A roller-coaster ride is great for a theme park. However, if your car pogoes, it’s time to replace those shocks…
There are many jobs we prefer to leave to the experts, especially the ones for which we have insufficient experience; aren’t equipped with the right tooling; or don’t have a car hoist. They’re factors that leave us no option but to pay the labour costs charged by workshops. You may be surprised to learn, however, that one maintenance job you could tackle yourself is rear shock-absorber replacement (the front shocks are best left to the experts because they’re usually MacPherson struts requiring specialist tooling).
A damper is a more accurate word for a shock absorber and it has two specifically designated duties that are regulated via oil passing through valves. The first is bump absorption, and the second is for the rebound to return the car to a level position. The bump needs a quick response to reduce the stress force through the car and passengers when hitting a bad patch. To test the shock absorbers’ action, press down firmly on a rear corner of your car and watch how quickly it rebounds.
Replacing dampers yourself
Let me preface this by saying that, if the shock is inside the spring, or it’s part of a strut, rather leave its replacement to the experts. You will require a pair of spring compressors that can be dangerous if not correctly fitted due to the stored energy that can be released if they slip off the coils. However, if the shock is located next to the spring, coil, leaf or torsion bar, it will be a safer bet for a money-saving DIY job.
I recently had to replace all the shocks on a SsangYong Musso 320 after the original 17-year-old shocks still appeared to be doing their job on tar roads, but poor-quality gravel roads exposed their fragility and they started leaking oil past the seals. Fortunately for the wallet, all four shocks were accessible without worrying about any springs. Some heavier cars, like the Musso, use gas-pressurised shocks all-round.
This is indicated on the shock and packaging, plus you may spot wire laced to the tube to prevent extension before fitting. If you do not fancy a free gym workout compressing the shock, leave the wire intact until you have fitted the shock to its mountings, then use a wire cutter to remove it. Be careful to check whether nuts and bolts are supplied with the new shocks, as you may be required to reuse the old ones. Some vehicles have an access cover inside the boot to reach the top nut, but this is not so with the Musso; the top nut is accessed from under the car. The flattened top-end of the rod must be held before the nut can be removed.
This took some time and one nut started turning with the rod, preventing removal. The solution was to take away a section of the upper steel sleeve with a hacksaw and angle grinder. This allowed access to the hardened centre rod. Gripping this tightly with a vice grip (a must-have addition to your tool box), the top nut could be removed. Replacement was much quicker than the removal.
The dangers of worn dampers
Tyre wear
For one thing, your tyres will begin to wear unevenly and you may find worn patches in places. This could quickly render a tyre illegal.
Loss of traction
Worn tyres are not only costly to replace, but represent a safety hazard. More importantly, though, worn shocks will cause your vehicle’s wheels to bounce off the road surface, compromising traction. This can lead to a serious accident. Rear shocks tend to go first. This is because they have varying loads of passengers and luggage to contend with, as opposed to the front suspension’s fixed load. The front suspension also tends to be set up stiffer in order to improve handling (especially turn-in), while the rear has a softer setup and a longer travel. You might find that the left rear shock will give up first as the road surface is usually more uneven near the gutter or shoulder, making the shock work harder.
The test
To accurately test the bump and rebound actions requires a shock-absorber-testing machine, but when a shock really has lost its ability to soak up bumps, as mentioned earlier, pressing the car down will result in obvious repeated oscillations in place of the normal single bounce before settling.
Author: Peter Palm
