I have been having a random problem with my RV8 (taildragger) where the aircraft tries to exit the runway in a right turn when the tail comes down on landings. This occurs about 10% of the landings, and is a mechanical initiation of some sort in the tailwheel assembly. The Brakes have been eliminated as a source of the initiation at this point. The cause of why the tailwheel initiates the right turn is a mystery. I make all my landings as wheel landings due to this unpredictable tendency. Most landings are uneventful but about 10% of the time as soon as the tail wheel is down I get a very strong right turn energy and most of the time I can over come it with left brake. Full left rudder only exaggerates the problem as it dissconnects the tailwheel and rudder as per design and the tailwheel is on its own. I have tried neutralizing the rudder which improves my braking leverage (foot angle). Recently this problem has become much worse and when it occurs and has resulted in two recent events where the aircraft ran off the runway with left brake applied. In both cases when I exited the runway and had decelerated to well under 20 mph I released the left brake and both time the plane swapped ends (ground loop) to the right. I have found the tail wheel wheel spring loose at the weldment receiver becasue the attach bolt had no nut on the bolt, and the bolt was loose. This was allowing rotation of the spring and the tailwheel. Rotation was approximately some 10 degrees or so transversly to the aircraft direction. The wheel fork additionally was also slightly loose but was more an issue as it caused additional rotation in the same arc as the loose spring bolt. I have replaced and tightened up all the connections and not yet flown it. Any thoughts on what is wrong in the tail wheel. My thoughts are that if the wheel is allowed to rotate on its edge that will result in an induced deflection and turn in one direction or the other, much like a bicycle or motorcycle. The continuity of right turns must mean to rotation is always one diirection. I would like techinical advice from anyone before I fly again.
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