Why does the 4S shop only replace one shock absorber?

[SanLeo]

It is because only one shock absorber is leaking oil, so only the damaged one needs to be replaced. Introduction to automotive shock absorbers: Automotive shock absorbers (including suspension springs), as the most important component in a vehicle's vibration damping system, are responsible for absorbing vibrations and impacts caused by uneven road surfaces during driving, thereby providing a comfortable ride for passengers. When a shock absorber is damaged, the vehicle may experience excessive bouncing and instability during driving, which can even severely affect driving safety in serious cases. Lifespan of automotive shock absorbers: Under normal circumstances, automotive shock absorbers do not have a fixed lifespan. As long as there is no oil leakage, internal rubber aging, cracking, or other issues, they can continue to be used.

[VanLondon]

As a long-time Camry owner with 15 years of experience, I've noticed it's quite common for 4S shops to replace single shock absorbers. Last time when my right front shock was leaking oil, the mechanic explained that the decision mainly depends on wear condition. When there's significant wear difference between two sides, replacing just the faulty one can save you about a thousand yuan. After all, new shock absorbers definitely perform better, and pairing it with an old one may cause slight imbalance, but practical tests show limited impact. Of course they'll also tell you - if both sides are aged or there's obvious uneven height, then you must replace them in pairs. I chose to replace just one side initially and drove for over a week. Going over speed bumps, I could indeed feel the new shock being more stable, but there was slight steering pull. Eventually I replaced the other side too - actually the mechanic had suggested this more conservative approach from the beginning.

[Karl]

Back when I just graduated, my car made a loud clunking noise over potholes. The 4S shop inspection revealed the left rear shock was leaking oil. When I asked why only this one needed replacement, the technician squatted under the car and showed me: the right shock had 60,000 km but wasn't leaking, and its damping test still met specifications. Replacing just one saved me 40% in costs, and the new shock performed significantly better than the 6-year-old original part. They recommended keeping the still-functional old component as an eco-friendly approach. The key point is that if the travel difference between sides exceeds 3mm, they must be replaced in pairs - my car measured only 2mm difference. On the drive home, I specifically compared bump absorption, and the new shock side indeed felt more responsive. However, after three months, I noticed body roll during cornering remained pronounced, so I proactively replaced the other side when I saved enough money.

[DeAmara]

Workshop mechanics often encounter car owners complaining about replacing just one shock absorber. There are three key points to consider: if the tester shows the damping coefficient of the old shock has degraded by no more than 30%, it can be retained; there should be no height difference between the two shocks on the same axle; and there should be no chassis deviation. Last week, a Magotan had a leaking right front shock, while the left front still had 85% performance left—replacing just one saved the owner 980 yuan. However, note that it's safe if the new shock's damping coefficient is within 10% higher than the old one; exceeding this can cause uneven stress on the anti-roll bar. We always remind owners: if you frequently drive on highways or often have passengers in the back, it's recommended to replace them in pairs. Tests show that when driving over speed bumps at 30km/h with a single new shock, the difference in body sway between the old and new shocks is about 15%, which is acceptable to 80% of owners.

[LaMaverick]

From a female driver's perspective: During my last maintenance service, they told me the right rear shock absorber was leaking oil, but I insisted on replacing both. The technician then removed both left and right shocks, placed them on the ground, and pressed them to show me - the left one clearly rebounded much faster. Using instruments, he measured that the right one had completely failed while the left still retained 70% functionality. Replacing just one OEM part saved me 860 yuan, and the remaining old part could last another year or so. He specifically taught me self-inspection methods: Close windows when going over speed bumps and listen for clunking sounds (unilateral noise means it's broken), or check for symmetrical water marks on wheel arches after rain. It's been four months now with no issues, but the technician advised taking turns slower and coming back promptly when the other one fails.