has anyone done the low beam headlight relay mod on an NC35? seems to be little info for rvf's, do i need to get access to the wiring under the tank?

cheers

It's the same as the nc30, the wiring colours may differ though.

Yes, I have, and no, you don't need to take the tank off. You just need plenty of nice, heavy grade multicore vehicle cable, a fuseholder with 30A fuse, a 30A normally open relay, two ring terminals for the battery, and four female spade connectors to attach the wires to the relay. Some heatshrink tube to neaten the joins helps, and if you really want to be a tart, a few inches of that rubbery insulation tube stuff to neaten all the wires around the relay. I did mine slightly differently to the method that was written up somewhere in the docs section, in the same manner in which Neo or Magg did it (I cannot remember which it was now!). To keep the weather away from the relay, I mounted it next to the high beam one. OK, I gaffa taped it to it... Anyway, here's how I did it. I would advise making yourself thoroughly familiar with all the bits before actually committing the cable cutters to anything!

The relay has four poles, numbered 30, 85, 86, and 87. The new feed from battery goes to 30, and the output to the lights comes from 87. 85 and 86 are used to close the relay, so one is connected to ground/earth, and the other is connected to the switch. You use the output of the existing switch to switch the relay. The relay then takes the load rather than the switchgear, so the contacts don't die. But then you knew that anyway As I mentioned earlier, I located the relay with the high beam one as it seemed the most sensible place to put it.

Positive feed: I started by soldering a battery type ring terminal to one end of the inline fuseholder. I then ran a length of 30A red cable from the battery box area to the headlights, following the route of the main wiring loom. This is then soldered to the other end of the fuseholder, then the other end trimmed to length and a spade connector soldered to it. The spade is them pressed onto pin 30 of the relay.

Earth: to ground the relay, I used some black 30A cable (this is probably overkill) with a spade on one end, and I spliced it into one of the earth wires for the headlamps (green). If you don't want to do this, you could run the earth back to the frame earth point, one of the coil brackets, or even the negative terminal on the battery. The spade goes to pin 85 or 86 on the relay.

Switch: the bit you've been dreading, cutting the switch output. The switch feeds the low beam filaments via the white wire. So, to switch the relay, you need to cut the white wire between the point it exits the switch and where it feeds the headlights. You then need to get some cable (again it doesn't need to be 30A for this) and solder a spade on one end for pin 85 or 86, and solder the other end to the wire that formerly went to the headlights.

Headlamp power: the last connection goes to the headlamps. Each headlamp connector has a white wire coming out that was originally connected back to the handlebar switch. These need to be joined to pin 87 on the relay. Or, ideally, the white wire needs replacing with some nice new 30A stuff if you can get the bits out of the socket. If not, the less white wire you have, the less power you will lose due to the extra resistance. The absolute easiest manner to do this would be to solder a new 30A wire to the free end of the white wire which is still connected to both headlamp connectors. However, this means that there is plenty of white wire between the headlamps and the relay, which will result in a small loss of power. In my case, I had replaced one of the connectors a while ago, and the new one had heavier wire, albeit still connected to the white wire. So, I replaced the other one, as well, which meant dispensing with the white wire altogether, save for the feed to the relay. As I used the white wire from the right headlamp to switch the relay, this left the left side requiring capping off as it is still connected to the handlebar switch. Depends on which route you take...

I would recommend replacing the headlamp connectors if you have the time, or if it's not possible to replace the white wire on them with something heavier.

Ironically, I still haven't got around to fitting the 60/55 Nightbreakers yet... lol

speedy231278 wrote:Ironically, I still haven't got around to fitting the 60/55 Nightbreakers yet... lol

Get them in! Makes a world of difference

Thanks speedy thats brilliant, very useful

I have just picked up a fused 20A relay, will this do the job?

Yeah 20a is fine, it's what I'm using on my nc30

yeah thats what i thought, will it being fused make any difference? (i.e. not work?). Sorry I am clueless when it comes to electrics!

Being fused is OK (unless you blow the fuse and therefore need to rip the relay out to change it.. lol). Now, depending on where the fuse is (I assume it's across the switched contacts) it may well remove the need for you to fuse the spur from the positive terminal of the battery. 20A is fine, as BM says. In theory, your two 55W low beams are drawing 110W/12V= approx 9A. If you want to argue that at 5K you're producing 13.5V at the battery then 110W/13.5V= approx 8A. This is probably a little simplistic since there is usually more to Watts=Volts x Amps than meets the eye with this sort of stuff.

The fuse in the relay stops you switching more current than it can handle. I don't see why it wouldn't protect the spur as well, although I guess you could argue that if the spade dropped off the relay and found something to ground with, you'd get full battery power stuffed into whatever it found. On second thoughts, fusing it at source suddenly sounds more inviting!