Cars come with conventional-size and strength springs that help it deal with potholes and bumps on the road. Manufacturers have spent considerable time and money to come up with just the right suspension components.
Nevertheless, it has become fairly common for car owners to modify their cars’ suspensions to make them ride lower. Usually aesthetics are one of the most important reasons for reducing ride height- many people prefer the appearance of a lower car- but there are other advantages, as well as disadvantages.
Here are some of the pros and cons:
- Head-turning good looks.
- Handling (tire grip) can be improved by lowering the car’s center of gravity, which tends to reduce body roll and minimize skidding.
- Lowering the vehicle usually reduces aerodynamic (wind) drag (i.e., less air going under the car), which increases fuel economy, and sometimes reduces high speed lift, this making the vehicle more stable and faster. (These effects are usually quite small for realistic amounts of lowering.)
- A lower vehicle may pose less of a rollover risk, even if you hit a curb or some other road obstruction. (Most cars are extremely difficult to roll under normal conditions, so this is at best a minor consideration).
- Super comfort (i.e., better road feel) and less rattling.
- Suspension work should be done by a professional. Automotive springs exert thousands of pounds of force and if you don’t follow proper procedures when removing and reinstalling them they can cause serious injury or death.
- Any custom work or aftermarket parts will be expensive.
- The lowering process can change the camber (at rest, or when the wheel is raised as over a bump), which in turn has two negative effects, reduced traction, particularly for braking, and increased tire wear.
- Steering geometry may be changed enough that the car can’t be steered safely. This applies primarily to cars that have been lowered several inches or more.
- A car that has been lowered a great deal may bottom out at driveway entrances or be unable to clear normal road obstacles. Also, in the event you need to have your car towed you may find that it can’t be towed normally (a flatbed may be required) or that there’s no way to do so without damaging the car.
- Shock absorbers may experience more force (along their lengths or sideways), reducing their lives.
- Not all dampers are capable of dealing with radical changes in ride height.
- A lowered car may put extra stress on various other suspension and steering system parts, leading to excessive wear and even premature failure.
- Tires may rub against sheet metal or suspension parts, causing damage to both.
- The ride will almost always be harsher, as most lowering methods reduce spring travel. This can be uncomfortable for you and your passengers, and can also increase wear and tear as your car gets bumped and bounced harder.
Most of these problems do not result in serious danger to life and limb. The exception to that rule is extreme camber changes, which can reduce braking performance so much that they render the vehicle unsafe; there may be a “camber kit” available to prevent this effect, but it’s critical not to drive any vehicle whose camber has been grossly altered from stock. Similarly, it’s vital to ensure that the steering system functions properly after lowering. This isn’t usually a great danger if a car’s been lowered only an inch or two, but beyond that it may be necessary to make substantial modifications in order to ensure that the car is safe to drive.
Many of the other drawbacks can be reduced or eliminated by taking appropriate steps; for example, getting a wheel alignment after any suspension work including lowering may eliminate the increased tire wear issue. And if a tire is rubbing the sheet panel, it may be possible to roll the edge of the fender or quarter panel enough to eliminate the problem.
How to Lower a Car
Aftermarket kits, using coil overs or airbags, designed for each car model for which they’re offered, are the best way to go. However, they can be very expensive. Many of these lower the vehicle (though that’s not necessarily their main purpose), and well-designed kits that have been properly installed are safe.
At the other extreme are a variety approaches that involve replacing few, if any, of the existing parts. Instead, existing parts, typically springs or torsion bars, are modified.
Here are some common modifications:
Unfortunately, these inexpensive approaches can be damaging to your vehicle or even render it unsafe.
- Shortening or softening coil springs.
- Re-bending leaf springs.
- Changing the spring or torsion bar mounting points.
- Adjusting the torsion bar key (torsion bar suspensions only).
Another important factor to consider is your car’s roll center. Simply put, roll center is the invisible hinge on which the entire dynamics of a car moves about.
Automotive engineers know exactly how much a car’s body will roll in turns, how much suspension travel there is, the center of gravity along the spine of the car, and what the suspension will geometrically do over bumps and different ride heights. We can physically see the control arms, the bushings, the joints by which all of the suspension arms move easily. There is an extra dimension to the complexity of that because the four corners of the car don’t work independently.
There are two roll centers in most cars- the front suspension and the rear suspension. Together, they form what’s called a roll axis; a line drawn through the two roll centers.
The roll center and the instant centers are not fixed virtual points, they’re actually constantly changing when the suspension moves through its stroke, and especially when the body of the car is leaning.
The roll center has a close relationship to the center of gravity. Basically, most suspension engineers try to get the roll center and the center of gravity as close to each other as possible without compromising the physical geometry of the suspension. The engineering battle is getting the center of gravity low enough to meet the roll center once the car is completed so that the suspension arms can be arranged in a natural, level way.
Automotive engineering for street-legal cars is full of compromises. This roll center and center of gravity relationship ends up being one of the big compromises of suspension design. Sometimes, cars have funky geometries and roll centers to compensate for an excessively high center of gravity. This is also a big reason cars like the Subaru BRZ handle extraordinarily well; they have an exceptionally low center of gravity.
Owners, making major changes to the suspension or ride heights of their cars must take their car’s roll center into consideration. Otherwise, they may have a car that handles poorly, or, may even be unsafe.
If the most important thing to you is how your car looks and you don’t care about the ride quality or other associated problems, then you’ll probably love having a lowered vehicle- but bear in mind this might not always be the case. With time you may grow tired of your car’s fidgety ride and the constant scraping as you simply try and drive around day to day. This will eventually start affecting your experience with the vehicle and may result in you selling it sooner.
Alternatively, if you hope to hold onto your vehicle and enjoy it for longer, you should think twice before you lower it. The increased wear and tear that you’ll inflict upon it with lowered suspension will make it a questionable proposition in the long-term.