Is it possible to change the aerial mast on my car? If I undo the mast it gets to a point where it just keeps turning & then can be laid flat. How do I remove the mast to change it for a different mast?

You have to pull harder than you think, almost unnaturally hard, it feels as though it's going to break!

Just as an extra bit of info, what a mission to get the original aerial off!   

 

I really had to pull beyond what I thought was reasonable. My long whip aerial had the security measure, so rather than be removable it would lay flat on the roof, for roof boxes and car washes etc.  It was shot tho, seems to have pitted terribly, almost like it's stone chipped!

 

As someone else on here mentioned, I eventually got it off by moving the aerial down to the lay flat position, since I was sure I would leave an outward dent in the roof.

 

Holding the base is also a must, since you could damage the seal if not careful!  It eventually pulled out leaving a long nail head type end as part of the screw.  I am not sure how this fixes in to the hole though. Perhaps there is something inside the screw thread that I have now made larger.  When I put the orignal aerial back in, it can now be removed easily, so if you do remove it you do lose the security feature.

 

I went for the Polo stubby unit, VW part number  6R0 035 849. It is up to 17 quid now with the VAT (July 2015).

 

Thus far, signal seems as good as the previous whip.

 

Edit, pictures uploaded. Last picture shows the end of the original aerial with the security stub type end.