Here is a quick discussion on what I found on bump steer. The 818 started to get a little more twitchy so I checked the toe in. The original alignment was 1/16 inch toe in. When checked, the toe in was1/4 inch. Evidently the suspension had settled a bit over the years. Suspecting a bump steer problem I checked the toe in with the car jacked up to the point the wheels were just touching the ground. At that point the toe OUT was 1/4 inch! There was a 1/2 inch change!

This weekend the bump steer parts arrived and I made a gauge to measure it. The following graph is the results.

bump steer front.jpg

Spacing is the distance from the bottom of the steering knuckle to the center of the heim joint.

From the fully extended suspension system (0) to almost fully collapsed 5 1/2 inches there was a 3/4 inch change in toe in per wheel. The width of the tire is about 24 inches. The change in toe in was measured on a 20 inch board. Needless to say it was shocking how bad it was! Yet the car handled great in the curves.

A second issue that made the problem worse, was to get ride height I was 1/2 inch from the limit of travel. The absolute worst place to be on the curve. The plan is to drop the ride height 1 inch and take the occasional scrape. This would put me in the flat part of the curve. Each data point is 1/2 inch of travel.

With 2.24 inch spacing the car is more stable. Before the change the car seemed to want to dive into curve. Probably what was happening is loading the outside tire with excessive toe in it grabbed the pavement more pulling it deeper into the turn. I have done some dumb things with it that scared me and should have spun out, but it has always behaved perfectly!

I now feel in hard corners it wanting to slightly over steer. I know there have been problems with bump steer from the rear resulting in people spinning out mid curve

Moving to the future, first is lower the ride height, realign the suspension, and correct any problems with the rear bump steer. The learning never ends!