问：我需要更换驾驶员侧的下部控制臂。我也应该更换乘客侧吗？

好问题...通常，在汽车零件方面的决策规则是“测试，诊断，测量和确认”，然后再花钱代替可能非常好的零件。尽管该建议不适用于诸如火花塞之类的磨损物品。那里的规则显然是在“ x”里程数之后自动扔掉的。尽管可以测试乘客侧控制臂并验证其状况，但您知道它已经有18万英里。That is a lot of miles, it probably is worn, and so it would not be "unreasonable" to just simply replace it, particularly when you consider that the vehicle will have to be aligned after the driver side arm is replaced (it’s impossible to PROPERLY align a car with worn parts). So, hyper-technically, although you do have the option of inspecting the passenger side arm to see if it is still serviceable, I probably would replace it. Additionally, and getting back to the issue of the necessity of a good post-repair alignment, while you are doing this work you have to evaluate the condition of the other suspension parts, such as the tie rod ends, bushings and so forth. Any wear in the front suspension, in excess of what is allowed and specified in the Factory Service Manual will make it quite literally impossible to align the car to preferred factory specs. If you desire, a certified mechanic from YourMechanic can both更换控制臂在此过程中，请检查其余的悬架，以查看是否还有其他问题需要解决。