Most people just replace with boxed lca. Lakewood is about the cheapest but still a great improvement above stock jegs sells them for about 89.00 for the lca and 89.00 for the rear pan hard bar They come with new bushings so its not a bad deal The factrory stamped ones flexed alot so you will see a inprovement if you box them in also. hope this helps

 

Could you please explain under what specific conditions the OE LCA's "flexed", what the flexed shape of the LCA's looked like, and how you were able to observe this?

Norm

 

He's not saying they are bent just that they flex while driving over normal conditions, such as taking corners fast. The stock LCA's are made out of a stamped U-shaped piece of metal that is more prone to flexing than a boxed version.

 

No argument that a closed cross section (like a square tube) is more rigid than an open section (like the OE channel).

But in order to make something flex you have to either bend or twist it. And those are not the primary loads that go into an LCA. All an LCA is supposed to see are axial compressive loads when you accelerate and tension loads when you brake. Period. Those loads do not generate any flexing. With an idealized pin-ended LCA, no other loads can be applied to the LCA's.

Buckling of the "sides" under acceleration is a "flex" situation that does become possible given extreme combinations of grip and power, though it's far less likely to occur in a torque arm suspension than in a 4-link. You'd never get anywhere near that point on the street with a small-block unless you'd done something as stupid as jacking the car up under the LCA and had put a kink in it.

Secondary loads that are generated in LCA's other than those attached with spherical joints do create some bending and twisting in the LCA's. How much depends on the type and stiffness of the bushing material. At any rate, from the driver's seat you would never notice the resulting LCA flex (ballpark estimates: 5 degrees of twist and half a degree of lateral bending at the maximum roll angle).

Given that you've installed the basic one-piece solid poly bushings in both ends of the LCA's, you have now added a significant amount of rear roll stiffness. The rear axle is now behaving like a huge rear antiroll bar, with the LCA's as the arms. You do have flatter cornering, true, but you have also just about guaranteed that the car will ultimately oversteer or spin, especially under such circumstances as wet/slippery roads, bumps encountered mid-corner, etc. IOW, times when you really want the rear end to behave itself.

This effect has been extensively discussed before and FWIW I'm currently in the process of putting the huge "LCA's binding" thread that used to exist over at CamaroZ28.com into Word format from hardcopy, as the CZ28.com administration pruned it from their storage. And I also have some other data that puts some numbers on this roll bind phenomenon.

Norm
Civil/structural engineer by profession
Car enthusiast by nature