Another alignment thread!

I'm not sure what you mean by "over turn". If you mean the steering wheel does not want to return to neutral (straight ahead) position by itself, after completing the turn, that is mostly caster. When you are turning the front end lifts up slightly, and the weight on the front end will want to return to it's lowest position by returning the stg wheel to its neutral position when you release the stg wheel and it spins back in your fingers.
If the caster is insufficient AND/OR the suspension is riding on or very close proximity to the control arm rubber bumpers, this will prevent stg wheel "return".