Filter wp_nav_menu()

I think I got the answer:

function my_nav_menu( $args = array() )
{
    $echo = isset( $args['echo'] ) ? (bool)( $args['echo'] ) : true;

    $args['echo'] = false;

    add_filter( 'wp_nav_menu_objects' , 'my_filter_nav_menu' , 100 , 2 );

    $menu = wp_nav_menu( $args );

    remove_filter( 'wp_nav_menu_objects' , 'my_filter_nav_menu' , 100, 2 );

    if( $echo )
        echo $menu;
    else
        return $menu;
}

This does the trick: lets me alter the menuitems and custom args are still available.
I accidentally hooked the filter into wp_get_nav_menu_items instead of wp_nav_menu_objects.
I still having problems with the filtering, however these are probably some logical bugs..

EDIT: i’ll solved my problem by combining navbar level 2 and navbar level 3+ into one and separating them with css

heres the current php part:

function serthy_filter_nav_menu( $items , $args )
{
    $argArray = (array)( $args );

    if( isset( $argArray['toplevel'] ) )
    {
        foreach( $items as $key => $item )
        {
            if( $item->menu_item_parent != 0 )
                unset( $items[$key] );
        }

        return $items;
    }

    global $post;

    $arr = array();

    foreach( $items as $key => $item )
    {
        $parentIDs = get_post_ancestors( $item->ID );

        foreach( $parentIDs as $i => $parentID )
        {
            if( $parentID == $post->ID )
            {
                array_push( $arr , $item );

                break;
            }
        }
    }

    return $arr;
}