Flip transition of UINavigationController

Question

I have two different UINavigationControllers. Both are customized to present their own cool Navigationbar and have lots of ViewControllers with content.

I figured, it would be good to override the UINavigationController.

Now when I want to flip between the two UINavigationControllers the Navigationbar of the previous and next UINavigationController jump up and down.

After the transition is completed, the move back to their original y Pos. Any Ideas?

ViewController2 *VC = [self.storyboard instantiateViewControllerWithIdentifier:@"NavigationController2"];
[VC setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
id rootViewController = [[[[[UIApplication sharedApplication] keyWindow] subviews] objectAtIndex:0] nextResponder];
[rootViewController presentViewController:VC animated:YES completion:^{
    //[self removeFromParentViewController];
}];