Changing a car's shocks

Testing Your Shocks: How Much Bounce is Too Much?

The tires of your car are the only points of contact between your vehicle and the road. Shocks ensure that your tires remain touching the pavement, so you’ll want to make sure they’re in good repair. Fortunately, testing your shocks isn’t especially difficult.

Shocks Keeping Bounce Under Control

Your car’s suspension can be made up of coil springs, leaf springs or torsion bars to allow you to safely traverse uneven terrain and bumps in the road. Springs cope with acceleration, deceleration, turns and bumps, but oscillate — and would continue to do so if not acted upon by an outside force. In this case, the weight of the car controls oscillation.

Replacing Shocks May Require Only Basic Hand Tools and Safe Working Habits

Still, the weight of the car alone cannot control spring oscillation, which can lead to excessive acceleration, squat, brake dive, vehicle roll, or wheel bounce. In all of these cases, the driver would find the car difficult to control, and could even lose traction.

Testing Your Shocks: How to Know When “It’s That Time”

Perhaps the easiest way to test shocks is by judging their performance, but a visual inspection and “bounce test” can also be helpful in determining if it’s time to replace them.

In a clear parking lot, start with the car at rest. Accelerate hard and then brake hard. If the rear end keeps bouncing, your rear shocks may be worn. If the nose dips toward the ground upon braking, your front shocks may need replacement. On the road, if you find that your car bounces around a lot, has a hard time holding a turn or is affected by crosswinds, you may need new shocks.

The “bounce test” requires some effort. Go to one corner of the car and push down. When you let go, the car should bounce up, then settle back to at-rest height. If the car bounces more than twice, you most likely need new shocks.

A thorough visual inspection can also help you determine if you need new shocks, but you shouldn’t stop at just the shocks themselves. The shocks should be smooth (no dents), straight (no bends) and clean (no oil). Any of these conditions mean your shocks have been compromised. Additionally, check the status of your tires; if one or more have bald patches, it could mean your shocks are allowing excessive bounce.

Replacing Your Shocks: Time to Get Dirty

Shock absorbers come in three types: McPherson Struts, coil-over shocks and plain shock absorbers. Struts and coil-overs include a coil spring suspension, while plain shock absorbers are used in conjunction with a separate leaf or coil spring.

Replacing worn struts or coil-overs, since they are under intense spring pressure, can be dangerous. Special equipment is required to safely compress the coil spring, so the shock can be replaced. Also, because front McPherson Struts maintain alignment angles, an alignment should be performed after strut replacement.

Replacing plain shock absorbers, on the other hand, can be performed using a floor jack, jack stands and basic hand tools. Rear shocks on a pickup truck can take as little as 20 minutes, if everything is exposed. Sedans and other vehicles may require removal of interior trim, molding, or seats to get at the top of the shock. Always use correct lifting procedures and properly torque all fasteners.

For more information on shock absorbers and testing your shocks, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

about author

Benjamin Jerew

Ben has been taking things apart since he was 5, and putting them back together again since he was 8. After dabbling in DIY repairs at home and on the farm, he found his calling in the CGCC Automobile Repair program. After he held his ASE CMAT for 10 years, Ben decided he needed a change. Now, he writes on automotive topics across the web and around the world, including new automotive technology, transportation legislation, emissions, fuel economy and auto repair.

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