Understanding suspension bushes

Thursday May 31 2018

suspension bushes

Suspension bushes 

By David S. Mukooza

Bushings are an integral part of your car. They are commonly known as “bush” by most mechanics. Bushings are cushions made of rubber, polyurethane (often shortened to “poly” or “urethane”) or other materials. They are mounted on car suspension and steering joints to absorb road bumps, control the amount of movement in the joints and reduce noise and vibration. Bushings often take the form of fat, rubbery washers through which suspension components or the bolts that attach them pass.

According to Ronald Lubega of Grace Lubega Motors in Rubaga, on any car, bushes are found where there is a joint in the suspension. He says bushings cushion movement between two solid parts, helping to absorb shocks and vibration. This limits noise and leads to a smoother ride.
Although there are different bushes in the suspension system, some of the more commonly replaced ones are wishbone and control arm bushes, anti-roll bar drop links, anti-roll bar bushes and shock absorber bushes and mounts. Here are some examples of classic symptoms of bad bushings and why they occur.

Metal wear down
It is without a doubt that some car parts are made of metals and worn down suspension bushes can result in metal-to-metal contact of suspension parts. Lubega says this contact can cause stress to these parts and cause them to wear down too. The parts that can become damaged tend to be more expensive and harder to replace than the suspension bushes, which is why it is so important to replace them the moment you realise they are worn out.

Lack of control in steering
According to Bosco Kigongo, a mechanic, when the bushings are worn out, drivers may experience a lack of control in steering, as well as a bumpy ride. Controllability and breaking is a crucial part of any vehicle, and so suspension bushes need to be working to maximum efficiency. “When bushings wear out, the driver may feel funny noises from the front of the vehicle, or hear clunking or rattling noises on rough roads, when turning the wheel or in hard braking. Drivers may also experience poor handling or loose steering,” he says.

Abnormal creaking and clunking noise
Kigongo says worn suspension bushes can also lead to abnormal creaking and clunking noises while driving. Suspension bushes that are no longer able to carry out their function properly can lead to parts clunking together when they should not be, or can result in a stiff movement that results in creaking.
He adds that failure of rear suspension bushings may be harder to detect as they do not involve the steering system and may be less affected by cornering.

Premature tyre wear
According to Lubega, like bone-on-bone contact, worn bushings can allow metal-on-metal contact. Worn control-arm bushings can allow the vehicle’s front end to slip out of alignment and once a car is out of alignment one of the very first indications is premature tyre wear.
“What feels or sounds like worn shocks or ball joints, or another suspension problem, may not be the fault of the part itself but the bushing that cushions joints and mounting points. A thorough suspension bushing inspection should reveal the culprit. For example, a loose stabiliser bar will allow more body lean (and perhaps noise) in turns, but if the bar is not bent or broken, maybe only the bushings need replacement,” he says.

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Squeaks
Dried out bushings can also be a source of squeaks. Initially older cars had grease fittings which require regular lubrication along with oil changes while the more modern “permanently lubricated” bushings in today’s cars have simplified regular maintenance.
The downside is that they are not always truly permanent and once a bushing of this metal-encased design dries out, it may have to be replaced entirely to solve the squeaking.

Lubega, however, adds that bushes wear gradually over time so it can often be difficult to spot a problem if you drive the car on smooth roads. This is why he recommends regular checks with your mechanic to expose faulty bushes and have them replaced immediately.

How often should you get a suspension alignment?

A suspension alignment should be performed on a regular basis to ensure proper tire to road traction, stable steering, and overall mechanical health and longevity of the suspension parts.
The typical amount of time between alignments is three to six months; however, driving in rough conditions will shorten this period. Every time your vehicle crashes into a pothole, the suspension system is pounded with tremendous amounts of force.

The weight of the vehicle combined with the speed and momentum cause considerable stress on suspension parts, every time you encounter a bump. Even if you do not drive off-road, most public roadways have deformations that put your suspension system through its paces.

When to replace bushes and cost

Most drivers think that mechanics are the only ones to identify faults in a car. However, sometimes we need to identify these problems by ourselves. According to Bosco Kigongo if your bushes are severely worn out you may be able to feel or even hear a difference in the car’s handling. There could be vagueness in the steering, poor handling or braking, knocking, rattling or creaking from the suspension.
However Kigongo says visually inspecting the bushes is one way to know if they need replacement. Over time, the material degrades and it should be obvious if they are cracked and badly worn. It is not an exact science, some worn bushes may look fine but could still be due for replacement.
Remember there several types of bushes including anti-roll bar bushes, suspension bushes and wishbone bushes.

Because of the amount of labour associated with installing new bushings on some vehicles, the overall cost can be high relative to the bushings themselves. New bushings, though, can markedly improve the ride and handling of a vehicle that’s been in use for several years.
According to Ronald Lubega, a mechanic, some bushes are easier to replace than others, but most are quite complicated and detailed. They can take a lot of physical strength to remove and some will need specialist pressing tools. In some cases it can be more economical to replace the entire component rather than just the bush. For example, for the time, effort and expense it takes to press out a wishbone bush, you might be better off replacing the whole wishbone.
Lubega adds that Anti-roll bar bushes are the most commonly replaced bushes as the anti-roll bars are constantly twisting, he says most mechanics actually find these easy to replace.

Cost
According to Mohammed Ssemakula, a spare parts dealer in Kiseka, prices of bushes range depending on the size and type of car. He says for the rubber bushes for small SUVs and second hand ones range between Shs15,000 and Shs20,000. He, however, says the metallic ones are more expensive. He says for a car such as a TX Land Cruiser, a brand new metallic bush might go for between Shs140,000 and Shs150,000 from any Toyota outlet.
However, Kigongo maintains that it is a good idea to have someone inspect the suspension bushes regularly. He advises drivers to ask their mechanics to do this at service time and before you invest in new tyres or tracking. Worn or damaged bushes are not always obvious, but they make a huge difference to how a car drives or moves.

dsmukooza@ug.nationmedia.com

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