Last Updated on: 7th September 2023, 12:38 am
You’ve been looking at the various options for suspension upgrades. Are you wanting to lower your car or improve handling?
But you also want to know the differences, benefits and drawbacks of coilovers and lowering springs.
Read this article for the most in-depth guide to coilovers vs lowering springs.
What Is a Coilover?
Coilovers are found on many vehicles, from RC cars to ordinary passenger cars, from racing cars to offroad cars.
Sometimes, they are used as a factory suspension option on new cars.
Coilovers are used in double-wishbone suspension systems and are often an element of MacPherson struts.
There are two types of coilovers:
- Full coilovers
- Slip-on coilovers
Full coilovers are matched with a shock absorber (damper) from the factory, but with the slip-on coilovers, the dampers and springs need to be bought separately and then assembled.
Many companies manufacture aftermarket coilovers for vehicles, many of which allow the customer to adjust various vehicle settings such as ride height, spring stiffness and damping.
Other settings can also be adjusted, such as camber and caster angles, providing that the car’s suspension allows it and if the coilovers are supplied with adjustable top mounts.
This high degree of adjustment is what gives coilovers an advantage over standard MacPherson struts.
Coilovers can allow you to lower your car and therefore lower the vehicle’s centre of gravity, this increase the car’s roll stiffness and reduces weight transfer when changing direction.
What Is a lowering Spring?
Simply put, lowering springs are designed to lower your car by using slightly smaller springs with a somewhat higher spring rate to compensate for the lower ride height.
The smaller the lowering spring is, the closer to the ground the car will be. Similarly to coilovers, lowering springs will lower the vehicles centre of gravity, improving handling.
They will increase the cars roll stiffness and reduce weight transfer when changing direction.
A lowering spring will replace only the spring in the suspension setup.
Advantages & Disadvantages of Coilovers
While performance and handling advocates rant about the advantages of coilovers, most people with coilovers will notice two clear benefits.
You can achieve similar results by installing lowering springs if you’re on a tighter budget instead of installing coilovers, but there are advantages and disadvantages to each setup.
A coilover setup is usually designed for ‘fast road’ and track use more than daily driving use.
If you’re setting up your car for performance or want the lowered look, coilovers are a great choice of suspension upgrade.
However, coilovers have one major disadvantage. They are usually much more expensive than lowering springs.
Advantages of coilovers:
- Easily adjustable
- Better handling
- Have unique features
Read below for a more in-depth explanation of each advantage.
1. Easily Adjustable
An adjustable coilover has many different adjustability settings, such as adjustable ride height, spring pre-load and compression, damper adjustability and more.
Adjustable coilovers can be fine-tuned and adjusted quickly and easily, meaning you can cater for different usage and scenarios.
It’s one of the most significant advantages of a coilover setup.
Whether you want to raise your vehicle for that long trip or have it ultra-low while it’s at a car show, adjustable coilovers let you make that happen easily and quickly.
2. Better Handling
While coilovers are better known for their adjustability, they’re assumed to have a worse ride comfort.
If you install coilovers correctly and set them up properly, you’ll get much better handling.
And depending on how you have set them up, they can often ride better than stock suspension.
Coilovers will allow your vehicle to take those sharp turns better and faster.
If you’re after straight performance and adjustability, then coilovers are a great option.
3. Unique Features
Some higher-end coilovers also offer other unique features not seen with lowering springs or stock suspension setups, such as the following.
- External reservoirs
- Inverted dampers
- Multiple springs and spring rates
- Poly-bushed mounts and components
- Nitrogen charged dampers
- Exotic fluids and oils
Advantages & Disadvantages of Lowering Springs
One key advantage to a lowering spring over coilovers is its price. Lowering springs are usually much less expensive than coilovers.
However, lowering springs only change one part of a suspension setup – the springs.
The dampers remain unchanged; combining lowering springs with dampers not matched with the springs can result in different and possibly unfavourable handling characteristics.
The other disadvantages compared with coilovers is they are non-adjustable.
This means lowering springs are a set height and cannot be changed unless they’re replaced.
You also can’t adjust anything else, such as damping, compression etc.
Besides these disadvantages, lowering springs will lower the car and reduce the centre of gravity, therefore improving cornering and handling in this regard.
Types of Coilovers
There are two main types of coilovers:
- Full coilovers
- Slip-on coilovers
There are also two main types of shock absorbers:
- Mono-tube
- Twin-tube
A monotube shock absorber can also be mounted upside down, known as an inverted damper, which has several unique advantages.
There are slightly different setups such as multiple springs and progressive spring rate coilovers, you can read more about these further down in the lowering spring section.
Full coilovers are matched with a shock absorber (damper) from the factory, but with the slip-on coilovers, the dampers and springs need to be bought separately and then assembled.
Other than that most coilovers are very similar in design and differ in only a few aspects, such as the type of shock absorbers, spring design and spring rates, rebound and compression rates and some other minor features.
Mono-Tube Shock Absorbers
Monotube dampers were an innovation from the 1950s.
They are larger than a twin-tube setup because they place the oil reservoir and the high-pressure gas charge in line inside a single shell.
A ‘floating‘ piston separates the liquid and the gas from each other. The main piston in the damper pushes through the oil like normal.
Instead of pushing oil into a separate chamber, the oil passes through valves in the piston. This system allows the gas to become part of the spring action.
It compresses gently over minor bumps and more quickly through more significant bumps; this can theoretically improve control and response.
Meanwhile, the oil reservoir is sealed and can’t foam, although it can still experience cavitation.
Another advantage of monotube dampers is they can be used either way up, unlike most twin-tube dampers.
Coilovers can be either twin-tube or monotube, but most common fitments need to be shorter and therefore adopt a twin-tube damper system.
Twin-Tube Shock Absorbers
This older style of damper is easier to produce and more popular because of that, but neither of these things means it’s not a practical design.
The basics of how a twin-tube damper is built involve two tubes, one within the other. The inner tube contains the main oil reservoir, which a piston travels within.
When the suspension is compressed, this piston forces oil out of the inner tube and into the reserve tube.
When the piston moves back, the opposite happens, and oil is drawn from the reserve tube back to the inner tube.
Twin-tube dampers have been manifested and upgraded in various ways over time.
Arguably the most significant upgrade is gas charging.
Either air or nitrogen (nitrogen is more expensive but better) is inserted at low pressure into the outer tube, far enough above the valve that it can’t escape into the inner tube accidentally.
Its purpose is to maintain pressure on that end of the oil volume, minimising the aeration or foaming that can occur in a twin-tube damper system under harsh use.
Some manufacturers also have a way of incorporating small-bump sensitivity to twin-tube dampers while still maintaining large-bump capability.
This involves placing minor grooves in the upper and lower sections of the inner tube’s wall, where the piston moves.
These minor grooves effectively slow the piston down and help prevent a bottom-out or top-out situation while leaving the central portion of the damper free to move quickly and easily over smaller bumps.
Inverted Monotube Damper
An inverted monotube damper has several advantages compared to a transitional damper unit.
The benefits of an inverted damper are as follows:
- Reduced flex and improved strength
- Reduced unsprung weight
- Reduced heat transfer
Reduced Flex & Improved Strength
Inverted dampers have the side effect of improved suspension geometry, reducing unwanted suspension flex.
They are also stronger by design and more resilient to high impact bumps in imperfect road surfaces.
Reduced Unsprung Weight
Unsprung weight is reduced by relocating the oil and gas reservoir away from the wheel hub and attaching it to the shell of the car.
Unsprung weight is vital to a cars performance, a lighter wheel and hub assembly which readily moves in response to road bumps will have more grip when tracking over an imperfect road surface.
High unsprung weight can lead to ‘wheel hop’ over a bumpy surface and will reduce the quality of the ride.
This high unsprung weight will also worsen handling as it impairs the suspensions ability to maintain contact between the road and the tyre.
> Read more about sprung vs unsprung weight
Reduced Heat Transfer
A car will generate a lot of heat within its braking system, especially if it’s driven hard.
This heat can be conducted through the hub and into to the damper unit, by inverting the oil and gas reservoir the oil and gas is moved away from the hub assembly.
This inverted damper system will reduce the amount of conducted heat being transferred from the braking system to the gas and oil in the damper unit.
As the oil and gas in the damper is heated, its properties change, this heat transfer has an effect on the damping characteristics of the suspension.
By keeping the gas and oil temperatures down, the dampers maintain more consistent damping rates resulting in a better performing suspension.
Types of Lowering Springs
There are multiple types of lowering springs, which can sometimes also be incorporated into coilover setups.
The following are some of the most common types of lowering springs:
- Linear
- Pigtail
- Conical
- Miniblock
There are also a few different types of spring rates, such as:
- Linear
- Progressive
- Dual Rate
These different types of springs and spring rates are also used on coilover setups.
They provide different types of spring rates and have their own advantages and disadvantages.
Linear Springs
Linear rate springs have one defined spring rate per inch of deflection throughout most of their range of deflection, meaning their spring rate does not change based on compression.
For instance, a 300lb/in linear rate spring will take approximately 300lbs to deflect it 1 inch.
The next 1 inch of deflection will take another 300lbs of load and the next 1 inch of deflection will take an additional 300lbs of load, this is the same until the spring becomes solid.
Progressive Springs
Progressive rate springs are generally classified into two sub-types of springs; constantly increasing rate springs and dual-rate springs with two linear rates connected with a rate-transition range into one spring.
However we will classify them separately for simplicity.
The first type (constantly increasing rate) of springs are most often used as “load-compensating springs” on the rear of a vehicle when the vehicle will often see significant load changes in the cargo area.
These are most often stock replacement type suspension springs.
These types of springs are identified most easily by their continually varied spacing between the coils.
Dual-Rate Springs
The second type of progressive rate suspension spring is the dual-rate spring with two linear rates connected with a rate transition range, this is a much more complex suspension spring.
This type of spring is used primarily in vehicle racing and high performance applications.
These type of springs are easily identified by having a few closely wound coils at one end of the spring and then wider, equal-spaced coils at the other end.
They have rates described differently, for example; 200/425lb/in, this means that the spring has an initial rate of 225lb/in through some range of its deflection and then the rate transitions to 425lb/in through a deflection range usually of around 1”-1.5″.
The big advantage of these springs is that they can provide roll control in addition to roll control provided by sway bars (anti-roll bars).
Coilovers vs Lowering Springs
If you have the budget, adjustable coilovers are a great alternative to a lowering spring setup as they will allow you to adjust your ride height and other settings.
Unlike lowering springs, you are not stuck to one specific ride height and stiffness.
With a good set of coilovers you do not have to sacrifice ride quality to go low and improve handling.
Lowering springs are a good option if you are on a budget and need a quick and inexpensive way to lower your vehicle.
But if you’re after a suspension setup with high performance in mind then coilovers are a good idea.
Coilovers have several advantages over lowering springs:
- Fully adjustable (ride height, stiffness/pre-load, on higher-end models; compression, rebound, camber)
- Multiple damper designs (twin-tube, mono-tube, inverted mono-tube)
- Unique features (external reservoirs, nitrogen charged etc)
- Easy and quick adjustability
- Stronger and more durable
- Much improved handling
My final verdict is that coilovers are a better option if the budget allows.
Upgrading to coilovers pairs well with installing uprated sway bars.
