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Sparco Stress Bar

Modified Sparco Strut Tower Bar
Rigid and convenient

I knew that I wanted to add a strut tower bar (stress bar) to my M3, but I was not happy with any of the commonly available designs. It appears that most of the bars on the market are designed with aesthetics as the primary concern, and strengthening the chassis as an afterthought.  Furthermore, I personally believe that aluminum is a poor choice as a material for a stress bar.  If for no other reason than the fact that aluminum has an endurance limit of zero (i.e. it will eventually crack, no matter how strong you make the part).

I wanted a steel stress bar.  I thought about designing one myself and having my friend Sean McLean fab' it up.  But the ends of the bar where it meets the strut towers are a little complicated.  So I purchased a Sparco steel stress bar.  It cost $96 and I got it from Rod Millen Imports in Huntington Beach (Sparco p/n 03677).  The Sparco bar is made from 1.5" tubing.  I estimate the wall thickness at about 0.050" based on the weight of the bar (it is very light).



Straight out of the box the Sparco bar did not fit my car very well.  This was probably more a problem with my car than with the stress bar. In any case, it was OK since I planned to modify it.  The Sparco bar bolts to two of the upper strut bearing studs on each strut tower.  But the mounting plates bend down over the insides of the strut towers.  Then a hole is drilled through the side of the strut tower and a third bolt is located here.  See the picture for a better description.



Thus, as it comes from the factory, the Sparco bar is not easy to remove.  However, Sean and I modified it so that I could take out the center portion with a minimum amount of hassle.  We added a pair of flanges near each end of the bar (see picture).  By removing the four bolts that go through the flanges I can pull out the center section of the bar in about 60 seconds.  This is helpful when the stress bar is in the way of working on the engine.  This is similar to the "hinge" design that is employed on many of the alloy stress bars but it is stronger because it still offers some resistance in bending as opposed to only in tension/compression.



I am very happy with the way the modified Sparco stress bar turned out.  It is light, convenient, and still very strong.



Home
Back to Installs
place holder
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Installs Part-1
Installs Part-2
Installs Part-3
Ground Control Suspension
2.5 L Engine Rebuild
M Coupe Diff Cover
Custom Ergonomics
Sparco Stress Bar