Part 1. Preparation and safety
Objective
- Check the serviceability of the shock absorbers and struts.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Shock absorbers and struts are located near each wheel and protect the passenger compartment from bumps.
- Many of today's vehicles are equipped with strut type suspension instead of conventional shock absorbers, but testing either system involves the same procedure.
- If a vehicle has adjustable shock absorbers, make sure that the shock absorber adjustments are the same for the left and right-hand side.
- Some shock absorbers contain pressurized gas. To prevent personal injury, do not puncture or incinerate these shock absorbers.
Part 2: Step-by-step instruction
- Check shock absorbers and struts
The simplest form of suspension test is known as a “bounce” test. Lean heavily on the fender or place your weight on a bumper. Release it suddenly and watch what happens. If the vehicle rebounds continually, you need to replace the shock absorbers. If the shock absorbers are performing well, the car will rebound once only, and then slowly return to its original position. While driving, the same test can be performed by stopping the vehicle suddenly from a very low speed. If the car “bounces” up and down a couple of times when coming to rest, you need to replace the shock absorbers.
- Visually inspect shock absorbers
Visually inspect the shock absorber mounting points for security and corrosion and note any wet looking patches on the sides of the shock absorbers. This is a common indicator that the strut or shock absorber needs replacing because of a fluid leak.
- Check strut upper mounting
Pay particular attention to the top strut mounting during the bounce test. Place your hand on top of the mounting during the bounce test. Any noise or movement in the mounting could indicate the need to replace the component. If you do feel movement, hear noise or see signs of leakage, report it to your supervisor.
Part 1. Preparation and safety
Objective
- Safely replace shock absorbers.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Suspension components support the weight of the vehicle. Make sure the vehicle is supported by something other than the vehicle's suspension system, such as a hoist or jack stands, before removing any suspension components.
- Some vehicles use the shock absorbers to limit the amount of suspension travel. In removing the shock absorber an unsupported part of the suspension may fall from the vehicle. If you are to remove the shock absorbers make sure the vehicle suspension is supported by suitable means.
- Strut assemblies contain a coil spring that is held under compression. Always use a spring compressor to release the spring pressure before disassembly.
- Always wear protective clothing and the appropriate safety equipment.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Shock absorbers are also known as dampers. Their task is to reduce suspension oscillations.
- The two most common types are strut cartridges and telescopic shock absorbers. Each type has a different shock absorber replacement procedure.
- Struts can be used for both the front and rear suspensions of front and rear wheel drive vehicles. The strut and spring assembly for each are basically the same with the difference being the types of arms and linkages that are used for its location.
- Due to the wide variety of mounting types there is no set method of removing and replacing a strut, so always refer to the manufacturer's manual for the recommended procedure.
- Always replace shock absorbers and strut inserts in pairs so the suspension has the same characteristics for left and right sides.
- Shock absorbers are rated for "Bump" - the rate at which they compress and "Rebound" - the rate they expand. They also have high speed and low speed valves.
- The high-speed valves are used when the shock absorber has to move quickly, such as over a speed bump or into and out of a hole in the road. The low-speed valves are used when the vehicle is cornering, braking and accelerating.
- A bounce test is not a true indication of the serviceability of a shock absorber. It does not test the serviceability of the low-speed valves.
- Shock absorbers operate by forcing oil through small orifices, or valves. This converts the movement of the shock absorber into heat. Too much heat will cause the oil to thin reducing the effectiveness of its operation. This is referred to as "Fade"
- Some shock absorbers are gas pressurized. It helps to reduce the effects of shock absorber fade.
- Shock absorbers can have the same mountings at the top and the bottom. Make sure the shock absorber is fitted the right way up.
- Shock absorbers use rubber mountings to isolate them from the vehicle body. Always replace these mountings when replacing the shock absorbers.
Part 2: Step-by-step instruction
- Remove telescopic shock absorber
If the shock absorber is not integrated with the strut assembly, make sure the vehicle weight is supported and then loosen the fasteners at the top and bottom of the shock absorber. Slide the shock absorber away from the mounting boss and remove it from the vehicle.
- Refit telescopic shock absorber
Fit the rubber mountings to both ends of the shock absorber and locate the unit on the vehicle. Fit the other half of the rubber mounts to the mounting boss and attach the fastener. Tighten the fastener to the manufacturers recommended value.
- Remove shock absorber from strut assembly
If the shock absorber is part of the whole strut assembly, you will need to remove that first before you can replace the shock absorber. Strut assemblies can be attached to a vehicle in a number of different ways, so refer to the manufacturers manual for the vehicle you are working on and follow the instructions on how to remove it.
- Compress the spring
Mount the strut assembly securely in a vise ensuring that you do not damage the casing, and attach the spring compressors to the coil springs and compress the coils.
- Remove the spring
Loosen and remove the nut that secures the top mount to the shaft. Remove the top mount and the upper spring cradle, and remove the spring.
- Remove the cartridge
Loosen and remove the nut that locates the strut cartridge within the strut housing and withdraw the cartridge.
- Fit the new the cartridge
Fit the new strut cartridge into the strut housing and tighten the securing nut.
- Refit the spring
Fit the bump stop to the shaft and fit the compressed spring. Locate the upper cradle and top mount on the shaft and tighten the securing nut. Loosen the spring compressor while guiding the spring into its correct position within the upper and lower cradle.
- Refit the strut assembly
Refer to the manufacturers manual and follow the instructions on how to refit the strut assembly. Repeat the procedure for the strut assembly on the other side.
Part 1. Preparation and safety
Objective
- Lubricate suspension and steering components to the manufacturer's specifications.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Many older vehicles on the road had numerous lubrication points. Today's vehicles have far fewer, if any, points that need lubricating.
- Clean lubricating equipment very carefully. If you don't thoroughly clean the fitting or nozzle before pumping the grease into the fitting, dirt could be forced into the component.
- Any dirt entering a component can cause premature failure.
Part 2: Step-by-step instruction
- Determine location of lubricating points
Check the shop service manual to determine where the grease points are and the type of grease required. The manual will also indicate which components have a lube fitting or if an auxiliary lube nipple has to be temporarily fitted for the function.
- Check and clean the equipment
To start the lubrication job, clean each of the lubrication fittings and the lube gun nozzle by wiping them with a clean rag. This should be done before you attach the nozzle to any of the fittings. In some instances, you may need to remove a component’s plugs and temporarily install a lubrication fitting. After the component has been lubricated, you must re-install the original plug.
- Lubricate the component
Now that you have cleaned the fitting and nozzle, push the lube gun nozzle over the fitting. The nozzle must completely cover the fitting, to ensure the pressure of the gun forces the grease through the fitting into the joint. Add enough grease to see the seal or rubber boot rise slightly. Under no circumstances should you overfill a lubricated joint with grease. This can rupture the seal or rubber boot or bellows. Make sure that the grease does not leak out from around the nozzle end. If it does, check that the fitting has been properly cleaned, so as to allow the nozzle to go all the way onto the fitting.
- Check and repeat
If the fitting is clean, remove the grease nipple and check for blockage. If so, it must be replaced with a new fitting of the same size and angle, and the joint re-lubricated. Remove the nozzle from the fitting and wipe away any excess grease from it. Repeat the procedure until all the appropriate joints have been lubricated.
- Complete the service
After you have completed lubricating all the appropriate joints and cleaned off any excess grease, it is appropriate to attach a sticker to the windshield. This will tell the owner when the service was carried out and when the vehicle could be due for any service. Lower the vehicle and remove it from the lifting device.
Part 1. Preparation and safety
Objective
- Check front and rear suspension components and measure their wear.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- The components of the vehicles suspension system are designed to operate as a whole unit. Some vehicles use very sophisticated systems, while others use very simple systems. That means that there may be components on one vehicle that are not found on others, or the materials they are made from differ. Generally, more sophisticated systems contain more components made from more exotic materials.
- The term 'bushing', used in this topic as a component name, may be more familiar to you as 'bush' or bushes'.
Part 2: Step-by-step instruction
- Check coil spring
Remove the tire and wheel assembly to gain better working access. Check the coils for any signs of cracks or fatigue, such as any nicks or scores on any of the coils. Also check the insulating block between the top of the spring and the vehicle body for signs of splitting and chaffing. Any deterioration should be reported.
- Check McPherson strut upper mounting point
Check the upper mounting point of the McPherson strut for tightness. Ensure the spring insulator is in position. With the vehicle on the ground, ask an assistant to turn the steering wheel from lock to lock. Place your hand on the top of the strut mounting as it is turning, and note any noise or feeling of roughness from the top bearing
- Check leaf spring
Check to see if there are any leaves of the spring that are cracked or broken. Also if the spring has noise deadening inserts between the leaves, make sure they are in place. Check the security of the spring center bolt and that the “U” bolts are tight. At the ends of the spring “eyes” are used to locate the springs in position. Check the condition of the bushes or mountings and spring shackles. You can check these by putting a lever in between them and levering against the spring.
- Check the suspension to body mountings
Inspect the bushes or rubber mountings for any signs of deterioration, swelling or crushing. Check the tightness of the bolts. Report any loose mounting bolts or retainers to your supervisor. These joints can also be a source of body noise that can be difficult to diagnose.
- Check vehicle height
Replace the wheels and lower the vehicle. Check that the tire air pressures are correct, and then measure from the bottom of each wheel rim to the center of each wheel arch or opening. Record your readings. After you have completed measuring both sides and front to rear, compare the readings to the manufacturers specifications. If there are any differences in height, you will need to consult the shop manual for the allowable tolerances. Any major differences in the readings could indicate that the suspension springs are worn and have sagged. Report the findings to your supervisor.
