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Thread: /5 ignition switch replacement

  1. #1
    Registered User ebeeby's Avatar
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    /5 ignition switch replacement

    Has anyone seen any illustrated directions on /5 ignition switch replacement? My switch failed (I have power to the front left terminal of the board when looking inside the bucket) and I have replacement parts en-route for the switch as well as the switch plate.

    Eric
    1973 R75/5

  2. #2
    James.A
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    Eric, this is the most difficult operation I have undertaken on a /5. You will need a long punch, a hammer, an appropriately sized clamp, some thread or dental floss, and a helper. To remove the circuit board, you will need to locate the four metal tabs that hold it in place in the head light shell, they are located near the four corners of the board. Next you must get under these tabs(known in the auto industry as "toy tabs") with a thin blade screw driver and pry them up until they are straight or nearly so. A small needle-nose plier might be helpful also. The cylinder of the lock/switch mechanism has a spring in it so when you relase the last tab, you or your helper should put your thumb on the bottom of the circuit board and grip the entire assembly against the headlight shell to prevent parts from being expelled.

    Matching up the wires from the old circuit board to the new one is the easiest part. With the old board dangling, switch the wires on the terminals from the old board to the new one, one terminal at a time. At least one of the terminals has 2 wires attached to it.

    BE ADVISED:The following proceedure was developed by me and may or may not comply with approved practices and methods. Use at your own risk. JAS
    On the bottom of the switch cylinder assembly is a copper shoe that effects the light switching function when the "key" is turned right or left. The entire switch cylinder assembly is held in place against the circuit board between the board and the top of the headlight shell with spring tension when installed on the 4 toy tabs in the headlight shell. Additionally, there is an elliptical band spring that holds a ball bearing on the internal shaft. This is the part that holds the "key" in place when in use. (note the grooves cut into the shaft of the key) DO NOT REMOVE THAT SPRING OR BALL BEARING. Don't even lubricate it, especially not with WD40.
    Compress the entire switch assembly with the shoe in place and clamp it together. I used the corner of the jaws of a bench vise. Take a length of thread or dental floss and tie up the assembly in such a manner that it will stay compressed when released from the clamp. Place the compressed assembly on top of the circuit board with the shoe in the longitudinal position.(lights off) Now you must fit the board/switch assembly in place in the headlight shell with the 4 toy tabs protruding through the 4 corresponding slots in the circuit board. Have your helper take the long punch and hammer and bend the toy tabs over to hold the board and switch cylinder in place. When the board is securely tabbed in place, cut the thread to release the spring tension. Do not try to remove the thread.Take extra care with the toy tabs. If you break one off, your'e screwed.

    Good luck and take yor time on this one. If I can do it, you can do it as well.
    James A......

  3. #3
    Cannonball Rider #52 darrylri's Avatar
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    Take a lot of digital photos of everything before you start and as you disassemble. Make sure they're clear enough to see where everything goes before you take it apart.
    --Darryl Richman, forum liaison
    http://darryl.crafty-fox.com

  4. #4
    Administrator 20774's Avatar
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    Be careful with those "tabs". On the various vintage forums, people mention this when trying to remove the circuit board from the /2 machines...they can be brittle and might break. I can't imagine the fix is easy, either...
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
    Registered User ebeeby's Avatar
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    James - Thanks for taking the time to share a nicely detailed experience.

    Eric
    1973 R75/5

  6. #6
    James.A
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    Quote Originally Posted by 20774 View Post
    Be careful with those "tabs". On the various vintage forums, people mention this when trying to remove the circuit board from the /2 machines...they can be brittle and might break. I can't imagine the fix is easy, either...
    Kurt, the only fix that I can envision for that problem is a replacement headlight shell. I got away with doing that operation twice on one of my bikes. I dread the thought of another attempt. It is guaranteed that if you bend the tabs enough times, They WILL break.

    Darryl, I took pictures of the connections for my R27 rear fender lights. They turned out too dark. Good thing there are only 3 wires. Detailed pictures are a GREAT idea.

    Eric, please feel free to print the text of the posting for reference, and when the time comes, call my cell phone for guidance. 309-251-0877.

  7. #7
    Cannonball Rider #52 darrylri's Avatar
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    Quote Originally Posted by woodnsteel View Post
    Darryl, I took pictures of the connections for my R27 rear fender lights. They turned out too dark. Good thing there are only 3 wires. Detailed pictures are a GREAT idea.
    The voice of experience. DAMHIK.

    --Darryl Richman, forum liaison
    http://darryl.crafty-fox.com

  8. #8
    Registered User ebeeby's Avatar
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    I got the new switch installed. the thread idea was the trick. Reminds me of when I used thread to hold gaskets in place on a 1960 Cadillac water pump 30 years ago.

    Anyway, having torn the bike down and zeroed in on the ignition switch, it turned out I had a shorted Westco battery. You know the drill. 12 volts, dash lights, put a load on it , everything goes black, then 20 seconds later lights appear again. My VOM showed 11.65 volts. It wasn't until I pulled the battery and put my load tester on it that I exclaimed "oh, S*&% !! ".

    But the ignition turn cylinder was worn out where the key notch engages the cylinder for turning to headlight/parking light. The switch plate itself looked fine and I tested all the solder joints for a cold solder and they were all good. So I'll send the $231 Bob's BMW replacement plate back leaving the new $71 switch cylinder in place (I never installed the switch plate so Bob's will RMA it).

    ALong the way I got to learn about how exactly the switch works, and BTW, the new cylinder did NOT come with the ball bearings or plunger tip so I had to transfer those from the old switch - no big deal. This switch is a perfect example of German thinking (something I have had the opportunity to see on my Porsche 914 and 986). A simple design, but pretty goofy by American standards. Workmanship on both switch plate boards (old and new) looks like something from an 8th grade shop class and would never survive ISO standards in the Telecom world I inhabit.

    I should have remembered what the old guy in Mississippi said when trouble shooting an electrical problem: Step one, remove battery and throw it in the river. Step two: put in new battery.

    Thanks for all the guidance. I am now officially a /5 ignition switch veteren.

    Eric
    1973 R75/5

  9. #9
    Registered User skiteach's Avatar
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    1st step in every manual I've read; Disconnect battery. Audi factory service rep then wanted to see 12v at a terminal! We were tracing a cruise control fault. It was a real DUH moment!
    '73 R75/5
    Never had a bad day skiing!

  10. #10
    Baile82604
    Guest

    80RT missing Problem should be a new thread, but

    I don't know how to yet.

    Went to the Husker Rally from Casper Wyoming the bike ran great. Sunday morning she was a sputterin' and a spitting, missin' a bit. At first i figured with the humidity being high maybe my fuel picked up some moisture, or maybe air filter was damp.
    Fueled in Franklin, fresh gasoline. Oil: fine. But she still missed and sputtered. At highway speeds she did fine, however when I'd come into town, she would sputter and die out. Thought maybe my NEW petcocks a factor and played with them to no avail (plus I get to say, "No avail"). Then each town, it would sputter, die out then argue when I'd start her. But once she did start and added a bit acceleration she'd be okay while I got unto the highway. When in Scottsbluff, I pulled the fuel bowl to check debris: both okay. The fuel lines: clean and clear.
    In Casper, Wyoming (Home) she would still sputter, and put a light blue flame from the pipes.
    Are my cars, now too rich? Anyother diagnostic time savers (from the vetran tinkerers)?

    BTW, if you want more info on Wyoming, I'd be pleased to let you know a few things.
    Michael A. Bailey
    aka Scharppslicer
    aka SwordofWords in some circles
    Casper, Wyoming
    K100LT ('87)
    80RT ('83: re-rescued from someone who let her sit for over 3 years)
    R69 (58: Not for Sale)

  11. #11
    Registered User ebeeby's Avatar
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    80RT Missing

    I can tell you what just happened to me. Did a Dallas-Colorado-Dallas trip on R75/5. Did a long hot brutal 600 mile first day. 300 the next. When I got to Denver was very very hard to start. Wouldn't idle. Had to crack the throttle. Figured it was the altitude, water in gas, bad plugs, etc etc. After eliminating all those I did a valve lash adjustment. Both exhaust valves were tight. (see seperate thread). When both exhaust valves are tight, there is not enough compression to start let alone idle. Upon making the adjustment (my intakes were a hair loose) the bike started extremely easily and ran fine. It had seemed to run fine at higher rpm before, but at a loss of power - again I attributed to altitude.

    Sounds like your long ride may have done the same thing. Easy thing to check and correct though it may indicate other issues like valve recession. Re-set the valve lash and check it again in 1000-1500 miles to see if they've gone tight again.

    Eric
    1973 R75/5

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