MK 1 switch gear...expert required....

[PhilGreaves]

Hi everyone,

Well as the title implies really I’ve got a highly technical question. I’ll try to be brief though.
Some of you may remember from the icccr that my main/full beam light switch (left hand block) went from working intermittently to not working at all. I got told it was ‘contacts’.

So yesterday I decided to have a bash at least cleaning the contacts so it may work for the mot. I know a stupid temporary fix but I don’t drive the BX at night nor am I selling the car so I really couldn’t care less if main beam works. I mean how often can you use it now?
Anyway after hours of fiddling and analysing every component I’d stripped the switch (4D) right back, probably further than you’re meant to! Eventually I figured out that it was the plunger* that wasn’t lubricated.

At the same time as doing this I stripped down my nos unlabelled right hand unit thinking id know how to put it back together. Upon stripping this down I found that the switch was still the correct way round for fitting into the left hand unit. However it is labelled 6C.

Question then is: are they (4D and 6C) interchangeable

I didn’t try, partly because I got 4D working and partly because I thought 6C was labelled ‘L’ for ‘live’ where the other was labelled ‘E’ for earth. I have to admit it took me a while to work out that it was unlikely that a German made component for a French car was unlikely to use ‘L’ for live……and it may be an ‘r’ anyway.

So the switches then:
a) 1984 16 TRS switch 4D. Contains plastic cog, square and copper arm.
b) Unspecified base model unknown year, switch 6C. Contains plastic moulded lump with no other moving parts and very little movement.

Is it possible, given the less moving parts and that it’s unlikely to be earlier that 1984, that 6C from the nos part is simply a later, more reliable version? In any event it would be useful to know for future reference if they are interchangeable.

Also, bonus question , the spring in the light unit was actually missing, so I had to borrow one from the nos right hand unit. If the existing right hand unit spring breaks then I’ll be stuck. So as the spring only resets the plastic facia is it necessary for it to be made out of copper Again no hurry but would be useful to know.

The copper spring is located in a black plastic alcove on the side of the switch mechanism and is (rather annoyingly) smaller than the papermate pen spring..
Hopefully someone will know what I’m on about!

Thanks in advance,

Phil
*sorry no idea what else you should call it! Lubricate with 3 in 1 and wd40 to get it working again/prevent it failing.

[Tim Leech]

I have a spare one Phil I am sure, think it may be new if that helps.

[Mothman]

i might have one as well, what colour do you need?

Andy

[Tim Leech]

Grey!

[B-Hive]

Maybe its the blonde hair, but I kinda got lost in yr description of whats going on...I have had the pleasure of fully pulling apart these switches..and by the looks of things in the TRS I am heading for it again..

The biggest issue I have found is that these switches get hot.. and so the little plastic cam/actuator tends to melt enough for the toggle not to work..

The switches can be refurbished by mean of gentle reshaping of the flat spots on the actuators,, they will end up feeling slightly less positive in their action but should work none the less..oh and btw the colour caps can be swapped out for matching if required..

However it seems like you have replacement options from the guys here...erm slightly different story down under where Bx parts (especially especially MK1) are more rare than the proverbial wooden horse poo..

My TRS headlight dip switch (permanently on high beam) is coming out tonight.. for a look see..I've Just gotta remember that there's a teeny weeny spring that likes to jump for freedom and hide...Thinking thats what happened to the spring in yr switch ..they dont work at all well without them,, so it probably jumped out without you seeing it...

Any way Good luck