Essential advice for rubber-to-metal part removal and installation

Check rubber-to-metal parts regularly and replace in pairs, ZF Aftermarket advises

Independent garages are being urged to check rubber-to-metal components when inspecting vehicle suspension components.

The advice, issued by ZF Aftermarket, states that any defective steering or suspension part can put the safety of passengers and other road users at risk.

A ZF Aftermarket spokesperson said: “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.”

The specific dimensioning and shaping of the RTM has an influence on the chassis tuning: it improves steering behaviour and driving stability supported by suspension strut support bearings, subframe bearings, control arm bearings, stabiliser bar bearings or axle beam bearings.

Depending on the make and model up to twelve different RTM can be installed within the chassis system.

Hydraulically damped bearings

Other crucial parts – in addition to conventional rubber bearings – are hydraulically damped bearings namely axle housing, axle beam and control arm bearings.

The spokesperson added: “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.”

If a defect is detected ZF Aftermarket says affected parts should be replaced immediately – ideally in pairs for maximum safety.

Installation and removal of rubber-to-metal parts

Prior to dismounting, it is essential technicians pay attention to the position of the bearing in order to identify any installation-relevant positions.

ZF Aftermarket generally recommends 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.

The spokesperson said: “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.”

The track rod requires special attention, according to AF Aftermarket which states that in addition to the rubber bellows, the steering boot should be checked for damage.

It 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.

For further information about ZF Aftermarket, click here.


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