many newer brands are offering rubber upper mounts. These provide a slight amount of deflection, compared to pillow-ball. While virtually of them will be stiffer than a stock setup, a coilover using rubber mounts will be much more streetable than one using pillow-ball mounts. Here are some popular coilovers and which mounts they use:

Additionally, some coilovers, like the Tein Street Advance and KW Variant 3s, forgo the inclusion of upper-mounts altogether, and instead you just re-use the upper mounts your stock suspension uses. Because the stock suspension uses a large, rubber spring seat, this will almost always offer the smoothest ride, but is not always the best choice for performance.

The Tein Street Advance Coilovers re-use your stock upper mounts.

 

Helper Springs

Coilovers are generally all adjusted the same way. You loosen the lock collars at either end, and twist the main threaded shock body (sometimes called the “cartridge”). Twisting the shock body effectively screws it into the lower mount (called the “cup”). Screwing it further into the cup will lower the car, and unscrewing it will raise the car. If you’re looking to go extremely low, you may find that the car isn’t as low as you like once you screw the shock body into the cup. The only way to go lower from here is to unload the spring.

When you unload the spring, by spinning the spring’s lower mount around the threaded shock body, you create a condition called “droop”. This means the spring is basically loose; you can physically jiggle it around. But when you set the car on the ground, the shock compresses and sits on the spring like normal, and the result is that the car is now lower.

Droop can be a dangerous condition, however. If you hit a large bump, the spring can free-float between the upper and lower mounts while the coilover is unloaded, and there’s nothing forcing it to land correctly. So once the coilover compresses, the spring may land incorrectly, causing serious damage.

Helper springs are thin, light springs that are installed between the main spring and the spring mount. They are easily compressible, and exist purely to let the car go lower. Keeping helper springs in place means that even if the main spring is unloaded during driving, the helper spring will stretch out to maintain constant tension on it, keeping it in place to ensure it will land correctly. This gives you the benefit of lowering the car more, but negates the dangerous side-effects of you would otherwise get from the “droop”.

Powertrix SS Coilovers include front + rear helper springs out of the box.

Powertrix SS Coilovers include front + rear helper springs out of the box.

Some coilovers today include helper springs out of the box, like the Powertrix Sport Street, and Stance SS+ (the “plus” versions are exactly the same as the regular SS, just include helper springs), but most can be added down the line if desired. They are available from Stance and Powertrix, but are compatible with most other brands.

 

OEM-Type vs “True” Coilovers

This won’t apply to Z32 guys, but the “VQ” generation cars (350Z, G35, 370Z, etc) use a separated rear spring and shock. The spring sits in a cup on a control arm, and the shock mounts to spindle and body of the car. Many coilovers are available in both styles. Neither is truly superior to the other, though many feel a “true coilover” setup is a better choice for a car where performance is a higher priority. This is partially because switching to a true coilover setup allows you to replace the rear control arm which otherwise houses the bulky, heavy, spring seat.

Stance SS Coilovers are available in both "true coilover" and "OEM style" (Pictured).

Stance SS Coilovers are available in both “true coilover” and “OEM style” (Pictured).

There is some debate surrounding which choice is better, but it really just comes down to personal preference!

Spring Rates & Valving

Perhaps, the most important thing to consider when buying coilovers is the spring rate. The spring rate is the rate of compliance of the spring. A higher number will produce a stiffer ride, but better handling. And the reverse is true, lower spring rate will lead to a softer ride, but a bit more body-roll under hard cornering.

Some coilovers give you the option of selecting a spring rate, and virtually all allow you to change the springs completely in the future if you like to. This is a great feature if you decide you want to move up to a stiffer spring rate or down to a softer one, but it should be done with some prudence. You can generally move about 2k/kg in each direction safely before the shock needs to be re-valved. Otherwise, you end up with a coilover that gives you either a bouncy ride or an overly harsh ride.

Additionally, most coilovers for our cars will intentionally run a stiffer spring rate up front, and a softer spring rate in the rear. This is because rear wheel drive cars are generally prone to oversteer, and running a slightly softer setup in the rear helps reduce this. You might come across some coilovers with a stiffer spring rate in the rear. These are generally aimed towards drift cars, and is not ideal for a street-driven car, as they will induce oversteer a bit more easily.

Nick Letsom

25 Comments

  1. I have a 2014 370Z NISMO. Stock performance shocks give it great handling but a very bouncy ride. What can I do for this? I do not race the car so I would like to keep it low as it is but improve the ride without compromising too much of the performance.

    Thanks
    James

    • When you say bouncy, do you mean it follows the road too closely, or the car actually bounces up and down after you hit a bump? A lot of times, people misinterpret stiff suspension for blown shocks, but it is also possible you just have blown shocks, depending on what’s happening. Realistically practically any after market coilover will lead to a stiffer ride than stock, but there are some streetable combos out there. For the 370Z, Swift Springs are extremely popular.

  2. I would like something similar to the TEIN type flex control master as I liked how they act in a friend’s evo? any similar setup?

  3. I’ve been doing research but still not much closer to choosing a coil over kit.
    Price= not over $1,400 maybe $1,500 if really worth it, under $1,400 would be better.
    Ok so, it needs to be able to definitely sit right at tire level, no wheel well gap, good quality, and not need spacers for the rear wheel to fit ( plan on running wider rims and dont want to lose any room).
    Want adjustable dampening.
    Please help, I’ll be ready to buy come next week.

  4. What is the best adjustable coilovers for my 2012 Subaru XV? Any suggestions?

  5. First of all, the information you write up really good. I need your advice which suspension should I replace for my Alfa Romeo 159? But I still need the comfortable of ride because my wife is pregnant 😉 thank you in advance

  6. Looking for advice for an 09 G37 convertible. I want to close the gap between the tire and wheel well.(Its only about an inch to an inch and a half) I also don’t too harsh of a ride.

  7. I bought the Powertrix UL coilovers with swift springs a couple years ago for my z32 with 8k/6k. The ride is a bit harsh honestly. I was considering moving to KW V3s for a better ride and quality and considering getting 7k/5k or should I just leave the 8k/6k. Car is a weekend fun toy with ocassional tracking but mostly street fun and crusing. I just don’t like the harsh ride especially over bumps. I have the dampening softened up about 8 clicks from full hard too…I’ve adjusted them softer but then it gets really mushy and bouncy.

    • Ultra-Lites are track coilovers, I would expect them to ride harshly! They’re also not ideal for street driving because the aluminum tubes, while light, are going to be easier to warp and start leaking compared to steel tube designs. But that said, 8k/6k is fairly conservative for those. I would make sure your preload isn’t too high, they require very little. The ULs will be harsh no matter what because of the pillowball mounts. The same setup on SS would be a lot easier. But honestly I run my SS at the first click and they’re good there 🙂

  8. i have a 1990 300zx 2+2 and cant decide what coilovers i want. some say that the pillowball mounts allow easy camber adjustments without the need for camber kits. im just curious on how that works and if its works on all 4 wheels. i dont want much camber only about -3 degrees. i also want a coilover that is great for daily driving but can also hold up on a track and perform well.

  9. Hello, I am modifying a 2002 350z into a full out race car and need some advice on what coilovers to go for and what spring rates would give me the best track handling (not drifting). Appreciate any advice given. Thanks

    • You don’t really need exceptionally high spring rates or anything for track use. In fact you don’t always want to go too high as you reach a point where the car can become unstable over uneven surfaces. I would say something around 12k/10k would be about right for most track applications. The rear spring rate will also depend on if you go true style or OEM-style. In OEM-style, the spring sits closer to the fulcrum, so it will generally need a higher spring rate to produce the same amount of resistance between the wheel and chassis.

  10. Hey, I have a RWD 08 G37S and I’m looking for Coilovers with the best ride quality, but I prefer to get “true” Coilovers and delete the spring perch. I would prefer to spend $1500 or less since I daily drive and never track the car. What would be your best recommendation? Thanks.

  11. I bought twin coil overs from Japan off a skyline for my z32, I’ve also replaced installed the energy suspension master bushing kit. The
    Ride will beat you up, bouncy as heck, I’m looking at ten flex Z kit next. Will this help with how bouncy the car is?

  12. I have a 2006 350z, I am going to buy some BC coilovers but do not know whether the rear are Oem or True coilovers, can someone help?

    • With BCs, the true coilovers will lower you more out of the box, and they’re a bit easier to adjust. They also give you the freedom to replace the spring bucket arm with a proper toe arm, which is the best way to adjust toe on the 350Z. But even with OEM style, you can still adjust the toe through eccentric bolts (like SPC’s), or traction arms, but it’s less ideal than a true toe arm.

  13. I have an 07 350z, sitting on OEM suspension. Just looking for something to lower the car nicely and be comfortable as the will be my DD. Any opinions… ?

  14. I like how you mentioned that there are several different kinds of coil over kits and that getting one isn’t just about picking what part works best with your vehicle. The choice of selecting the correct coil over spring kit can potentially replace a worn suspension and save it fees from car repairs. If I were given the chance to use one of these coilover springs, I may potentially be able to improve a car’s performance.

  15. I am contemplating getting ICS true rear N1 coil overs for my 2004 350z, would I need to replace the spring bucket arm or make any other changes?

    • It doesn’t require you to, it just gives you the option to do so if you want a clean way to adjust your toe setting.

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