These are small, tubular-shaped blobs of (usually) rubber that form a slightly squishy link between the suspension and the car and, in the process, isolate a lot of the transmitted noise and vibration from the cabin.
Smack a normal steel hammer into the concrete, and now do the same thing with a rubber mallet. You can easily feel and hear the difference.
Suspension bushes are like little individual rubber mallets at each suspension mounting point. Without them, a car would be noisy and harsh with every little road imperfection able to upset the serenity inside the cabin.
Rubber bushes need replacing once they’ve worn out and are allowing excess movement at the point of attachment.
Age wears them, as does the constant pounding of kilometres over the years, but oil (usually leaking from the engine or transmission) also attacks the rubber compound and reduces its lifespan. So that’s one more reason an oil leak needs to be fixed.
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