The Difference Between Mono-Tube and Twin-Tube Shocks
In the automotive world, shock absorbers are a big part of how your vehicle handles and finds grip. That’s why it’s important to understand the differences between mono-tube and twin tube shocks.
Shock absorbers work by mixing a mixture of hydraulic fluid and pressurized gas to dampen the force of impact. The most common shock absorber design is the mono-tube shock.
Improved Ride Quality
TWIN TUBE SHOCKS
The twin tube shock design is the standard and most common on passenger cars and light trucks. They are inexpensive, and provide satisfactory safety, handling, and control for most driving conditions.
These shocks are easy to replace, and are available at a variety of car dealerships, auto parts stores, and repair facilities. There are also single and dual adjustable models, allowing for different compression and rebound settings on the fly.
A number of shock manufacturers offer reservoir shocks, remote (connected with a hose) or piggyback (directly on the main shock body, usually connected by some form of hardware), which increase monotube shocks’ capabilities significantly. They can be adjusted by external knobs or twisting mechanisms, allowing for more precise tuning than most single or dual-adjustable shocks.
They are also often less expensive to manufacture than monotube shocks. The outer tube serves as a fluid reservoir, and a gas charge is placed in the top to prevent foaming of the hydraulic fluid. This eliminates oil and gas mixing (foaming) that can negatively impact ride quality.
This technology was originally developed for racing in the 1960s and 1970s. Since then, it has become an OE shock on a large range of cars, including Mercedes, Audi, Porsche, BMW, Saab and Volvo, 1993 and newer Camaro and Firebird, late-model Corvettes, and many pickup trucks.
These shocks are also much easier to install than their twin-tube counterparts. Compared to the inverted type, even slight misalignments can throw off your shocks’ damping performance.
Less Foaming
The most common type of shock absorber found in most vehicles is a twin tube design. It consists of an inner tube (piston chamber) that is pressurized with oil and is surrounded by an outer tube (reservoir) that is filled with gas. As the piston moves, the TWIN TUBE SHOCKS fluid inside flows back and forth between the two tubes via valving to provide damping.
However, as the fluid moves through the valve or valves, it can generate a cavitation effect which produces pockets of air in the fluid. This aeration can result in foaming of the fluid and reduced ride control.
Some shocks reduce the aeration that occurs by injecting a charge of pressurized gas into the hydraulic fluid to minimize foaming. Ideally, the gas and oil should be separated by a floating piston to minimize mixing and eliminate aeration.
Another method of reducing the aeration is to use an internal bypass. Shocks that employ this method use cutouts in the internal tube so that a certain amount of the fluid can go around the main piston and circulate to the other side of the valve. This allows the main piston to travel through the oil a shorter distance and creates less resistance.
In addition to the internal bypass, some shocks also have a gas pressure control system that limits the gas flow to prevent aeration. This allows for more consistent shock performance by preventing the gas from being overly compressed or creating bubbles that would weaken the shock.
Typically, aeration in shocks can be controlled by injecting nitrogen into the hydraulic fluid, though this requires the gas and hydraulic fluid to be separated to ensure that they don’t mix. Foaming can also occur if aeration is not prevented, and it can lead to a loss of ride control as the shock absorber deteriorates.
Monotube shocks are more prone to aeration than twin tube shocks, but they have some advantages over the latter, including a higher gas pressure and better heat dissipation. The gas pressure in a monotube shock is typically 360 psi, but it can be as high as 260 psi depending on the manufacturer.
More Responsive
One of the most important things to consider when buying new shocks is how responsive they will be. Ideally, your shocks should react to changing road conditions and allow you to adjust your ride comfort as you drive.
Monotube and twin tube shock absorbers both provide damping and control for your truck. However, there are some key differences between these two types of shocks that will help you choose which type is best for your truck.
First, monotube shocks have a floating piston that separates the gas chamber from the oil chamber, so there is no mixing of the gas and fluid. This makes them much more responsive to your driving needs, giving you additional control and damping on demand.
Depending on the manufacturer, some monotube shocks also feature reservoirs to increase their capacity and improve heat dissipation. These reservoirs can be connected remotely (through a hose) or piggyback directly to the main shock body, usually through some form of hardware.
This design also provides a higher piston stroke to damper body ratio, allowing the shock to move more in less space. This increases the longevity of the shock as well as makes it more durable against road debris.
Some of these reservoirs include a foam sleeve or gas bag that contracts and expands with respect to shaft displacement to eliminate air pockets, increasing the performance of your shock absorber.
Another benefit of monotube shocks is that they can be installed upside down or right-side up without compromising their function. The design allows for easier maintenance and performance changes than their twin-tube counterparts.
Many people also prefer the way monotube shocks work, which helps to keep costs down. They can be adjusted through external knobs and twisting mechanisms, and there are even race-level shocks that allow you to adjust compression on the fly.
In addition, monotube shocks are easier to install than twin-tube designs. They also come with a longer warranty period. This is because they are less likely to experience aeration, which is the mixing of the hydraulic fluid with air bubbles. Aeration is a common problem with shocks, and it can lead to fading of the damping forces in your shock.
Less Expensive
TWIN TUBE SHOCKS are more affordable than monotube shocks, and they also provide excellent handling characteristics for most “everyday” driving conditions. They are the most commonly used shock absorbers on streetcars, light trucks, and SUVs.
Twin-tube shocks use a single piston valve to control both the pressure and flow of hydraulic fluid in each chamber. The piston is located inside the outer tube and acts as a barrier to separate the oil and gas chambers. This design prevents leakage and ensures a long service life.
They do however have one major disadvantage, which is that they are more prone to foaming than monotube shocks. This happens because the oil and gas have a tendency to mix. This can cause the shock to fail in certain situations or even cause a significant drop in ride quality.
Fortunately, many manufacturers have come up with ways to minimize the risk of this happening. For example, some use nitrogen, an inert gas that is less prone to foaming and can assist in the dampening of sudden or forceful jolts.
Another advantage of monotube shocks is that they are easier to maintain. TWIN TUBE SHOCKS A simple valve adjustment can make a big difference in the performance of these shocks.
This is also an important factor in off-roading and racing where constant pressure on the shock may lead to fading, which can affect the damping of the shock and cause handling issues or changes.
The best way to decide if a monotube or twin-tube shock will suit your needs is to speak to an expert in the suspension industry. They can help you customize your hardware selection and setup process so that you get the most out of your shocks.
If you are looking for a budget-friendly replacement shock for your daily driver, look no further than the KYB Excel-G series of shocks. These shocks are valved 10% stiffer than your original equipment units to make up for wear in your vehicle’s suspension and return it to factory performance.
The high-quality Excel-G series is designed with a low-pressure twin-tube design for years of comfortable driving and slightly improved handling. Typically, they have a three-year warranty and a brushed aluminum body that resists rusting for longer service life.
