because my brake light switch does not really work during city cruising due to a lack of fluid pressure for the switch at sensitive braking I was looking for an alternative and read some quite interesting threads here showing the same problem and also some nice solutions.
However I did not like to drill holes into my Atom like in the brake pedal or the mounting brackets of the 3 pedals.
So the only option I found was to use the two holes on the upper side of the mounting brackets for the pedals.
In the following I would like to share what I have done.. So perhaps it may be of help for somebody like I also already found a lot of help here
One thing in advance:
I have not tried but this version may not be an option for those who are permanently using the brake bias by more than just a view clicks. It is fine for „normal“ adjusting, but otherwise you would probably have to readjust the switch cam as well, which could be done in a minute, but you at least would have to stop and get out.
In every case if not already done you should do a proper brake bias adjustment in advance of adjusting the switch cam.
Parts needed:
- Microswitch, make Highly, Omron, Crouzet or similar (do not take the cheapest ones), incl. lever, min. 10A @ 250VAC
- piece of 2mm aluminium 82x100mm
- piece of 10mm aluminium 35x15mm
- 2pcs screw UNC 1/4 x 1 and spring washer, stainless
- 2pcs screw M3 and nuts, stainless
- 2pcs screw Allen key M4x16mm and spring washer, stainless
- cable 0,75mm, length about 40cm for two-core cable or 80cm in total.
- connectors 2pcs male, 2pcs female, 2pcs cable crimp connector
- heat shrink tube
Tools needed, apart from what probably everybody finds somewhere at home:
Soldering iron, drilling machine, PUK saw or better a mechanical fret saw, bench vice, M4 screw tap, a rough and a fine file
The mentioned switches are not waterproof and I drilled some holes into the bottom side for draining just in case. Also I removed the not needed closing contact, which leads to a bigger distance between the opening contacts. So Water should „only" be a corrosion issue if at all. In general this would not be necessary I guess.
If you prefer a waterresistant one, the only one I could find by reasonable search was a honeywell V15W type.
If you intend to use a different switch make sure you order one that connects when opening.
Because my Highly microswitch is specified for 10A @ 250VAC and I read, that I cannot compare AC with DC I checked the switch with 5A @ 12V, which is the actual approx. current for the Atom brake lights (measured). I checked half an hour with constant current and half an hour playing disco. The switch was fine, no temperature or other issues. So not sure, whether this might be a representative test, but good enough for me to give it a go.
The drawing shows the aluminium mounting sheet from the buttom for the case you are using a scribing iron and you may not want to have the scratches visible on the upper side.
I splitted the original cable coming from the pressure switch (not from the main harness) and added two cables with connectors.
I am using crimp connectors. As I do not own a crimping tool I use old not sharp side cutting pliers.
The original pressure switch is still in use and works parallel with the microswitch. I did that just in case, that my construction would fail, so I would still have the standard option. Nevertheless the adjustable microswitch connects a lot earlier than the original pressure switch.
I cut the lever of the switch to the length of the microswitch to not have it visible next to the aluminium sheet.
Probably you could also use a switch without a lever, but as the aluminium is more rough than the stainless lever the plastic of the microswitch may last longer (if end of switch life would be reachable at all).
The measures shown in my drawing are in general for my Atom only. Especially the length of the slimmer 40mm part of the aluminium sheet might deviate due to a different adjustment of the brake cylinder push rod at other Atoms.
Cut the screws fixing the switch shortly right below the nut and use a Loctite or a bit superglue to lock the nuts. I did not use locknuts because they are about 2mm longer than standard ones and I wanted to have that space here.
Instruction:
1. saw the aluminium sheet
2. drill the holes; the holes for the microswitch are for V3 switches, so the hole orientation is diagonally. The second hole for the microswitch should be drilled using the switch as sample
3. bend the sheet. That must not be too precisely regarding the bends themselves, but in the end the height should be quite correct.
4. solder the cable to the microswitch (and for opener/closer switches use the correct contacts, you would not be the first to have it all assembled to the Atom and finding out you soldered the microswitch as a closer instead an opener
)5. assemble the microswitch to the aluminium sheet
6. fix the cable with a strap using the little holes next to the sheet mounting hole. Protect the cable against the strap using heat shrink tube e.g.
7. remove the upper dash panel (this exeptionally belongs to the Atom
)8. assemble the switch cam to the brake cylinder push rod, do not yet tighten
9. assemble the aluminium sheet to the pedal mounting brackets. Do not be too disappointed if you now have to correct the bending. Take into account that the push rod also moves up a bit.
10. adjust the switch cam
11. connect the cables. You may have to cut and replace some straps for that. In case of doubts use e.g. heat shrink tube around the straps to prevent damaging the cables. Some straps are quite sharp-edged.
practical testing to start end of this week
pictures to follow, cannot upload them at present...