The Stabiliser – an underrated component

The stabiliser bar is a component of the suspension and connects the wheel suspension of an axle with the body structure. Many cars are equipped with a stabiliser bar on the front axle and some of them with one on the rear axle as well. Stabiliser bars have been installed in passenger cars for many decades and have remained practically unchanged in this time. The stabiliser bar (or anti-roll bar) is little known to many motorists, although this component plays a major role in ensuring a safe and comfortable journey. The simple reason: Without a stabiliser bar, vehicles would overturn in corners and driving comfort would be drastically reduced when driving straight ahead as well. As a rule, even knocking noises from the suspension are attributable to a fault in the stabiliser bar area. Failure of or damage to the stabiliser bar is mostly inexpensive. This is due to the relatively low material costs and straightforward installation. But beware: If the stabiliser bar is damaged, the vehicle should not be moved. Failure increases the risk of the rolling motion of the body structure getting out of control and the vehicle overturning.

Design and Function

The stabiliser system also consists of other components, e.g. stabiliser links and stabiliser bearings. The stabiliser bar is mostly mounted on a subframe and in rubber bearings. The stabiliser links connect the stabiliser bar to the suspension struts or, alternatively, to the control arms. Special ball joints on the stabiliser links ensure the necessary freedom of movement to allow the stabiliser bar to do its job flawlessly. When a wheel deflects, the torsion of the stabiliser bar ensures that the other wheel is also raised and likewise lowered upon rebound. This prevents excessive rolling (lateral tilting) of the body when cornering. If the two wheels deflect simultaneously, the stabiliser bar does not activate.

Failure Symptoms

In the event of failure or damage to the system, loud knocking noises frequently occur in the suspension when driving over bumps or potholes. These are mostly caused by worn bushes or defective ball joints on the stabiliser links. In the case of worn bushes, an unintended play arises between the bush and stabiliser bar, and the stabiliser bar begins to rattle in the bushes on deflection and rebound. A frequently installed type of stabiliser link features ball joints that are protected by a rubber boot from spray water and external influences. They are also packed with grease to make movement as frictionless as possible. Every now and then, the rubber boot or the associated seal is damaged. This allows water to enter and provides for unnaturally high wear. The consequence: too much play in the joint, which leads to the aforementioned noises. When replacing the stabiliser link, it must always be ensured that the correct torque is applied during installation. Otherwise the ball joint can be damaged, wear prematurely or even break off.

Used with permission by febi-bilstein.

From Febi Bilstein – Underestimated, but Important: The Anti Roll Bar

Anti Roll Bar

The anti roll bar is a component of the chassis and connects the wheel suspension of an axle with the body structure. Many cars have an anti roll bar on the front axle, some of them also have them on the rear axle.

Anti roll bars have been used in passenger cars for decades and have been a virtually unchanged component ever since. Many motorists are unaware of the anti roll bar, although the replacement part makes an important contribution to safety and comfortable driving. The simple reason: without the anti roll bar, vehicles would tip over in a curve and driving straight ahead would be extremely uncomfortable. As a rule, even the rumbling noises from the chassis can be attributed to a defect in the area of the anti roll bar.

A failure of or damage to the anti roll bar is usually not expensive. This is attributable to the relatively low material costs and simple installation. But beware: if the anti roll bar is damaged, the vehicle should no longer be driven. The failure increases the risk that the rolling movements of the superstructure get out of control and the vehicle overturns.

Design and Function of the Anti Roll Bar

The anti roll bar includes other system components, e.g. coupling rod and anti roll bar bush. The anti roll bar is usually fitted to a subframe and mounted in rubber bearings. Double rods connect the anti roll bar to the suspension struts or alternatively to the control arms. Special ball joints on the coupling rods provide the necessary freedom of movement so the anti roll bar can perform its work flawlessly.

When one wheel is deflected, the torsion of the anti roll bar ensures that the other wheel is also raised and lowered when it is lowered. This prevents the body from swaying excessively (tilting sideways) when cornering. If both wheels enter simultaneously, the anti roll bar does not take action.

Symptoms of Failure

If the system fails or is damaged, strong rumbling noises often occur in the chassis when driving over bumps or potholes. In most cases, these are due to worn out bearings or defective ball joints of the coupling rods. If the bearings are worn out, there may be an unexpected play between the bearing and the anti roll bar. The anti roll bar may begin to rattle in the bearings during compression and deflection.

A very common type of coupling rod is equipped with ball joints which are protected against spray and external factors through a rubber boot. Furthermore, they contain a grease filling in order to allow for a smooth movement. From time to time, the rubber boots or the associated seals are damaged. As a result, water can penetrate and cause an unnaturally high level of wear.

The result: too much play in the joint leads to the sounds described above. The correct torque must be observed when mounting the coupling rod. Otherwise, the ball joint may be damaged and may wear out prematurely or even break off.

Article By Mary VerDuin
Dated April 29, 2020
Source: https://blog.febi.com/en/underestimated-but-important-the-anti-roll-bar/
Used with permission by Febi Bilstein

Chassis Mounts: For More Comfort and Better Control

Axle Beam Mount

Axle Beam Mounting

The design of vehicles is constantly evolving. The desire for non-intrusive suspension systems that do not impact the interior of the vehicle has made it necessary to use a suspension sub-frame. These sub-frames are made of tubular steel or aluminum tubes and are mounted to the vehicle body with rubber-metal bushes.

Strut Top Mounts

The suspension strut mounting consists of a composite rubber bush mounted on the top of the damper and connected to the vehicle’s chassis. It is an integral part of the suspension strut assembly. Strut mountings can also be equipped with a bearing or bearing plate, which allows the strut to rotate with the steered wheels.

Control Arm Bush/Hydro Bushing

The elastomeric materials used in the production of rubber-metal parts are matched precisely to the technical requirements and loads of their specific fitting position. Despite all of this, passive rubber-metal components cannot absorb all of the vibrations within the chassis. As a result, hydraulically dampening elastomeric bearing – “Hydromounts” – were developed, which enable the isolating and dampening of vibrations.

Anti-Roll Bar Bushes

Anti-Roll Bar Bushes

The anti-roll bar is mounted onto the vehicle’s sub-frame or chassis by means of two bushes. The positive connection of the bonded rubber bushes prevents relative movements between the anti-roll bar and the bonded rubber bush. The rotational movements of the anti-roll bar are absorbed in the mounting while the vehicle is being driven on a variety of road surfaces. This achieves a high degree of efficiency to reduce NVH (Noise, Vibrations, and Harshness) and increases driver comfort.

Chassis mounts – like the strut support bearing – should have good elastomeric properties

Article By Mary VerDuin
Dated February 28, 2020
Source: https://blog.febi.com/en/chassis-mounts-for-more-comfort-and-better-control/
Used with permission by Febi Bilstein