Yeah, it's
fairly straightforward.
Sequence is as follows and all work is done on the "drive side":
Remove the wheelnut & cone locknut
Remove the lockring and lift off the sprocket
Unscrew the cone nut and lift out the small bearing set.
Unscrew the one piece goldie coloured clutch driver.
Leave the bigger bearings sitting in the hub shell
Put some fresh grease on the balls and on the helical thread of the new jb adaptor
Thread it into the mechanism, in place of the one you lifted out
Drop in the small bearing set, freshly greased
Thread on the cone nut
Thread on the cone locknut and tighten up snug with no play but also no binding on the cones
Leave your original sprocket, lockring and driver to one side - keep for future use.
Thread your new regular freewheel onto the jb driver like you would with a regular hub
Go ride!
Hope this helps!
Brian.
(ps it's bendix, not britax)
(pps have a look at flatlandfuel.com - in the links section, go to "freecoaster maintenance" and click on "suntour diagram" - this gives you a good exploded view of a suntour coaster hub, and the bendix driver and setup is pretty similar to this. Bp.)