Strut tower deformation, also known as mushrooming, is one of
those problems that continues to plague MINI owners in all drives
of life, from track cars to cruisers. It seems like the sheet
metal that serves as the mount for the front strut towers was
made far too weak for the strength of the suspension. If the
mushrooming is drastic enough, it can affect the behavior of
the car. Many MINI owners have had to take a 2x4 and a hammer
to their strut towers to bang the metal back into place.
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 The
deformation occurs either over time through continuous
small events or sometimes all at once with a large event.
Likely events can include bottoming out the suspension
due to catching air, running off the road or track, or
even hitting a large pothole, among other things. All
of these conditions impart a force on the thin metal that
holds the strut tower that it was obviously not designed
to withstand. Using finite element analysis (FEA) software,
we can analyze the effects of large forces on the strut
tower.These first two images show the relevant pieces
of a simulated strut tower. Some of the model has been
suppressed to make it easier to see. This model is not
meant to be completely accurate with respect to the Strut
tower of the MINI, however the shape and contact points
are approximately correct and the properties of the materials
are accurate.
From the factory the strut tower provides a flattened
surface for the strut to rest against. This is important
for maintaining straight alignment and proper suspension
geometry. Using this model, we simulated an extreme case
of the “car” essentially being dropped, as
if it were to have jumped off the ground or fallen off
the road. The deformation is readily apparent, but to
make it easier to see we have enhanced the deformation
to make it easier to see. The following image are the
results of that fall. Following to see, will be a colored
image. The color shows the amount of displacement from
the original position. Blue means little or no displacement,
moving towards red which is the maximum measured displacement.
It is apparent that a hard impact to the strut tower from
below will deform the metal. This has been seen on many
MINI’s in the last few year, and this simulation
serves only to validate the effect. While the mushrooming
of the strut tower is not something that is guaranteed
to happen, given the frequency of the effect it is definitely
something to be mindful of. |
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 M7
is mindful of strut tower mushrooming, and has developed
a solution that will help prevent it from happening. The
Strut Re-inforcement Plates bolt to the strut tower using
the stock bolts that hold the strut in place, sandwiching
the thinner sheet metal between two more rigid pieces
of metal. This sandwich serves to distribute the force
of an impact over a much larger amount of metal, resisting
deformation. The following two images show the same simulated
strut tower with the SRP’s installed.
The SRP equipped strut tower was then exposed to the exact
same impact force as the preview, non-SRP model. The results
make a very strong case for the advantages of having the
reinforcement plates installed. not equivalent to the
previous colored images. The same green or red color does
not equal the same deformation from pre-impact in the
two sets of images.
 As
you can see, mushrooming is almost completely prevented,
even in one of the most extreme cases we could simulate.
Even with the deformation enhanced, it is difficult to
see the mushrooming occurring with the SRPs installed
on the strut tower. Even in less extreme instances, it
is clear that you can protect the integrity of your strut
towers using M7’s Strut Tower Reinforcement Plates.
The M7 strut tower bar provides the same protection with
the added benefit providing extra structural rigidity
to your frame. The only question now is which product
is right for you? |
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