Mushrooming of the strut tower on the Mini Cooper seems to be a big problem. The one fix that I found was made by Craven Speed. This item is called the Strut Top Defender. Craven Speed makes a plate that mounts on top of the strut tower.
Quote from Craven Speed:
Infectious G Spots
Whether you are competing at an autocross or driving on a Sunday afternoon your MINI is at risk. Unless you already have some STD’s, you ought to catch a few just to be safe. Because around every corner, in the very depths of every pothole, and the pinnacle of every bump G forces lie in wait. The occasional G may seem harmless by itself, but at times there may be several lurking in one rut and once they have done their damage to the sheet metal atop your tightly sprung strut towers, it will be difficult to resume normal activity.
Mushrooming
A picture may be worth a thousand words, but you may not be able to detect the mushroomed strut towers if you looked at a thousand photos. Less than one inch of tower deformation can be extremely detrimental to your MINI’s alignment. This has been a common issue that MINI owners have had to face. It is a compromise in the design of the vehicle, where the tight springs allow for the griptastic handling that we love on the twisties, but are the main reason that our MINI’s have a unique disposition for sheet metal deformation.
STDs (Strut Tower Defenders)
Craven Speed STDs are a preventative measure. Instead of suffering the consequences of a lack of protection, using STD’s to your advantage will strengthen your MINI’s strut towers before deformation can occur. By sandwiching the sheet metal between the strut and our 1/2 inch thick aircraft aluminum plate, it is strengthened ten-fold. STDs come in pairs, one for the right tower and one for the left. Craven Speed STDs retain a 1/2 inch thickness throughout ensuring that there are no weak spots. Installation is easy, using the included instructions, it will take about 10 minutes to ensure that you do not have to go through a lengthy and expensive alignment repair. You do not need to lift the car, and the only tool needed is a torque wrench.



