It is inevitable that driving over some bumps during your driving experience. Then moment when you drive across a hump, potholes or other irregularities, there are many force from outside to against the suspension. The front spring suffers from that and the coil spring insulator is designed to decrease the possibility of damage. The coil spring insulator is made of a tough rubber and it is located at the top and bottom of the coil spring. With the coil spring insulator, you will feel a huge shake or vibration when you drive over the bump. Here are two ways to check if your coil spring insulator is failing. If there is excessive road noise transferred into the passengers cabin, or if there is a grinding noise when turning. Do wait until it is too late. You must be shocked by the expensive labor cost in the store. That's why we are here. You can get a BMW genuine coil spring insulator with a cheap price here and replace it by yourself.