Quote:
Originally Posted by LightningSS
I talked to a colleague, an ole gray-haired stress analyst, much older and wiser than I. We work on airplanes, but he is also an old school gearhead. He suggested looking into the vertical travel of the wheels.
As you know the wheels can move independently in opposite directions, and the purpose of the sway bar is to dampen this motion. Suppose the sway bar isn't there. Let's say each wheel can move up or down 3 inches until they hit the "stops" whatever that may be. So if the sway bar dampens that, ie, it keeps the difference between the two tires to something less than 6 inches relative to each other.
Say the max difference is 6 inches, meaning if anything forces the tires further apart the design load of the structure is exceeded and something has to give (PQ's bracket). And it probably takes a heck of a lot to exceed this.
So the OEM sway bar is designed to allow the 6 inch differential and keep on tickin'. The 6 inches is determined by the designers as the max travel the wheels will ever see in their lifetime plus some margin of safety probably.
Now you change out the OEM sway bar for a stiffer one. It is only going to allow 4 inches of differential until you hit the same design load in the structure. But, the wheels may still see the 6 inch differential in real life. What happens?
OEM bracket breaks.
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Well said sir. Overload and fatigue are primary suspects as are a number of other factors.
1. Lowering coils
2. OE sub-frame bushes
3. Light coil rate
4. Light damping rate
These factors would add to and increased loading of the sway bars and the mounting tabs. Earlier in the thread one post mentioned flexing of metal or wire and the resulting failure which is very similar to your post.
Other factors could include but are not limited too:
1. Violent Wheel Hop
2. Side Load Impact damage
3. Improper Installation
4. Design Limitations
We will work through the data we collect from this thread along with the data we collect outside the thread. We will have a definitive response as the end result.