I am attempting to put coilover sleeves on a '85 golf. I have to use stock replacement struts as per my rules. The problem I have is that the sleeve won't fit over the struts end cap that holds the rod and piston in. I've measured the sleeve and the strut's body, and it would fit perfectly, but I can't get it over the end cap. I notice that the end cap is threaded onto the strut body. I am worried about removing the cap as I would imagine it holds pressurized oil. I would like to hear your ideas.

Thanks,
Scott