Ok, a question for all you setup guru's out there.

I am having an issue with my 12L4. In fact I have always had this issue to some extent.
The front end of the car "wobbles" alot coming into corners. It's like it grips, loses grip for a fraction of a second and then grips again. It will do this three or 4 times as I come into the corner. It always hold the line I want but can be a bit off putting with the front end moving around like it is.
I am running a 12L4 on ashfelt in modified. We do not use traction additive as we are not allowed too. But even when I have raced overseas where traction additve was allowed the car still had the problem.
My latest theory is the centre spring I am using is too soft so I have ordered some harder ones and will try them. Is there any other theory's out there?