[yupetc]

Originally Posted by acmurda

Also noticed that since the E70/F15 use same bars. People may want to just try an E70 Oem rear sway bar which is 24.6mm compared to the 22mm found on the f15. Thats assuming its stiffer, because diameter alone does not determine stiffness, properties and quality of material used is a big factor. The 22mm in the f15 could be just as stiff as the 24.6mm on the E70.
I'm just really hoping the almost $1000 Canadian I just spent on the aftermarket bars I mentioned above is going to be a worthwhile investment.

I think you may be onto something great here. There are only so many materials to choose from, and from one platform to another (and E70/F15 being so close in semblance) I do not suspect BMW would prescribe a material change unless the previous material either shows signs of failure or if the new material will substantiate savings to change onto. And in this case you're proposing, BMW has no real incentives to make the change. In fact, they do get cost savings by directly coming to a smaller diameter sway bar, which is evident here. And I did drive a E70 X5 for about a year, I can safely say that the E70 body roll is much less than these F15's are.

So yeah, I think you may have found the optimal/economical rear sway bar solution to our ever-so-lacking aftermarket support on the F15's.