In SF5 chassis (not sure about SG) there are 2 "wedges" or spacers sandwiched between the front x-member (engine cradle) and the frame where it is bolted to the frame, about 1 inch thick.

 

Has anyone ever tried raising the front roll center by removing these?

You're not talking about the rubber vibration dampeners are you?

i do not know what it's called. From tapping them lightly they do not seems like rubber to me (perhaps mine are already hardened from old age! ). I am certain that on WRX/Impreaza chassis the x-member is bolted directy to the framerail without these pieces in between.

So, let me get this straight? You're looking for more understeer?

Well not really. Let's leave the handling solution aside for the time being, although I am in the process of doing just that.

 

Rather, what I would like to find out is how these two pieces fit into the Forester's overall suspension geometry in comparison with the sedans sharing the same platform, e.g. WRX/Legacy/etc. It seems to me that by mouting the Foresters' x-member directly to the framerail should result in a higher front roll center. In fact I suspect the reason why Foresters have front-control-arms rear bushings that sit slightly lower (similar to Whiteline's Anti-lift Kit for the WRX) is to work with these spacers to keep the front geometry in tact.

 

I am just trying to see if anyone have done it before, and how the associated challenges are resolved, e.g. the pitch-stop rod needs to be shortened? tranny mount needs spacers? Will downpipe hits the body? Will it screw up the propeller shaft agle? etc.

It's part of the factory lift kit that was used to make foresters have a higher stance than impreza's. If you remove the spacers, it will give you increased ground clearance in the front, but give you more positive camber and decreased halfshaft life.

Good to hear about the increased ground clearance! The positive camber issue can be fixed with a camber plate even if it can't be resolved with the stock camber screw adjusted to max negative. In addition, instead of removing the spacer entirely some shims can be swapped-in to limit the effect.

 

But why would the halfshaft's life affected? I would worry about the lower ball joint's wear instead, as on WRX STI Spec C the ball joint seat on the aluminium arms were revised to have an angle instead of vertically positioned, so that seems to suggest that there might be issue that Subaru is trying to resolve.