I'm trying to replace the front control arms in my 2005 bmw 330ci (e46). I'm stuck trying to separate the inner ball joint on the passenger side. I'm using a pickle fork and a hammer. It seems that the pickle fork is fully inserted and the joint still hasn't separated. What else can I do to separate this ball joint?
I would recommend you a ball joint puller. Sooner or later you will need to remove a ball joint without replacing it, so a pickle fork is out of the question. Heating the control arm sounds a bit dangerous to me, so there is only the mechanical solution left.
Edit: Alternative solution: Since your fork appears to be too thin for the spacing you could insert a large/thick open-end wrench between control arm and frame and then reapply the fork
The easiest way to separate a ball joint is to hit the knuckle straight on. Hit it like you stole it. And I'm not talking about hitting the ball joint where the threads are at. Hit the metal part where the ball joint goes up through. Ensure you have something to pry it apart as you are doing it only so you can tell when it's actually separated.
EDIT: Here's an image of how I was talking about hitting it. Ensure the part of the suspension you are working on is fully off the ground. Also, ensure you loosen the castle nut, but don't remove it all the way. This will keep the lower control arm in check. It will also protect the threads of the ball joint in case you miss while you are swinging. You can usually find more room to work on the lower ball joint if you turn the wheel to the left or right completely. It usually works best if you turn it the opposite direction of the side you're working on, then swing from the back ... but every make is different. I believe the last Honda I worked on I did it from the back side. The method I've shown will work for any type of ball joint if done correctly (ie: tie rod end).
Are you sure you are using the right size pickle fork? If its inserted all the way and it is no longer pushing the two pieces apart, it sounds like its too small. Heat, hammers, and pry bars have their place but there's no substitute for the right tool.
I recommend getting something to pry apart the two then while prying, strike the outer part of the joint. If that doesn't work, you could try to expand the outer part with some heat. Propane might work but MAP or oxy-acetylene would be hotter and quicker.
That pickle fork is definitely too small. Then when you are using do not be shy with the hammer. These really take a beating to get loose. I restored an E36 M-3 and have pretty vivid memory of the fron suspension fighting me the entire time.
As @myself pointed out, that at some point you may want to separate a taper without destroying the boot. The separator is the way to go.