When you find these kinds of Mushrooms, it’s bad news. No, we’re not talking psychedelic fungus, but rather a common problem affecting the BMW E46 3-Series (as well as the BMW 3 Series). Unfortunately, the fact is, the OEM strut towers of your BMW E46 3-Series are a weak point of the car’s suspension and chassis, and so the forces acting on your shock absorbers or coilovers are also acting on the strut towers, flexing them slightly and slowly but surely stretching them out. Ironic that despite its great handling, the wear and tear on the BMW E46 Suspension itself is the problem.
The end result of which is more stretch than the elastic of Peter Griffin’s Tighty-Whities. Take a look at this example Mushrooming on an E46 with just 36k miles on it (Image via Rogue Engineering):
So what’s happening here?
BMW Engineers have long been in a struggle to shave weight wherever possible as they’ve added more and more features to [...]