passing data from one controller function to another

[eluser]newtonianb[/eluser]
I have an index function that loads a view with a form, this index function handles the validation of this form. If the validation succeeds I want the data to be passed along to complete a second form.

The way I currently have this setup is:

My index page is a form with form validation, if the validation succeeds the data of this form is sent to a different function within that same controller through url using redirect and passing data as arguments but my problem here is that i have to redo the validation all over again in the new function (and can't use form helper there).

How else could I send the data? The reason I want this other function to handle it is first its a whole different form of itself and second, I want the user to be able to quickly trigger my function from url.

Any help appreciated, please ask if you need clarification.