I guess with enough will there's always a way, but it's not going to be easy.
Did the OP try the grinding paste trick?
No, not easy with typical 'our-type' tools at 28tpi. Pita to make a tight-fit or expanding mandrel just for that - but maybe, thinking about it, could be done carefully with outside jaws and a tailstock centre supporting a suitable centre-drilled bung for t'other end??? But wtfdik?
John's thread chaser is miles easier if grinding paste won't sort it - and cheap too.
(Just spent the pm taking the Öhlins off my XJR to clean up the springs and carefully paint them with rustproof agricultural-implement paint, as they have a few flakes off. Apparently, now we have MOTs upcoming over here, flaky paint on springs might be regarded as 'not good' by the jobsworth. Can't recall ever cleaning coil springs on cars, but there you go. New Ôhlins seem to be an arm and several legs . . . but they can't easily be dismantled for overhaul sadly for all sorts of 'risk of death' and 'noxious nitrogen gasses' reasons. So says the Book of Words. Bit like a Sprung Hub Trihard then!)
