Just like a shock absorber, a suspension mounting kit is pushed around a thousand times every kilometre – over the course of 80,000 kilometres that means this small but important component has moved up to 75 million times. Imagine how that amount of work will deteriorate the rubber components in the mounting kit.
Worn mountings have an adverse effect on ride control and safety. Mount wear depends on the type of travel, driving characteristics and the individual vehicle, however a good guideline is that if the struts are worn out, the mounts will probably be worn out too. Therefore, suspension mounting kits should be replaced every time the struts are replaced.
Mounting kits provide a rubber cushion between the chassis and suspension, helping to reduce stress on the suspension by absorbing vibration. There is also a bearing in front mounting kits which allows the steering wheel to turn the suspension column and the wheels. It returns the steering wheel smoothly back to its natural straight position if released. Suspension mounting kits can affect the angle of how the shock absorber sits – if the rubber is worn, it can cause extra stress upon it and its surrounding components. Worn bearings also create knocking noises, something noticed even more in hybrid and electric vehicles due to the quietness of the engine.
How to diagnose worn mounting kits
Test driving vehicles (especially those over 80,000km) is a key part of diagnosing suspension issues, including mounting kits, and helps to explain the issues to the motorist. Find a short circuit near to your workshop that comprises the following tests:
• Bumpy road surface/speed bumps (feel for ride harshness)
• Listen for noises, feel for steering wheel vibration and any irregularities with the steering
• Turn the steering wheel and release your hands – does it return to its natural straight position?
• Pick a route by your workshop that is quiet, and one you can use repeatedly
• Aim for a 3-minute, 1.5 kilometre long route that includes a speed bump, a place where you can brake and accelerate quickly, and swerve safely. Your speed will not need to be over 50 km/h
When return to the workshop, eliminate any other factors such as any excessive movement in the other suspension components such as the ball joints and bushes.
Visual inspection tips
Broken / cracked metal – rubber joint: this could have been caused by aggressive driving or road conditions such as potholes and uneven surfaces. It can result in excessive vibrations transferred to the vehicle’s steering system and driver, decreasing comfort, increasing fatigue; changed damping parameters of the suspension; accelerated wear of the suspension and co-operating components.
Seized bearing: this could have been caused by incorrect installation if the full weight of the vehicle wasn’t applied when tightening the nuts to the required torque. It can result in excessive vibrations transferred to the vehicle’s steering system and driver, increased force will be required to move the steering wheel, the steering wheel will not return to a straight position once the steering wheel is released, and there will be noise coming from the suspension.
Deformation / relaxation of top mounting support bearing: this could have been caused by excessive axle load, or aggressive driving or road conditions such as potholes and uneven surfaces. It can result in excessive vibrations transferred to the vehicle’s steering system and driver, changed damping parameters of the suspension, and noise coming from the suspension.
When you have tested a car with worn mounting kits, and have completed the replacement, retest it! You will instantly see and feel a huge difference. This will give you more confidence when selling a suspension job next time around.
KYB offers a full range of full mounting kits with the part number prefix SM – this means the mount, bearing, and all nuts, screws and other accompanying items are included.
Take care when comparing the price of a mounting kits from different companies, many of them will not offer the full kit, which will influence the price of the unit.