Shock absorbers are an essential part of a car and allow for quiet and safe driving. However, vehicle suspensions wear out over time, making potholes much harder and harder to ignore. If your suspension is worn out, changing it is a job that can be done with the right tools and a little knowledge. Go to step one for more information.
Steps
Part 1 of 3: Getting started
Step 1. Make sure you need new ones
You may have noticed while driving that bumps and pits are no longer what they used to be, which means that the shock absorbers are probably worn and need to be replaced. A good way to test if the shock absorbers are actually dead and need to be changed is to press hard on the hood exactly above the wheel fender. Good shock absorbers should bounce once and quickly return to position. But if they keep bouncing then it's time to replace them.
Step 2. Purchase the new shock absorbers
When you replace them you have two choices: the springs are in good condition and can be reused or you want to invest and buy a whole new suspension set. The piston is a relatively cheap part, while the pre-assembled shock absorbers are more expensive, which leads many people to save the springs which is usually fine. Consult your vehicle manual or a local parts store to be sure you are purchasing the right shock absorbers or pistons for your car.
Inexperienced mechanics are usually recommended to purchase pre-assembled suspension. The removal of the spring can be done with a special bit that can be rented in spare parts stores, but there are mechanics who advise against it due to the high risk of accidents, which is to be avoided when compressing a metal spring with a pressure of about 200 kg. To be sure, buy the pre-assembled
Step 3. Consider upgrading the shock absorbers
You can find exact replacements for the shock absorbers you now have in your car, but the time to change them can also be a good opportunity for an upgrade if that interests you. More performing shock absorbers are suitable for those work vehicles that are used every day such as trucks.
- The spring shock absorbers they are made with a spring around the shock body itself which supports the weight of the vehicle and controls the movement of the suspension. They are adjustable, which means you can adjust the height of the vehicle.
- The double tube shock absorbers have a set of tubes, one internal and one external, in which the piston is housed together with a layer of liquid and air that have a tendency to create a foamy mixture that can affect performance, even if the modern versions have a nitrogen mixture to prevent the problem. They are common in off-road vehicles.
- The monotube shock absorbers they have a tube and two pistons that function basically like twin tube shock absorbers, with a piston separating the nitrogen layer from the air. They work well and are used a lot in trucks.
- The shock absorbers with reservoir (o reservoir) are filled with liquid and compressed air or nitrogen. When the shock absorber absorbs the impact, the liquid comes into contact with the gas, making resistance and attenuating the action of the spring.
Step 4. Jack up the vehicle in an appropriate place
Park the car on a level surface and loosen the bolts at either front or rear. Secure the machine on ramps and / or jack stands. Check the manual for the correct positioning of the jack. Once the car is raised, remove the wheels and find the shock absorbers.
The shock absorbers are fixed with a vertical screw that will be pulled out of the engine compartment or trunk, or it can be placed on top of a horizontal bolt that needs to be unscrewed and removed
Step 5. Check the shock mounts and spray metal cleaner on them
The hardest part of the job is taking out the old shock absorbers as they have a tendency to be sticky with time and wear making bushings and bolts difficult to remove. Check the supports to see if they are loose enough to take off or if the rubber around the bushings is likely to be breaking. Even if you do change your shock anyway, it's okay to spray a product like WD-40 and let it sit for a few minutes and then try to loosen the pieces and get to work.
Part 2 of 3: Remove the Old Shock Absorbers
Step 1. Remove the shock tower bolts
Many cars have bolts under the trunk, meaning you'll need to lift the fabric to reach the bolts and remove them with a ratchet or wrench. As always, consult your car manual for specific guidelines on where to find shock tower bolts. In general, however, they are located in the trunk.
To remove them, turn the wrench and the ratchet counterclockwise, if necessary lubricate the bolts with a liquid that can penetrate inside and remove the rust
Step 2. Unhook the shock absorber from the suspension
Use a wrench set or nut cutter to free the nut that connects the shock to the suspension and remove it from the bolt. If there is not enough space to use the nut cutter you can apply some solvent and heat the nut with a flame if necessary.
Depending on the type of mounting you may also need to release the lock on top of the brake assembly to reach the shock. Check the manual to be sure. Follow the same procedure to remove the nut on top and keep the nuts separate so you know which one will go in which place when installing the new shock
Step 3. Remove the shock absorber from the lower and upper bolts
This can be difficult, especially if the shock absorbers are mounted on pins with a mounting bracket and the whole thing is rusted. Move it for a while, it should eventually come off.
- One of the most frustrating things that can happen is seeing the connecting rod spin as you try to loosen the nut. You can use pliers to hold it steady while loosening the nut using a wrench, but even that can be frustrating. However, there are special kits that can be found in specialized shops and cost a few euros.
- It's okay to hit the bolt or wrench with a hammer to loosen it, but remember to put the nut on top. Don't risk misaligning the bolt and ruining the ability to reinstall the shock correctly. Let the metal remover work and take your time, it will be worth it.
Step 4. Remove the shock springs if you plan to reuse them
If you want to reuse the springs, use a clamp - not a hand-held one - to compress the spring and unscrew the cap on top of the suspension block to loosen the nut.
- Install the spring on the new shock by covering the new piston with the old cap, using tools to fit it if necessary, and reinstalling the spring by reversing the removal process.
- Again, it is better for inexperienced mechanics to buy new suspensions and throw away the old springs for reasons of safety and simplicity of the procedure, if the available budget allows it.
Part 3 of 3: Install the New Shock Absorbers
Step 1. Insert the new shock into the suspension control arm
You may need to apply force to compress the spring and insert it into place and you may need help to lift the suspension and put the bolts back in their exact position. It can be a question of balance, so it's best if you get help. Screw the nuts tight.
Step 2. Re-attach the anti-roll bar if you removed it previously
Re-attach it and retighten the bolts tightly. Replace the suspension tower nuts that you removed at the start of the job, probably in the trunk.
Step 3. Check the torque specifications in the manual
Before screwing back and tightening everything double check the torque specifications to make sure everything is in order.
Step 4. Repeat the process for the other 3 shock absorbers if necessary
Most shock absorbers wear out at the same time, so if you replace one you will likely need to replace all of them. Do this by following the same steps and then reassemble the wheels and tighten the nuts to finish the job.
Advice
- The shock absorbers should be replaced approximately every 120,000 km.
- Lubricate the shock absorber upper threads with a product such as WD-40 when removing the old nut.
