your supposed to drop the subframe to fit new arms as you cant get the bolt on the gearbox side, back in the correct way, as you will have found out. i replaced both of mine just before the mot, i didnt drop the subframe, to much of a fuck on, and mine hasnt had a problem. but id id be checking the subframe alignment, and tracking, as a first port of call. changed the bottom arms on my MK1 years ago, didnt drop the subframe to do that either, and it drove like a boat after, it was all over the place, eating tyres and all sorts, so had to get the subframe dropped and realigned.