A500 vibrations

These vibrations has been going on for quite some time now, the same week after week, but today when I was going to a friend it suddenly didn't matter at all how I treated the gas while the gears changed. & after a while came a growling sound around 60 m/h so I turned back home.
Now I wonder if someone has experianced the same but with a different cause compared to the rearest roller bearing..?