BMW 2002 speedometers with high mileage, from 1972 to 1976, will usually end up having one specific problem that stops them from functioning correctly.
Inside of the speedometer is a heavy cast wheel. This wheel turns a shaft (by slipping a specific percent) that is in the center of an aluminum cup, which is connected to a spiral spring and the needle at the other end. The cast wheel is pressed on to a shaft that the speedometer cable attaches to at the other end. After years of wear, the cast wheel can spin on its shaft and move forward. This can cause the cast wheel to touch the aluminum cup. The result is a speedometer needle that is jumpy, turns to fast or even spins around to the stop pin, which can break the plastic needle on the late 2002s.
The repair is simple. Remove your speedometer from the instrument cluster and inspect the shaft where the cable attaches. If the shaft has any “in and out” play, it needs to be repaired. First, remove the 22mm nut from the rear mounting plate and then from the speedometer. Then remove the two small flat head screws that hold the rear housing in place. When inspecting the cast wheel and its shaft you will notice that the wheel has moved forward on the shaft. With the opposite end of the shaft against a hard surface, place a small socket in the center of the cast wheel. GENTLY tap the wheel back into place. There must not be any “in and out” play at the shaft, but also, no resistance when spinning the shaft. Reassemble the speedometer. When spinning the rear shaft, the needle should move 10 to 20 mph (with a slight resistance) and return quickly.
The earlier 2002 speedometers are designed differently and very rarely have the same problem. They also cannot be repaired the same way as the late style speedometers.
Author: Chis Joyner
Footnotes, Aug 1998
Tarheel Chapter BMW CCA