/5 ignition switch ?'s

[Unclviny]

1973 1/2 R75/5 it was that "magic moment" yesterday, the weather was great and with the NFL on TV the roads were clear so I went out for some "/5 therapy".

I stopped for a bit and on getting back on the road I put the key in and the headlight came on but none of the indicator lights did, the key just freewheeled around (there was no lights and ignition position) and when I pulled it out the headlight stayed on. But it seemed to "heal itself". Is my switch hosed? How do I proceed?

Vince

[Jean]

There is a very good "How-to" on Duanes site about fixing a /5 switch. I think the site address is w6rec.com/duane/BMW/ . Not sure about the front slash at the end...and that's a www/ in front, BTW.
It's got some good pictures.
Read THAT. Better than trying to tell in words.
Also...follow any advice to operate the switch carefully; apparently there are many ham-fisted folks who have bugered them royally.

[Deleted User 62]

Vince, you need to pop the headlight off and look at the switch board and contact plate above it. First of all, the headlight shouldn't come on when you push the switch down, only when you twist it counter clockwise. This would indicate that the contact plate is stuck in the wrong place. The contact plate has a small U shaped divit that should be pointed towards the front of the bike. The fact that your key spins with no effect means the mechanism that holds the key and moves the contact plate isn't working. There is a spring and a couple ball bearings in there that hold the key in place. Look above the switch board and you should see the contact plate rotate when you turn the switch. If not, that's the problem. Unfortunately, you'll need to remove the switch board to address this. Also, when you press the key down, there is a spring loaded contact on the bottom front of the switch board that should be bent down and touch, like a set of points. That's what turns the ignition lights on. The lower tab can be bent up slightly to make better contact.

[Jean]

Well, there you have it in words.
Unfortunately the little tabs that hold the switch board in position are really easy to break-off. There are some spares but they might have already been used. In that case, BE CAREFUL what you do in there.

[Deleted User 62]

Found this photo on the web: You can see the divit in the contact plate just below the brown wire, and the contact points directly below it and the switch board. Jean is right, fixing it correctly requires removing the switch board and the possibility of breaking one or more of the tabs that hold it on. OR... you could leave it the way it is, and just bend up the contact so the ignition works (or clean the contact points if it seems to be touching) and add a switch to turn off power to the headlight.... More useful information here: http://cmtk3.webring.org/l/rd?ring=bmwb ... Findex.htm

[Motorhead]

MY BEST first!!!.............. was replace that switch with a keyed switch

a stock german BMW key switch fit's under the chrome cover even a aftermarket 3 way

the off an on german needs a switch to control light (and you can match all keyed and make your bike 1 key like mine)

the after market you don't need to add switch as the lighting switch is already in the switch


run off light/run

[Jean]

Tim, that is a beautiful picture. I'm gonna print IT for my notebook. It is a lot better than the one included in the instructions I mentioned earlier!

[Deleted User 62]

I wouldn't take that photo as gospel for rewiring a headlight bucket. Note the extra wires and blue crimp on add-a-connectors... Found this on the web too, a how to for adding an aftermarket switch: http://beemersandbits.com/2011/05/bmw-5 ... -retrofit/ Just a thought, you could mount the key so that it points straight ahead when in the "on" position. So much more aerodynamic...

[Jean]

I'd bet most /5's have had some wiring worked-on by now.
I DID notice the splices.
the link about the switch-key shows the little tabs and the switch plate very good too!

[wookie]

Ditto Jean. When I worked at the Beemer dealership in Austin in the 90's, we saw scads of /5's that had been passed down from student to student. The wiring was usually a snarl of mis-match and many of the fasteners were, shall we say, not factory approved.