RUBBER BUSHES

For such a simple component, flexible rubber bushes can cause the DIYer plenty of headaches: some of them are difficult to access and not especially easy to replace. Yet, while replacing bushes can save you money, doing so is not always the most cost-effective option.

Bushes defined

A typical bush separates two (or more) metal components via a flexible joint. They are fitted, most commonly, to steering and suspension mechanisms, including control arms, droplinks, dampers (shock absorbers) and suspension strut tops. Unsurprisingly, you will encounter different designs but most of them comprise an outer case made from aluminium, steel, or even plastic. The central flexible core tends to be manufactured from silicone, or natural rubber, which must resist degradation from movement, temperature extremes, sunlight, ozone and contamination from moisture, salt and oil.

Bushes aid movement and isolate both vibration and noise from being transferred into either neighbouring components, or the cabin. While bushes appear to be relatively straightforward components, carmakers and their suppliers pay great attention to their design and specifications. For this reason, manufacturers select different bush grades, dependent on the composite rubber’s compliance, ‘shore hardness’. As typical with passenger car design, the final decision tends to be a compromise – a factor worth considering, when considering upgraded bushes, because enhancing one characteristic could be at the expense of another one.

What goes wrong

As they endure friction, movement and exposure to the elements, bushes are not everlasting. MOT testers inspect bushes to ensure that wear does not result in excessive play, because worn bushes affect the efficacy and safety of the component to which they are fitted. Heat can cause the rubber material to harden and split, while oil contamination degrades and softens the flexible material, causing excessive movement. In addition, with no stated replacement intervals, you could encounter an older low mileage vehicle with worn bushes but a newer, higher mileage version with perfectly serviceable matching parts. This is one reason why car manufacturer maintenance intervals recommend frequent inspections, rather than fixed renewal periods.

Therefore, presuming that you service your car at home, do not overlook the bushes. Tears in the rubber, or evident perishing, tend to be obvious. Check also for breaks