It wasn’t that long ago when struts needed to be replaced around 50,000 miles. This was the average mileage when a unit’s performance would begin to degrade.
Over time Strut performance will naturally degrade due to driving conditions, but some factors can speed up the performance loss and cause early signs of damage or wear. One factor that can lead to early wear is oil leaks. Less oil inside the unit means less internal pressure. Less pressure means the oil can more easily aerate, causing foam to form. Foam and bubbles can be compressed which means they do not pass through the valves the same way. As a result, the strut is not able to dampen suspension movement effectively.
Another main reason, why shocks wear out is simply because they live a hard life. Even when driving in normal conditions down a smooth road, struts can stroke an average of 1,750 times per mile. Inside the strut, a piston’s movement travels up and down inside a tube. Due to its performance, these components naturally will wear down over time. Sometimes the oil can become contaminated with dirt or debris. Contaminants might enter from outside of the strut passed through the seals, or from the inside due to the internals wearing down.
And let’s not forget, if the strut is wearing out, the springs will have to work even harder. This can cause the springs to wear out and fatigue sooner due to the added stress. Inconsistent ride height from corner to corner and poor ride quality will lead to failure and safety risks.
When it comes time to inspect a strut there are a few important things to look out for. First, how much oil is too much oil? The seal keeps the oil and nitrogen inside of a strut assembly but may leak trace amounts of oil and gas. As the shaft travels past the seal, some oil will stick to the shaft, but we are talking about microscopic amounts of oil for every stroke. This oil will eventually become visible on the outside of the strut body.
Visually inspect the strut for broken or excessively rusty springs. If a spring breaks entirely it will make quite a racket. A strut might be broken if one corner of the vehicle is sagging lower than the rest. In some cases, the broken section of spring can end up puncturing the tire, causing a blowout or damage to other related components.
Any inspection should also include a road test. During a test drive you should be pay close attention to excessive bouncing after hitting a bump, front end dive under braking, rear end squatting under acceleration, and excessive body roll going around a corner. Keep an ear out for any abnormal noises you may hear while going over bumps. It helps to have a designated driving route that includes different conditions to test the performance in different environments. It’s hard to replicate a customer concern if we don’t drive the vehicle in the same conditions to better understand the differences or changes.
Today’s struts have a longer service life than before. Ride control is a critical piece of vehicle safety and should never be overlooked. Over time they will start to degrade and eventually wear out. This is exactly why it’s so important to inspect ride control components whenever a vehicle is in your shop.
