I'm sure this was debated in the past, but I want a new round of opinions, especially from any mechanical engineers that care to share. For now, let's leave the SFC's like Spohn's that attach into a dozen spots out of the equation, and concentrate just on the style that just connect the front and rear subframes. The Alstons are tubular steel, and others are boxed. The type of twisting that the chassis experiences is likely to exurt (sp?) compressive forces and twisting forces on the SFCs. The compressive strength of either should be more than adequate, but generally it's going to be determined by the amount of material, which would give an edge to the boxed SFCs assuming that they use the same thickness steel and have the same external dimensions (not corner to corner, but flat to flat). Now for the twisting forces. Isn't tubular steel stronger than boxed steel with twisting? I would think that with the steel, all of the force would be dumped on the corners because the force would become a shearing force between the 4 sides. The tubular shouldn't get that type of shearing force, but just a rotational force that would be evenly distributed throughout the entire tube. It would seem that for rotational, the tubular would be stronger. Overall, does anybody have experience with both styles, and any sort of stats that show which is stronger?

Am I right, or am I just full of crap?

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i asked this a while back and in general the responses i got favored boxed. i made my own, sort of copied several peoples ideas and put it all together in one SFC. i used 2x1 1/2 and 1x2 square and 3x1/8 flat. a side advantage of the box tubeing is i could weld it to my floor and the lip that the factory jack hooks on, i also added a flat pad for a jack point.

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Ed,

Cool idea for the jack pad! I'd vote for enclosing the original LCAs as well. The original design is almost adequate in the form of a channel. Closing the box makes for a very rigid member. And we all know how good it can be to have a rigid member...

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Later,
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Round tubing is stronger against tortional and angular forces...but square is better for forces parralel to the sides. For most any suspention application, the forces on any one piece is pretty limited to the 2nd kind, so square tends to hold up better. This includes SFC's.

 

that jack pad idea is a definite benefit. many a tire monkey and such will set the rack at the easiest point. you definately do not want your pinch welds at the rocker area crushed. by the way jim,,,how are those nick tahou garbage plates tasting lately. used to live in rochester for many years.

 

I boxed my LCA's in and I have had no trouble with them.

 

Excellent! I haven't been in Rochester since May, but when I go back in November, that'll be my first stop!

I'm debating whether to make my own SFCs or what. From the looks of Empire's, they don't look very difficult to make. I liked the Alston's though because they seemed to cradle the front and rear subframes instead of just having a flat plate to weld to it. It seems like a lot of stress would be on the weld with Empire's, where if the whole thing cradles the subframes, not only is there much more surface that's welded, but some of the force would be on the sides instead of the weld.

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The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

 

Jim I was thinking that Empires 2 point SFCs look easy to make too. Once I free up some cash I'm gonna look into renting a welder, "box" my rear suspension parts and make SFCs for my car.

oh Jim I've been in Alex's IROC with Empires SFCs it defiantly makes the car stiffer. Reminded me of a sick ride in an amusement park. I don't remember what his car was like before them, but it's a noticeable difference from Nates (69 Mustang) IROC. oh yeah Alex's cat was hitting the SFC when under WOT. I think he just took a mallet and whacked the cat to fix it. Alex's SFC Page

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