How Low Can You Go?, Have I gone too far? Options

[Joseph Mills]

It never ends... (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Corner balanced my car recently and acheived a "cross" reading of 50%. (IMG:http://www.914world.com/bbs2/html/emoticons/wub.gif)

However, instead of my front A-arms being level, they now angle downward towards the center of the car. I have read that you do not want to go beyond "level" to maintain correct steering geometry. How does this adversely affect geometry? For that matter, what is"correct steering geometry"?

Where do you check for levelness? The arms get thinner as they go out towards the wheel. Measuring under them with a level , I'm about a 1/4" too low. But measuring under the "seam" of the arm I'm level (By seam, I mean the flange on the side of the arms where the upper & lower halves of the arms are joined). Which does one go by?

My steering rods are also tilting down a bit going towards the center.

Here is the current ride height with Kumho V700s measured at the doughnuts:

LF 3 5/8" RF 3 6/8"


LR 4 2/8" RR 4 3/8"


Anyone else running this low to the ground? What are some of your measurements?

I'm sure I can achieve the same "cross" with the car slightly higher, although it will mean losing some of the current rake (not all).

Suggestions? Observations?

Have I just gone over the edge? (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[eeyore]

Well, I was wrong on another thread, so I'll shoot for 0-for-2 today.

Bump steer is one aspect...

The ideal situation is to have the a-arm and the steering arm be the same length, that way their ends cover identical arcs through suspension travel. That usually doesn’t happen, and may not be desirable for other reasons (see Ackerman?)

So what happens is the a-arm and steering arm are different lengths, and their ends describe different arcs through their travel. The factory sets the car up so they swing through as complimentary arcs as possible in their normal operating range (green boxes).

If you lower the car too much the operating range changes (red boxes). When you hit a bump, the wheel goes up, the arc of the steering arm is radically different compared to the arc of the a-arm, causing the tire to turn inward or outward, depending on the differences of the arcs.

The usual way to address this is to add spacers under the steering rack (on 914s) so that the steering arms range moves back into the green boxes.