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Discussion Starter #1
The frame rails on the Impala are not a boxed design....instead they are an "L" bar. This bar will flex (unlike a boxed frame rail) a lot! The frame rails on my 81 El Camino (with an LT1) are the same, and I have broken 4 Hotchkis and 2 PST bars. On the last broken Hotchkis (they replaced all of their bars in a few days - terrific service from Hotchkis) bar I closely inspected the frame rails and say that they were showing some flex in that they were no longer straight, but rather kind of "wavey".

The LT1 is very "torquey" and will twist the frame.....do it enough and you'll snap the sway bars (any make!) at the bolt holes. It'll be interesting to see if the redesigned Hotchkis bar will hold up. I really think the only solution is to box the frame, and that is one hell of a job to do.
 
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What sway bars are you talking about? The front or rear?

The rears I think break becasue of the rear suspension flex when the suspension is at an extream angle.

Yeah.. The frames do suck on these cars. Comeone, They have what is it, 2 cross members? 3 with the tranny crossmember, and 4 kinda with the buick brace.

A custom boxed chassis would be awesome. :D Imagine an Alloy chassis. That would shed some weight off these cars.
 
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I don't believe that that's the reason. The rear bars aren't connected to the frame, only to the lower control arms.
If you are talking about the front bar, the swaybar-to-frame bushings offer plenty of play so that the frame would have to flex A LOT to break a bar. Besides, the bar is thicker so it would win.
The reason for the failure is probably the combined effect of stress concentration and fatique due to cyclical loading. Material and heat treatment are also factors. (In some older notrhern cars corrosion could also play a part).
Tim
 
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I need to learn to type faster, someone always manages to put a post between me and what I was responding to...

A 30 foot ladder has about 30 cross members, but it still twists a lot. Even more than our frames.

What kind of alloy?

Tim
 
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