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Walt Fricke Walt Fricke is offline
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Join Date: May 2004
Location: Boulder, Colorado
Posts: 5,246
Curley
If one looks at the load paths, doesn't the top of the strut take very little force in a horizontal direction compared with down at the A arm? This is why I have always been suspicious of getting much benefit from strut bars. Of course, for a full on race car, you want even the small benefits. And there doesn't seem to be any significant disadvantage to go along with a strut bar.

A straight across bar has to benefit from a fixed diagonal in the vertical plane, so the forces on one side aren't just transferred to the other side, doesn't it? Again, maybe not much. An X or equivalent would be better (I did that on my track only car in a class with few restrictions), but as long as the loads are transferred to a stronger point, maybe a single fixed diagonal is enough.

It may be that the relatively low forces involved mean that the hinge pin effect of the strain gauge attachment doesn't matter?

Tperazzo, if he knows more about force paths than I do (which is not hard), reinforces my take about the front suspension mounts. The leverages with respect to those versus the forces at the axle are even more favorable to their not needing to be reinforced. Braking pushes the A arm backward. Vertical forces up front have to be inconsequential. If braking can try to pull the front mounts apart, well sheet metal does just fine resisting that, and the flat tubular sheet metal structure is plenty strong in compression as well.

I like the theories about the factory X brace. A race shop owner told me he favors it because it stiffens the front in case of collision, leading to somewhat less expensive repairs.

I have the strut brace on my SC cranked in as far as the hood/fender allows, just short of rubbing on one side. I wish I could get more negative camber.

If class rules allowed, I would widen the A arm in a flash. Easy enough to do if you can weld, and plenty strong. Because any shop could do this, there wouldn't really be a market for it, would there?
Old 01-21-2019, 05:03 PM
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