The effects of defective steering and suspension components on the steering of the vehicle and thus the safety of its passengers are enormous. Particularly with modern chassis designs, it is important that the interaction of all relevant components are a 100 percent functional. In addition to the main suspension gear components, small elements such as rubber-to-metal parts should also be checked and replaced regularly.
Within the chassis system rubber-to-metal parts (RTM) absorb unwanted vibrations and noise. They act as the elastic connection between the individual chassis components. Additionally, these parts have an influence on noise generation and transmission, steering behavior and driving stability. This is especially true for road bumps, braking and evasive maneuvers. The specific dimensioning and shaping of the RTM has an influence on the chassis tuning: It improves steering behavior and driving stability supported by suspension strut support bearings, subframe bearings, control arm bearings, stabilizer bar bearings or axle beam bearings. Depending on the make and model up to twelve different RTM can be installed within the chassis system.
Other crucial parts - in addition to conventional rubber bearings - are hydraulically damped bearings namely axle housing, axle beam and control arm bearings. Due to the damping properties of the fluid in addition to the rubber core, the so-called hydromounts achieve optimum vibration reduction in higher frequency ranges.
Although RTM are not amongst the classic wear parts, their complex tasks mean that they are subject to high dynamic loads and harmful environmental influences such as heat or road salt. These factors can lead to heavy wear and tear. Damaged RTM in the chassis not only impair safety and comfort, they can also have a negative impact on adjacent chassis components. If a defect is detected, the affected parts need to be replaced immediately – ideally in pairs for maximum safety.
Installation and removal of rubber-to-metal parts
The installation and removal of these components requires suitable tools, sometimes also special tools. Prior to dismounting, it is essential to pay attention to the position of the bearing in order to identify any installation-relevant positions – an important information later during mounting. ZF Aftermarket experts generally recommend marking the installation position in advance. In some cases, positioning marks on the parts themselves and/or at the mounting position allow a precise fitting of the new bearing. Oil as an assembly aid should not be used for RTM, as it corrodes the rubber and thus damages it. A soap solution is a more suitable option in this case. The fixing bolts of handlebar and strut support bearings should only be tightened to the required torque when the vehicle is back in its original position. This avoids distortion within the bearing, which leads to premature wear of the new parts.
Check rubber bellows and steering boots
Mechanics are also advised to check whether the rubber bellows on the landing gear joints are worn, damaged or leaking. If dirt particles have entered the joint, they could completely dissolve the inner plastic ball shell and damage the ball and the joint housing. This means that the joint clearance no longer meets the requirements. This is also the case if pitting corrosion become visible at the spring clamping rings of the rubber bellows. During steering, the track rod requires special attention: In addition to the rubber bellows, the steering boot needs to be checked for damage. ZF Aftermarket recommends press-out tools for dismantling the joints.
In order to guarantee customers increased driving comfort, workshops should consider using spare parts in original equipment quality. This ensures the optimal interaction of the various components. Under the Lemförder brand, ZF Aftermarket offers a comprehensive range of steering and chassis components in OE quality, characterized by a long service life and maximum driving comfort.