Replace strut top mountings sooner, aftermarket brand explains why

Technicians should also look to replace strut top mountings when changing shocks and springs

Replace strut top mountings sooner, aftermarket brand explains why
Strut top mounting should be replaced sooner and with OE parts to deliver better driving handling and comfort.

Suspension brand, Febi Bilstein believes that strut top moutnings need to be replaced at the same time as other suspension components, and has explained how the part is integral to the popular MacPherson strut.

Febi Bilstein said the Macpherson strut is made up of a number of components, which forms a compact suspension unit, this is a very popular choice, for vehicle manufacturers, due to its simplicity and low manufacturing cost.

The main parts of this suspension unit comprise a long telescopic tube, which incorporates a damper, this is usually fitted with a piston protector to keep out road grit, to protect the piston and seals.

The coil spring is located between the two retaining cups, this is held in place under compression, by the retaining nut, which is secured to the top of the damper piston.

The unit is rigidly connected to the stub axle or hub assembly at the lower end and is pivoted at the top, usually by a top bearing, to accommodate steering movement.

The bearing forms part of the strut top mounting assembly, which acts as an insulator as well as a fixing point, between the suspension unit and the vehicle’s body.

A suspension strut top mounting is a bonded rubber bush, which is mounted to the top of the damper and fixes it to the vehicle’s chassis.

Integral part of suspension assembly

Strut mountings, can also incorporate a bearing or a bearing plate that allows the strut to turn with the steered wheels.

The strut mounting acts as a coupling to the spring and shock absorber, connecting it to the body.

The damping force is absorbed separately within the mounting, which in turn insulates the vehicle’s body from suspension and road noise.

In the lateral direction, the mounting is designed to be stiffer.

Febi Bilstein said this positively influences the driving dynamics and the steering response, which greatly reduces noise, vibration and harshness from the driveline and suspension, ensuring maximum driver and passenger comfort.

To do this, the strut top mounting has to ensure low-friction and distortion-free movement of the shock absorber spring during steering and deflection, enabling the road spring to operate without self-aligning torque.

Also, it has to locate the shock-absorber spring, and form a support surface for full deflection of the shock absorber.

This has to be achieved in a compact design that has been optimised for limited mounting space, and supplied as a sealed unit and to be maintenance free.

During the life of this suspension unit, the damper and spring have to expand and contract millions of time, enduring the stress of all the road surfaces that the vehicle is driven on.

This includes unmade and damaged road surfaces, which bring extra stress on this unit.

Not replaced enough

During any maintenance work that is carried out on this suspension unit, it is common that the shock absorber or the road spring, are replaced because of wear or failure.

The strut top mounting is often only replaced as a distressed purchase when the suspension unit is stripped down for repair, or only when the driver of the vehicle complains of any excess noise from this area.

The strut top mounting bearing race, often falls apart or has seized, resulting in a creaking or grinding noise from the suspension, this can lead to the bearing tearing the rubber apart in the mounting (below).

Steering and handling problems

Rubber itself can deteriorate with age, leading to reduced driving comfort due to noise development, resulting in tight steering or excess play in the steering, unstable handling and reduced driving and braking safety.

The strength of a strut top mounting comes from the properties of the elastomeric material used and metal reinforcement within it.

This gives it the flexibility and stiffness that is required.

The picture below shows a sectioned view of Febi part 22639, with the bearing.

Strut top mountings should be replaced sooner and with OE parts to deliver better driving handling and comfort.

When considering replacement of this part, Febi Bilstein has said to rely on tested OE-matching quality spare parts.

For more information on the entire range of suspension strut top mountings, click ‘more details’ below.

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