Airhead Tech Pages


BMW slash 5 Ignition switch R & R

Bill Confer


This weekend I decided to replace the broken plastic slider that covers the ignition switch on my '71 R75/5. It turned out to be a little more work than I anticipated, but it was worth it. Looking at the ignition hole sitting out in the elements was getting to me. :)

Here it goes:

Disassembly

1.  Disconnect the battery
2.  Remove the headlight
3.  Look for the four metal tabs holding the switch circuit board to the
        headlight housing.  They need to be bent straight to allow the
        circuit board to be pulled down.  I used a small screwdriver
        and a pair of needle nose pliers.  The steel is very strong and
        difficult to bend.  Don't bend it any more than you have to, you
        don't want to break one off.
4.  Once the tabs are straight, pull down the circuit board.
        
        CAUTION!  Many small parts will fall out of the switch above
                        the board.  Try to gather them all up, I'll
                        tell you how they go back in later.

5.  Now you should have all the parts out of the switch assembly.  The
        chrome cap on the ouside of the headlight bucket is held on 
        by metal tabs also.  Bend them straight and remove the chrome
        cap.
6.  The plastic slider goes through the metal cap.  There is a small 
        spring that attaches to both of the "legs" on the slider, and
        around the metal post that's riveted into the headlight bucket.

Assembly

7.  Attach the small spring to the "legs" of the slider and put it through
        the chrome cap.  Place the spring around the post and attach the 
        cap to the headlight bucket and bend the tabs over to hold it in place.
8.  Now comes the fun part, you may want to recruit an assistant.  
9.  Insert the chrome ring up into the headlight bucket.  It's keyed,
        so make sure it's oriented correctly.  The ridge goes up.  A little
        grease will hold it in place.
10. Insert the chrome "barrel" up into the hole with the spring/ball bearing
        side up.  Make sure the cut out section is oriented correctly toward 
        the rear.
11. Insert the key from the top while holding the chrome barrel in place.
        DO NOT insert the key into the barrel while it's out of the
        headlight bucket!  You'll spend a lot of time searching for the
        ball bearings that fly out.  (Don't ask)  The ball bearings hold
        the key in place, and they are held in by a clock type spring
        wrapped around the top of the chrome barrel.  
12. With the key inserted, the chrome barrel will stay in place.
13. Insert the small brass cylinder into the bottom of the chrome barrel
        with the plastic tip down.  Again, a little grease will hold it in
        place.
14. Place the large spring around the chrome cylinder.
15. Place black plastic washer/spacer in it's slot on the brass armature
        and slide it up on the chrome barrel with the contact point of 
        the armature pointing toward the front of the bike. (this will
        require compression of the spring.
16. Slide the circuit board up over the metal tabs to hold the switch
        assembly in place.  This may take several tries to get everything
        lined up.  It took my wife and me about twenty minutes and a
        whole lot of cussing to get it right.
17. Bend the tabs over to hold the circuit board in place.  They're
        strong and require a lot of force to bend them, be careful not
        to break the fiber circuit board.
18. Remove the key, and make sure the contacts on the front of the board
        hit each other when it's reinserted.  Bend the contacts if
        necessary.
19. Connect the battery and make sure everything works.
20. Install the headlight.

Have fun, getting that switch back in correctly is a treat. Take your time, and don't break off any tabs or you'll be looking for another headlight bucket. I expected to find screws not tabs, but our friends in Germany must have decided the switch would not be taken apart very often, and it shouldn't. It's very simple, and there's very little to wear. The most common problem I've seen is missing or broken plastic sliders.

Bill Confer     92 R100GS       71 R75/5
Indianapolis    conferw@lilly.com


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Last Update: 11 September 2010