hmmm Brake switches .....

some long time ago i bought some switches out of great Britain  in the hope of replacing the bmw brake switch part , which for this old pensioner is horribly expensive at $55 + delivery etc. these days . so a solution for a cheaper option was sought .

just now i have exhausted my stock of good working replacements , and i have still an issue on old Gerty , with the foot brake switch with a shortened action which is just confusing for the following rider i guess .
basically the switch plunger plastic section is now particularly short , meaning any slight pressure activates the brake lamps , either by accident or even pothole bashing .
so finally i have had to resort to attempting to use these switches i bought, way back when .

a main issue is that the replacements are threaded with something like a 6mm thread 
the bmw switches are 8mm x 1.0 pitch 

thankfully  Murray  a local member here (redrock mania ) came to the rescue with some technical help as he had the tools , lathe etc  that i didnt have at hand , although i had planned to use the resources at the mens shed  where i volunteer my help a couple of days a week .

anyhow we got discussing the idea and murray took the sample parts away with him and came up with a result .

my thoughts were to make a threaded sleave acting as an adaptor between the two different threads 

Murray tried brass as the adaption piece without success as the brass couldnt really support the strength reguired in its wall thickness  , but another attempt proved that mid steel would do the job.

since making an adaptor that kind of fits Murray has discovered that the switch thread is likely an imperial 1/4 inch x 32 tpi  rather than 6mm x 0.75 pitch .
but in any case he has screwed the latter onto the switch leaving a possible fix for the initial issue of the foot brake operation.

Murray has ordered a suitable tap to make the switch to adaptor thread a complete success for future use 
so we will see the outcome in the not too distant future .

whats left to do now ?

make a Mould for some silicon to cover the electrical connections at the back of the switch - cable 
or 
just use some glue lined dual wall heat shrink for that purpose , (which i have used extensivly on just about everything motorbike related , which certainly keeps the crap out of entering and is still flexible enough to make life easy , rather than the hard setting single layer heat shrink that we mostly know and is more commonly available. ) 

some pics ?

i guess this will explain it all, mostly,

with many thanks to Murray for spending the time and effort in this endeavor. 

Recently I found something affordable in these United States:

New MAGURA Brake Light Switch Normally Closed NC Circuit 285.55 Gray tip M8x1.0



$14.00/ea and there are 4 remaining at this eBay link as of today:



https://www.ebay.com/itm/155174986760

Great find Bricklayer ,  that works out about $22.00 each + freight etc , if they ship overseas 

cant find the same thing locally ...yet 

thanks for the link , appreciated greatly

i guess this will work. 

with the dual wall heat shrink i used (shrinks x 4 times its original size )

if this works out ok , ill have to finally connect one up to the choke indicator circuit as well ...its been a verry long time without one there  ....lol 
poor old GERTY .. SIGH !
About $10 aus for this.

Further to Charlie's Post #1, I am now up to my 3rd attempt to make a threaded adapter sleeve to fit the smaller diameter microswitch to the M8 x 1.0 Magura switch thread. The adaption involves making a metal sleeve threaded on both the inside and outside. I can confirm the inside sleeve tap thread size is 1/4 - 32 and the outside uses a M8 x 1.0 die. The sleeve is quite difficult to make because the sleeve wall ends up very thin. The sleeve tube only has a 1mm thick wall BEFORE threads are cut on each side. My first attempt using brass saw the brass collapse as I was cutting the second thread.
2nd attempt: I machined a sleeve out of steel using a M6 x 0.75 tap for the internal thread. Wrong tap size: the sleeve began to bind on the external microswitch thread before fully fitted.
3rd attempt: Machined a steel sleeve. Cut internal thread with 1/4 - 32 tap. Cut external thread with M8 x 1.0 die. Due to the thin wall the sleeve began to distort a little when cutting the second (external) thread. Solution: Ran the tap up the internal thread (providing wall structural integrity) and left it in place before cutting the external M8 x 1.0 thread. 
Cutting the thin threaded sleeve to length: Measure the length of cut thread only on the Magura switch then cut your sleeve to that length. Do not include the short unthreaded section in your measurement. Be very careful when cutting the sleeve to length because it can easily deform. 
The alternative switches are very cheap out of China. I purchased 10 for less than $A2.00 each. You can afford to experiment.

Try putting an external thread on a Nutsert rivet. 
Regards Martin.

I've just embarked on this very mod when I found this Thread. I looked at the Magura switch but their nearly $50 landed in Australia. I bought the Cheaper one from AliExpress, $7 for 2.
I used my hobby lathe to make an M10 X 1.00 outer thread X M6 x 0.75 inner thread reducer. 7mm in length. As Charlie said the switch is likely imperial but I just ran an M6 X 0.75 die over it and that worked fine. I taped out the pedal plate and Loctite the adapter in place. The switch screws in to just the right length. I also used glue lined heat shrink, I got that from Jaycar.

Tidy!

great result .

BMW Part #: 61 311 459 569 is the original Front and Rear brake light switch. It has a M8 x 1.0 thread for fitting to the rear brake pedal or the front brake lever housing. Post 7 [Gravelsandwich - thank you] provides an elegant solution for replacing the rear switch with a generic switch modification. Drilling out then tapping the rear brake pedal to a M10 x 1.0 thread permits the fitting of an AliExpress switch  (see my post 5) by machining a thicker threaded sleeve. Because the rear switch can be enlarged to M10 x 1.0 the added thickness of the sleeve [ID to OD measurement] makes the task of sleeve making much easier and more robust - see my notes on M8 OD sleeves collapsing due to wafer thin walls. I have carefully measured the thread pitch of the AliExpress switches and it is not M6 x 0.75 - it is 1/4 -32. There is very little difference between the 2 but it is there. I looked at increasing the M8 x 1.0 to M10 in the front brake lever housing, but it seems too risky.  gives a great solution for  fitting a modified rear brake switch.

Thanks! The reason I used an M10 thread is because a previous owner had already drilled out the pedal 8mm to fit an aftermarket non threaded switch and it was just sort off pressed in. An M9 would have worked but I didn't have one, but I didn't have any trouble cutting the sleeve, M10 with the M6 inner. The switch I used after the thread is slightly bigger then the pedal hole and fits snug when screwed in. Be interesting to see how long it lasts.