When your car was designed, the engineers responsible worked to strike a balance between the two main principles of suspension; ride and comfort. The setup will have been chosen with general use in mind. However not everyone uses their car in the same way, and even if they do, they don't all drive on the same types of roads. As such, modifying a car's suspension can make a massive difference to its performance and general driving characteristics. There is a myriad of different offerings available when it comes to aftermarket suspension components, from setups that mirror the original design, through to extreme options on either end of the ride vs handling spectrum. Here we will go over a few of the things to consider when making any changes to your suspension, as well as the most commonly used tools, and a few things that most definitely, under any circumstances, should NOT be done.
Before attempting any modifications to your vehicle, check with your local state laws, your insurance and a professional to ensure you don't waste your time and you understand the costs and changes.
What type of suspension should I buy?
If you aren't happy with how your car feels when you are driving it, try to think about where it might currently sit on the scale between ride and handling - Is it comfortable, but a little too floaty? Does it handle well, but you feel every single bump? Also, think about how the car sits on the road - Is it too low and so scrapes on the driveway? Or does it resemble the lunar explorer somewhat? There are a few main factors to consider any given suspension component, from how it will alter the car's ride height, to how it might impact your comfort and the car's handling. With this in mind, let's look at a few of the most common aftermarket options in suspension.
Lowering your carProbably the most commonly modified area of a car's suspension is the springs. We have all seen a great looking car, that has fantastic wheels, a beautiful paint job, and a souped-up engine, but that seems to be sitting so high, that it looks like it might be allergic to tarmac. The usual solution is to fit lowering springs, but merely changing the springs isn't necessarily the best option, given that there are a few other parts that work with the springs to make sure that they do the best job that they can. That isn't to say that aftermarket springs can't be used with factory shocks, sway-bars and linkages, but rather that they have their place in more mild setups, where lowering the car isn't going to put any undue stress on the other components. Some offerings are perfectly adequate for dropping the ride height of the car by a few inches, and will not only transform the look of the car for the better but due to their unique construction, may account for the shortened travel, by being stiffer or more springy. The next step may be to incorporate shortened shocks into the setup - these will have less travel, but often have more dampening ability, and therefore will tighten up the handling characteristics, at the expense of comfort - As mentioned above, this will move the car further along the spectrum, from ride towards handling.
If you want to switch out the springs and shocks together, another alternative is to use coil-overs. These are specially designed to provide an all-in-one solution to both your ride height and the stiffness of your suspension setup, with many of the better offerings having built-in adjustability that will allow you to fine-tune your car's height, dampening and various other properties - dependant upon what type you choose.
It is essential to bear in mind that whenever you make a change to one component, you inevitably introduce a change into the way that the whole system works together. For this reason, it is always a good idea to seek advice around what the trickle-down effects on your whole suspension setup might be and look at upgrading anything else that might need to work harder to offer you the desired handling and ride characteristics. It is recommended to do local law research, or seek advice around what is best for your desired use.
Raising your suspension
If you have ever driven your 4x4 off-road, you may have noticed that most factory setups aren't engineered to offer much in the way of ground clearance. Fortunately, there is a solution to the potential problem of dented sumps and a damaged undercarriage - lift-kits and longer shocks. Most decent 4x4 setups will involve raising the body of the vehicle up and away from potentially damaging rocks, stumps and ridges. They will do this by increasing the suspension travel as well as lifting the body off the chassis. In order to do the former, longer shocks and springs are used. These can be fitted along with upgraded bushings, linkages and sway-bars to pump up the off-road capabilities of even the best factory 4x4. You don't necessarily need to change over every component, but as with lowering a car, it is always best to consider how each change you make will impact the whole suspension system, and as such, it is recommended to do local law research, or seek advice around what is best for your desired use.
One type of shock absorber commonly found in the more aggressive 4x4 setups is the gas-shock. These shocks have a pocket of gas inside them, that is compressed along with the hydraulic fluid, to offer a stiffer but more responsive ride. There are a few different options available, some of which use proprietary technology such as special foam or nitrogen gas, all of which offer different levels of dampening and absorption, and as with everything suspension, remember the ride/handling spectrum - 4x4s are no exception to the rule!
Replacing bushings - Rubber or polyurethane?
One of the suspension components that is most frequently forgotten, but most frequently in need of replacement, is the humble bushing. Since the bushing's job is to isolate the other parts of the suspension setup under your car, there are quite a few of them. They are designed to facilitate movement in the various bits and pieces but to make sure that none of the friction, noise and vibration makes its way to you. Because of this, the bushings in your suspension setup will experience an awful lot of wear over the lifetime of your car, and it is vital that they be checked periodically to ensure that the material that they are made from isn't cracked, perishing or outright missing! Speaking of the material that they're made from, most bushings are moulded from rubber, but there are a few different aftermarket options - the vast majority of which are made from polyurethane plastic of varying degrees of hardness. The harder the bushings, the less the suspension parts can move in ways that they aren't meant to, and the better your car will usually handle. But if we remember the scale, improving the handling always comes at a cost to - you guessed it - the ride, and therefore your comfort! Upgrading the bushings is a good idea (even if your ride may be a smidge firmer) as rubber is vulnerable to deterioration through exposure to oil and other petrochemicals, as well as extreme temperature (like the Aussie summer perhaps!) and any time bushings are replaced ALWAYS replace them on both sides of the car.
What tools will I need?
When replacing parts, or modifying your suspension setup you can get by with a basic selection of tools. However, there are a few situations that you may run into, where that basic toolset just won't cut it. Below is a selection of the tools and equipment commonly used when working on your suspension.
Socket set - Your standard socket set should be the backbone of any toolbox when working on a car. It will find use on almost every part of a vehicle, and your suspension is no exception. From the nuts that hold a Macpherson strut's top hat to the body of your car, to the bolts that run through the eyelets on a sway-bar end, you will find that your standard socket set is the best way to get this stuff off and back on again. You will likely need to pick up a selection of larger sockets, or at the very least, one that fits the central wheel hub bolt, should you need to remove it to gain access to any suspension components.
Spanners - As with a socket set, you should have a decent set of spanners. Most European and Japanese cars will use metric sized fasteners, whereas American cars often use Imperial sizes. It is a good idea to have a set that contains both just in case. There are a lot of different types of spanners, though to begin with, standard open-ended types can be used in almost all instances. Ratcheting types can also be purchased, and these can make your job a lot easier - especially in places where you don't have a lot of space or visibility.
Breaker bar - Sometimes nuts and bolts are just stubborn (or if you are like me and skipped arm day a few too many times, you just pretend that they are.) Therefore it is a great idea to add something to your arsenal that can lend you a bit more leverage (and costs a lot less than a gym membership) which is the breaker bar. It will allow you to crack tougher nuts and bolts, and will save you frustration and time in doing so.
Impact wrench - Another great tool for removing stuck fasteners is the impact wrench (or rattle gun). These can be pneumatic or electric (battery powered or plug-in) and will make removing stubborn nuts and bolts a breeze - especially where there might not be enough room to maneuver a breaker bar. Remember that although they will fit, you shouldn't use standard sockets with an impact wrench as they aren't designed to handle the stresses involved - Instead, you can purchase specially forged sockets for use with the wrench.
Ball-joint separator - Many suspension components are attached using movable ball-joints, and in order to separate them, a special tool is required. They are fairly inexpensive and are an invaluable addition to your kit. There are a few different types, from simple chisel-like designs to more complex affairs that use a threaded pusher. Anyone will do the job, but each offers differing levels of cost and simplicity and ease of use.
Gloves, goggles, and consumables - Whenever you are working under a car, you are going to spend a great deal of time looking upwards. Hence you should ALWAYS wear safety goggles to prevent any grime, oil or other mystery substances from falling into your eyes and causing painful and potentially permanent injury. That same stuff will likely wind up staining your skin and dirtying your clothes, so shop gloves and protective clothing are also highly recommended.
WD40 or CRC - Another often overlooked thing to have handy is some penetrating spray or lubricant. Most of the time, a stuck bolt can be sprayed with special penetrant and left for a wee while then simply undone once the spray has worked its magic. Also be sure to replace any split-pins with new ones, as well as apply new grease where required, and replace anything you see that is worn out. There is nothing worse than having to get back under a car that you've recently finished working on because you skimped on a couple of bucks and something else broke!
Modifying suspension - what not to do!
There are a few things that should NEVER be done when modifying the suspension, most of which are common sense and apply to anything you do when working on a car - such as not securing your vehicle on jack stands when working underneath it, or not replacing worn or damaged parts. Other things are specific to suspension:
Cutting Coil Springs
The most common no-no that is seen, but should never be done is to cut springs in order to lower a car. This is a terrible idea for a few reasons, the first being the impact on suspension travel. Springs are manufactured to flex progressively, and by cutting a portion of the spring off, you limit the ability for the suspension to support the weight of the car. The energy generated when the wheel travels up and down, which means that the vehicle may scrape, bottom out or wallow, or alternatively may become bouncy and erratic, dependent upon what parts of the spring are cut away. The other significant effect that cutting springs will have is to reduce the spring's ability to remain in place upon full extension of the suspension setup. Springs are seated in such a way as to remain in place when the suspension is fully extended, however cutting the springs too short may mean that they move around or even fall out of place. This is incredibly dangerous, not just to the occupants of the car, but to anyone around it!
Slammed Suspension or Lifted Suspension
Care should be taken to ensure that the suspension in your car is selected to work in unison. If you raise or lower your vehicle dramatically, then it should be done so with a mind towards ensuring that each component can still do its job unimpeded. Not only this, but you must make sure that your car isn't going to become unstable and therefore dangerous. Raising a vehicle also raises its centre of gravity - increasing the chances of it rolling over when cornering or leaning. Lowering a vehicle reduces the clearance beneath it - potentially resulting in damage to the exhaust, the sump and the driveline. No matter what changes you make to your suspension, always ensure that you have not adversely affected the steering geometry and the ability for the wheels to turn.
Are Lowering Blocks Legal?On many older cars (and the rear end of even modern utes, vans and other commercial vehicles) leaf spring setups are very common. In order to lower the ride-height of cars with leaf springs, the springs themselves can be kept as they are, and instead simple blocks of metal can be bolted in to lower the car - called, surprisingly, lowering-blocks. There are a few different types, but the vast majority sit between the springs and the axle of the car, effectively pushing the axle upward in relation to the spring mounting point, and therefore allowing the body and chassis to sit lower to the ground. They are fastened in place with special lengths of metal called u-bolts that are positioned over the axle housing and have threaded ends that go through locating holes in the block, and are fastened with a retaining plate, washers, and nuts to secure it all. In most parts of Australia the use of these blocks is illegal, and in New Zealand they must meet very specific requirements - however, it is always a better idea to fit proper leaf springs that are designed to lower your car instead. If you do wish to use lowering blocks, be sure to check with your state or country laws and regulations - the last thing you need on top of a potentially unsafe vehicle, is added legal trouble!
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