Question 911 front strut steering knuckle, bump steer Options

[Krieger]

I know there are shops out there that raise the spindle on bilstein struts then heat and bend the steering knuckle down to help with bump steer. I plan on lowering the front suspension about 1.5" by using the adjuster. I have boge struts and want to know if anyone has done just the heating and bending of the steering knuckle, does it work to counteract bump steer, is it hard to do acurately?

[Eric_Shea]

The important take away I'm getting is the relationship between the tie rod v the a arm.

The important take away I'm getting after looking at what are supposedly correct configurations (1, 3 & 4) is the tie-rod v the steering rack (or the ground). With raised spindles, which the factory did on certain RS's and all RSR's, it would be the tie-rod relationship that is changed.

If you want bump steer to truly not be a factor it is essential to actually measure it on your setup, instead of making assumptions about what happens. There are dissimilarities between the arc of motion of the a-arm and the tie rod even when they are set parallel at rest.
On my race car, I use a combination of rack spacers and bent steering arms to minimize the effects of bump steer.

So in my situation Chris, I would measure and use the factory 108 +/- number and add 18mm to the acceptable difference (Koni struts with spindles raised 18mm)?

Adding rack spacers wouldn't help with the center of the torsion bar so, would I add the width of the spacers to the acceptable number as well?

How much to bend my spindles on those if need be?

[ChrisFoley]

So in my situation Chris, I would measure and use the factory 108 +/- number and add 18mm to the acceptable difference (Koni struts with spindles raised 18mm)?

Adding rack spacers wouldn't help with the center of the torsion bar so, would I add the width of the spacers to the acceptable number as well?

How much to bend my spindles on those if need be?

My technique is to bend the steering arm equal to the amount the spindle is raised, then use rack spacers to correct for any additional lowering. You could also use heim joint tie rods with spacers of 18mm and rack spacers, or all tie rod spacers.
What I meant by "actually measure it" is to use bump steer measuring tools and move the strut up and down with no torsion bar installed. Bump steer tools use a flat plate bolted to the hub and two dial indicators to show the steering effect as the strut is moved. It is a trial and error process to move the bump steer effect to a part of suspension travel where it has less influence.
You want the bump steer to be minimized close to ride height, especially in compression. In rebound any bump steer will have little effect since the wheel is unloaded.