A suspension's primary function is to absorb bumps and keep the tires planted through all the driving conditions you put it through. Of course there are some tradeoffs involved here. And many of you who want to improve the Elantra's handling capabilities will probably want to stiffen the suspension. Conventional wisdom says that extremely high spring rates are the way to go about it, and the tradeoff will be poor ride quality on the harsh streets you drive on everyday. I want to dispel that myth, and offer suggestions for a suspension you'll be happy with for daily driving, 'spirited' driving, and even track use.
Springs & Dampers
When you install lowering springs with stiffer spring rates you should ideally upgrade to a damper with higher rebound damping rates to achieve better control. When you ignore the struts you can wind up with a bouncy, uncomfortable and poorly damped ride. With mild spring upgrades such as Eibach and H&R this may not be entirely necessary since they aren't too bad on the stock struts. But a damper upgrade is something you should at least keep in mind if the ride quality and control doesn't turn out like you hoped.
The other thing you should be concerned about is the effective suspension travel of your suspension. If your car is lowered excessively it can easily bottom out on the bump stops over bumps, which can ruin the ride quality and even cause the car to skip and hop and lose control over a midcorner bump. Along those lines, I haven't even mentioned full coilovers yet and I won't dwell on them too long. But the very nature of all the available height adjustable coilovers is that they reduce suspension travel a lot. Combine that with the fact that they are fitted with much higher spring rates than the lowering springs available, and you're in for an uncomfortable ride. So I've ruled them out for the purpose of daily driving.
As for choosing your dampers, you get what you pay for to an extent. One thing you should know is where the dampers are being developed. It's a difficult task to develop valving for a damper that produces smooth damping curves at different velocities and frequencies. And the best of the best are the companies that do their development on the most demanding roads.
The truth is that many aftermarket dampers are developed in Japan where both their roads and their race tracks are typically very smooth. So they have a certain damper tuning style along with very high spring rates which work fine on their roads but not so well in Europe and America. KYB is one such company based in Japan. I've found that most of their products don't absorb bumps or damp oscillations as well as their European competition. The big advantage of course is they sell a very cheap product which is similar to OEM-quality.
But on the European side of things there are companies like Koni and Eibach. Koni has been developing dampers since 1932 and doing their R&D in The Netherlands. They make the Koni Yellow strut inserts for the Tiburon, which have adjustable rebound. The most practical way to install these would be to buy a used set of '03+ Tiburon struts, then buy the Koni inserts to install in the struts. The only thing different about installing Tiburon struts on the Elantra is that you need to swap the front left and front right strut because the brake line brackets are on opposite sides. This is a lesser-travelled upgrade path because of the extra work involved. But these dampers are a very popular option for many applications because they work great for lowering springs thanks to the rebound adjustability. They are also the most expensive option.
And then there's Eibach who does their R&D in Germany but they are relatively new to damper tuning by comparison. I'm not sure if Eibach actually manufactures their own dampers or not. Eibach may in fact outsource the dampers to be manufactured by another company but they claim to do the development & testing themselves. But they have the Eibach Pro Dampers for the '03+ Tiburon which is a non-adjustable complete strut replacement.
Anti-sway bars
The beauty of tuning with sway bars is that you can reduce body roll without taking much away from the comfort of the car. So if your lowering springs don't reduce body roll enough for your tastes, it's usually a good idea to at least upgrade to the 19mm Tiburon rear sway bar. This will drastically reduce bodyroll and reduce understeer. You may also want to consider the Whiteline rear sway bar, or the 22mm Eibach rear sway bar.
But if you want even more roll resistance you can upgrade the front sway bar as well. Many people don't like the idea of installing a stiffer front sway bar because it'll increase understeer (something this car doesn't need more of). However that's not the whole story. There will be more understeer during turn-in, yes. But steady-state understeer will actually be reduced due to less camber loss. So corner speed can actually benefit from a stiffer front sway bar, you just have to use a classic driving style to take advantage of it. For example, flicking the car to get the back end to step out won't be as effective with a stiffer front sway bar. But in most cases that won't help things anyway. Typically you'd be better off slowing to the right speed for a corner, and trail braking and turning in smoothly to get the most speed out of a corner.
The only front sway bar upgrades available are for the Tiburon so to do this you'd need Tiburon struts which have sway bar mounting brackets on them. You'd have to install the struts left for left and right for right, and you'd need to fabricate brake line brackets since they are on the wrong sides.
Alignment settings
You can realize big benefits in corner speed with some alignment changes, however you probably don't want to sacrifice tire life if this is your daily driver. Contrary to popular belief, the Elantra can actually ride on some pretty aggressive negative front camber as long as you keep the front toe settings at 0. You can set some aggressive front camber settings if you install Eibach camber bolts.
I would suggest settings like these:
Front camber: -1.2 to -2.0 degrees
Front toe: 0
Rear camber: -1.2 degrees
Rear toe: factory
Springs & Dampers
When you install lowering springs with stiffer spring rates you should ideally upgrade to a damper with higher rebound damping rates to achieve better control. When you ignore the struts you can wind up with a bouncy, uncomfortable and poorly damped ride. With mild spring upgrades such as Eibach and H&R this may not be entirely necessary since they aren't too bad on the stock struts. But a damper upgrade is something you should at least keep in mind if the ride quality and control doesn't turn out like you hoped.
The other thing you should be concerned about is the effective suspension travel of your suspension. If your car is lowered excessively it can easily bottom out on the bump stops over bumps, which can ruin the ride quality and even cause the car to skip and hop and lose control over a midcorner bump. Along those lines, I haven't even mentioned full coilovers yet and I won't dwell on them too long. But the very nature of all the available height adjustable coilovers is that they reduce suspension travel a lot. Combine that with the fact that they are fitted with much higher spring rates than the lowering springs available, and you're in for an uncomfortable ride. So I've ruled them out for the purpose of daily driving.
As for choosing your dampers, you get what you pay for to an extent. One thing you should know is where the dampers are being developed. It's a difficult task to develop valving for a damper that produces smooth damping curves at different velocities and frequencies. And the best of the best are the companies that do their development on the most demanding roads.
The truth is that many aftermarket dampers are developed in Japan where both their roads and their race tracks are typically very smooth. So they have a certain damper tuning style along with very high spring rates which work fine on their roads but not so well in Europe and America. KYB is one such company based in Japan. I've found that most of their products don't absorb bumps or damp oscillations as well as their European competition. The big advantage of course is they sell a very cheap product which is similar to OEM-quality.
But on the European side of things there are companies like Koni and Eibach. Koni has been developing dampers since 1932 and doing their R&D in The Netherlands. They make the Koni Yellow strut inserts for the Tiburon, which have adjustable rebound. The most practical way to install these would be to buy a used set of '03+ Tiburon struts, then buy the Koni inserts to install in the struts. The only thing different about installing Tiburon struts on the Elantra is that you need to swap the front left and front right strut because the brake line brackets are on opposite sides. This is a lesser-travelled upgrade path because of the extra work involved. But these dampers are a very popular option for many applications because they work great for lowering springs thanks to the rebound adjustability. They are also the most expensive option.
And then there's Eibach who does their R&D in Germany but they are relatively new to damper tuning by comparison. I'm not sure if Eibach actually manufactures their own dampers or not. Eibach may in fact outsource the dampers to be manufactured by another company but they claim to do the development & testing themselves. But they have the Eibach Pro Dampers for the '03+ Tiburon which is a non-adjustable complete strut replacement.
Anti-sway bars
The beauty of tuning with sway bars is that you can reduce body roll without taking much away from the comfort of the car. So if your lowering springs don't reduce body roll enough for your tastes, it's usually a good idea to at least upgrade to the 19mm Tiburon rear sway bar. This will drastically reduce bodyroll and reduce understeer. You may also want to consider the Whiteline rear sway bar, or the 22mm Eibach rear sway bar.
But if you want even more roll resistance you can upgrade the front sway bar as well. Many people don't like the idea of installing a stiffer front sway bar because it'll increase understeer (something this car doesn't need more of). However that's not the whole story. There will be more understeer during turn-in, yes. But steady-state understeer will actually be reduced due to less camber loss. So corner speed can actually benefit from a stiffer front sway bar, you just have to use a classic driving style to take advantage of it. For example, flicking the car to get the back end to step out won't be as effective with a stiffer front sway bar. But in most cases that won't help things anyway. Typically you'd be better off slowing to the right speed for a corner, and trail braking and turning in smoothly to get the most speed out of a corner.
The only front sway bar upgrades available are for the Tiburon so to do this you'd need Tiburon struts which have sway bar mounting brackets on them. You'd have to install the struts left for left and right for right, and you'd need to fabricate brake line brackets since they are on the wrong sides.
Alignment settings
You can realize big benefits in corner speed with some alignment changes, however you probably don't want to sacrifice tire life if this is your daily driver. Contrary to popular belief, the Elantra can actually ride on some pretty aggressive negative front camber as long as you keep the front toe settings at 0. You can set some aggressive front camber settings if you install Eibach camber bolts.
I would suggest settings like these:
Front camber: -1.2 to -2.0 degrees
Front toe: 0
Rear camber: -1.2 degrees
Rear toe: factory
