I am in the process of replacing the front strut inserts with Bilstein Touring (Economy) strut inserts. When I assemble the insert, the large threaded fitting that holds the insert in the strut tube does not seat all the way down, however it is tight and there is not movement in the insert body. There appears to be a ring at the bottom of the tube (and I remember having these in older 240's). Is this ring necessary to properly seat the insert or should it be removed with the Bilstein Touring shock?

Thanks for your help!