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Ignition Switch Disassembly

Ignition Switch Disassembly

From: (Stuart Scott)
Subject: BMW: Re: K bike ignition switches
Date: Sat, 01 Apr 1995 11:45:02 -0500

Tom Coradeschi, having trouble with his ignition switch asked…

> Any ideas/suggestions on how to separate the lock cylinder from the
> switch proper? It looks like the whole mess fits into a plastic sleeve.
> Needless to say, I’m a bit fearful of forcing the thing and buggering it
> all up.
> I just KNOW somebody out there can help me!

After removing the plastic endcap, the switch gear is contained in a plastic barrel unit. The unit is held in place by two pawl like clips:

                  key end
                |          |
                |\        /|  <- PRIZE THESE
   PAWLS ->     |_\      /_|     out
                ||        ||
                ||        ||
                ~          ~
                 switch end

located on the sides of the barrel unit.

Prize these apart (simUltaneously) and drop the switch unit barrel off the bottom of the unit.

From memory, there are two bridge units (90 degrees apart) held in with small coil springs, so put a rag unit the barrel to catch them on dis-assembly.

The guts of the unit looks like this (side view).

             |  key barrel |
             |             |
             |             |
             |{___|___|___}| <- CONTACTOR POLES
               | BRIDGE PIECE

Clean the outer edges of the bridge piece and contactor poles with fine emery or abrasive paste.

Assembly is the reverse of dis-assembly (I love that phrase!)

I find the symptoms of dirty contactors are;

  1. Intermittent missing
  2. Brake warning like comes on after a `miss’, indicating the ignition has been momentarily interrupted
  3. Faintly glowing ignition light

and do this routine about once every 18 months.

Hope this helps,


PS Never believe them when they say `NO USER SERVICEABLE PARTS INSIDE’

Stuart Scott Ph +64 4 472 8443
Coastal Tankers Ltd Fax 473 3690
Wellington, New Zealand Pvt 386 1590
President, Internet BMW Riders 1984 BMW K100
“…two cams, some valves, no turbo…”

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