BMW 1978-1981 Brake Switch Set.
For BMW Boxer all 80 to 100 S, T, RS, RT, from 1978 to 1980 no 1981
The axle that should be in the same hole as the standard brake lever has a diameter of 17 mm.
From 1981-1984 the diameter is 15 mm.
That's the only difference between those years.
Remember that we mean the year, NOT when they were registered.