Nasty vibration coming from the rear brakes

[Martin306]

The tires are balanced.

It must be the drums.

I'd still swap back to front just in case any weights have come off that you've not noticed.

How did they suddenly become warped? Think about it, you've only changed the shoes, no?

Another point to note, sometimes cheap shoes can give you this problem until they bed in, I had a vibration issue on my 106 drums and I filed a chamfer on the leading edge of the shoes which fixed the vibration.