After nearly thirty years and nearly 300 World Championship titles, Öhlins' revolutionary twin tube shock absorber design remains the number one choice. So what are the secrets behind its success?
While the actual twin tube damper design has been around for a considerable number of years, only Öhlins have managed to successfully master the technology required to make the system work effectively in a variety of damper formats.
Öhlins developed their original Twin Tube (TT) design of damper in 1996 for use in car racing, however it wasn’t long before its success created a demand in many other forms of motorsport.
Today the updated TTX design of damper can be found not only in the very highest levels of four wheeled racing such as Le Mans and World Rally, but also in two wheeled competition on bikes battling in MotoGP and World Superbikes- as well as countless road bikes whose owners have updated their suspension with Öhlins products. When it comes to racing, the vast majority of leading competitors choose Öhlins dampers with their TTX technology as it is a proven winning combination. So what is happening inside the TTX damper?
Unlike a conventional design of damper, the TTX has two separate tubes within the damper's body – a feature that gives rise to its name – as well as a solid main damper piston. The inner tube houses the damper's piston and rod while the outer tube allows the damper's oil to flow between the tubes, via adjustors, and back to the other side of the piston when it is displaced during either the compression or rebound movement of the damper. This flow of oil combined with the adjustors position and solid main piston, eliminates the risk of cavitation, a phenomena that is caused by air bubbles forming in the oil, due to pressure dropping to close to zero somewhere within the damper. Air bubbles in the oil changes its physical properties significantly. In a TTX damper the lowest pressure within the damper remains well above zero throughout the piston's movement, eliminating the risk of cavitation regardless of setting. While this initially sounds complicated, it is actually a very simple, and elegant, solution to creating accurate, consistent damping qualities.
When a conventional damper is under its compression or rebound stroke, the oil is pushed through the main piston which has several holes in it covered by shim stacks to control the main flow of oil. This gives the damper its main resistance to movement, however fine tuning is done via needle adjustors which regulate some of the oil’s flow. A conventional damper can be set up wrongly so that cavitation can occur as opposed to the TTX. Needle adjustors and the shims rely on constant properties of the oil to allow them to accurately control the damping, something that doesn’t happen when the oil is full of bubbles.
When a TTX design of damper is displaced, the oil is pushed by the solid main piston through two damping needle adjustors with shim stacks and check valves, similar in design to those in a conventional damper.
When the oil flows under compression it is channeled through a needle adjustor and shim stack on the compression adjustor and a check valve that bypasses the rebound adjustor. Once the oil passes the adjustors it flows between the tubes that make up the damper’s body and back to the rebound side of the solid main piston.
During the rebound stroke the oil flows back along the same path on as when it was under compression but in the opposite direction. When the oil reaches the rebound adjustor the needle restricts its flow together with the shim stack to create adjustment. A check valve in the compression adjuster lets the oil back to the compression side of the solid main piston.
This layout of the TTX means that the damper's adjustors are more separated in compression and rebound, and also, shim settings can be changed much more quickly for the ability to fine-tune the suspension's movement – leading to a better set up suspension system and therefore a better handling vehicle.
So simple, and yet effective, is Öhlins TTX design that the company has been able to expand its use from not only car dampers but also motorcycle shock absorbers and even motorcycle forks – an application for which it has proved extremely effective at both world and domestic racing.
So now you know the secrets behind the TTX system, why not try it out for yourself? It is not only the world's best racers that use TTX technology inside, it is out there for everyone to own…