Wiring harness musings

This is an excellent thread! To the soldering posts, I'd add the advice to flux, tin, and use enough heat.

For the uninitiated, flux is basically a mild acid that strips surface contamination off the wire and slightly etches it so that the solder will stick. I agree with 1974jh5 about rosin-core wire, but it's always helpful to have a little pot of paste flux and an acid brush handy. I really appreciate flux when soldering terminals, old/dirty/oily wire, throttle cables, etc. A proper flux job will go a long way towards letting the solder flow instead of bead up and roll off the metal.

To use the flux, just dab a tiny amount on the wire and/or terminal, then heat with a touch of the soldering iron until it melts and flows. Don't burn it! If it goes black and bubbly, it'll just be adding more contamination, not removing it. Use just enough to do the job; if there's any semi-liquid residue dripping, you've gone too far, and it should be cleaned off.

Tinning is just applying a thin surface layer of solder to the separate parts before soldering them together. Tinned wires and parts are a little quicker to solder, as you don't need to fill the wire up with material or fight to put enough heat in. You just have to add an extra dab, or re-melt the tinning and let the parts flow together.

I feel that the two things that most frustrate people who have a hard time soldering are dirty surfaces (failure to properly flux, be it with paste or rosin-core wire), and using too little heat. Ever heat a wire and have the solder barely melt, while the insulation on the wire softens, shrinks, or smokes? The wire is pulling the heat away from the solder joint faster than you can put it in. A more powerful iron gets the heat into the solder fast, before the wire can pull the heat away.

I use a Weller WESD51 station, set to 575 degrees for this sort of general small-ga wiring. I was reluctant to spend the money on one, but I tell ya, the first time you use a decent 50+ watt station, you'll wonder how you ever did without.

i made my own solder station,with a light dimmer, i don't have a fancy display but you get the feel for it were to put it.

when i solder wire togeather i put a bit of ele.tape then put on heat shrink,why? some times the solder leaves pointy thorns, that might pop out of shrink tube and short out

Fantastic thread. Thanks!
A question: how do you properly use this type of crimping tool. (this pic is from that link to the site that has Japanese style connectors) I believe this is very similar to the one Mikes sells. I've not been able to figure out how to use it with bullet connectors. I mean I can get it to sort of crush the thing, but usually only one tab will close and I'l have to do it a 2nd time to get both to wrap around. I finally end up just using my el cheapo crimp tool. But there MUST be a way to use this thing that I'm just not understanding. If anyone wants to tackle a detailed (and preferably illustrated) instruction on its use, I'd be very appreciative. TIA!
http://vintageconnections.com/images/10-Inch-Tool-s.jpg

That looks very similar to the ratcheting crimper that the Weatherpak people sell to use with their terminals. Notice the curved shape of the crimp jaws? That's so the crimper will 'curl' the tabs as it closes. The one pictured above has flat jaws, it can't curl the tabs, ony squash them.




It has to close all the way for it to crimp properly, it's designed for use only with their terminals and once you start squeezing the handles the ratchet won't let it open till you complete the whole cycle. If it's used with any other type of terminal it won't work properly. Not sure if that's the deal but you might look into it.

osteoderm brought up a good point about wire corrosion making solder not stick. For some reason (I think it's the alloy) automotive and motorcycle wire of the 1970's will have a black corrosion on them. I can't find a pic, but it's easy to spot: when you strip the wire the strands will look like they have flat black paint on them. That stuff is a real bitch to remove and solder absolutely will not stick to it. Flux doesn't seemt to affect it either.

In the past when I have run across this stuff, I have cleaned the wire with acetone and a rag, then used brake cleaner etc. The wire will have a dull look to it once it's removed and now you can solder it, but the wire will be brittle. I recommend save yourself a lot of future aggravation and just replace the wire.

That crimper has different jaw sets for different type terminals-its the one Vintage Connections sells.

John

Installing the Mike's terminals with solder:

You'll notice there are two sizes of tab. The small tabs are crimped to the wire, the large ones go around the insulation. These were originally designed to be crimped only, but I prefer to solder them.



Strip the wire so that there's enough to go in the small tabs but the big ones will go around the insulation. Then you 'tin' the end of the wire. All that is is touching the iron to the tip of the wire then the solder so that the end of the wire is coate with solder. This takes about 2 seconds if the iron's hot enough. It should look like this:



Lay the tinned tip of the wire in the small tabs, then crimp them onto the solder. This can be done with a crimp tool or I have had good success with needle nose pliers. Once the tabs are crimped down, hook hemostats to one of the big tabs to act as a heat sink. That keeps soldering heat from melting the insulation.

Now touch the hot iron to the small tabs, and watch the solder on the wire carefully. Once you see it melt and flow onto the terminal, take the heat off and wait for it to cool. Remove the hemostats and crimp the big tabs, then slide the silicone insulator boot into place. If you are installing the female side, it works best if you slide the silicone boot up the wire. It can be installed over the terminal after it's soldered but it's easier if you put it over the wire first. The male terminal boot can be installed easily either way.

Wire amperage capacity is dependent on the length of the wire and the gauge. On this chart, it's easy to see just about everything on an XS can be wired with 18 ga safely, with 16 and 14 used for some of the higher capacity circuits.

What's so important about ground connections?

Electric circuits can be thought of much like plumbing; the water comes from the big tank (battery) through pipes (wires) then through faucets (switches) through the sink, dishwasher, etc (motor, bulb, etc) then through the drain into another pipe (wiring). The big difference is that when the electricity goes through the drain it must be able to return to the battery via the negative terminal or the circuit is 'open'.

The ground handles the amperage which remains after the load has converted part of the power in into work and heat. That means it is important for the ground circuit connections to be every bit as clean and tight as the power in side. In fact it's more important particularly with solid state electronics.

In the interest of saving money and cutting down complexity, manufacturers use the metal frame of their vehicle as part of the ground circuit. This works great unless the ground points get corroded, loose or are not connected. Electricity wants real bad to get back to the battery and if the good ground path is missing it will take any secondary path it can. This can lead to really weird things.

Back in the 1980's Chrysler had a tech bulletin which addressed premature transmission and wheel bearing failure in some of the front wheel drive cars. It seems the alternator was grounded to the engine which then was grounded to the body via a short flex cable. If the flex cable failed, then the power generated by the alternator took all kinds of tortured paths to get back to the battery. This led to the electricity traveling through the transmission casing to the inner CV joint then down the axle to the outer CV joint then through the wheel bearings to the strut and then to the body of the car. The wheel bearings had small burnt black spots, looked like pepper. That was from the thousands of tiny arcs inside the bearing as it turned. In addition, sometimes the inside of the transmission case had a mottled look. This was because the transmission became a very primitive plating tank, metal from bushings etc was deposited on the inside of the transmission case.

I saw a Pinto which had melted the heater control cables. Turned out the owner had installed a battery with the terminals in the wrong place; to make it fit he disconnected the center loop of the ground cable. Now the only way the lights, radio, etc could ground to the body of the car was through the heater cables and they got red hot.

On control units like TCI's etc, poor grounds can lead to all kinds of weirdness. These modules depend on proper voltage signals because in the final analysis that's all they do: compare a input voltage signal from a sensor to whatever's stored in the chip's programming parameters and do whatever is supposed to be done. For instance, the TCI uses the signal from the secondary pickup to decide when to advance the ignition timing. No signal or the signal never gets to the predetermined voltage to trigger the advance point = no advance. So the engine might be running 6000 RPM but no advance. You feel this as no power and the engine overheats due to retarded ignition timing. If the TCI is not grounded properly, the full voltage signal can't make its way back to the battery so it has not the foggiest idea of what to do.

Too many times I have seen stuff reassembled with ground wires just dangling because 'nahh, it's not really important.' Nothing could be further from the truth. So the ground connections should be done every bit as carefully as the power; clean tight terminals and if you paint the frame the paint should be scraped or sanded away from the ground points before the bolt is installed.

Actually DC power (Current ) flows from Negative to Positive not the other way around unless it a AC power source ( AC tries so hard to be DC but it can't ) ... That's why when you work on something DC ( i.e. a car, truck, motorcycle ) the directions always tell you to remove the negative terminal from the battery...

this is a great resource. Thank you.

What about "T" connections? I'm about to start wiring up my simple hardtail project, from scratch. I ordered a small single power-in, 6 fused power-out terminal in effort to further simplify my project's wiring harness and also partly because I want to reduce the number of 'T's from the main power supply wire. And, I have not seen a clean enough "T" solution to satisfy my OCD tendencies. Even with the fuse block, though, there's still a need for a few "T''s. If anyone can point me in the most pro-looking-ultra-clean-T-connection direction, I'll probably stick with "T's and ditch the fuse block, as I don't exactly have a place to hide the automotive looking gang box.

Is running two wires into one end of a butt/bullet/spade connector/solder into the middle of an existing wire the best way to create a 'T'? Is there something obvious that I'm missing, or is really that simple? Photos would be awesome.

trying to weigh my options. Thanks for the help,
avenue.

Do you have a repair manual? The Clymer book has a section that talks about wiring repairs. There are several ways to make good tee connections, none use crimp connectors.
Leo

yes, sir. The clymer manual T connections are still ugly, though, imo. I ended up using their T method to make 'Y's, then heatshrinked the two legs together for a cleaner looking split before the two wires go their separate ways. Probably what everyone's T's end up looking like, anyway.

Is this what you are referring to as a 'T splice'?



It's done the same as a soldered splice, shrink wrap the same way.

that's exactly it. the good looking way, that is. among other things, unkept wiring bugs me to no end.

Just to throw this out there, but does anyone have any thoughts on the Posi-lock brand of products?

Do you want it to look good or work good?
Leo

I know I'd sacrifice looks for functionality, I hate electrical gremlins.

One of the best electrical threads I've ever read, my hat is off to you sir.

On a side note, how much do you charge to build a brand new wiring harness for my XS? It would make my life easier!

I'm off to eBay now to buy a nice solder gun and some wiring paraphernalia

about connectors:
once I used JST connectors from namz
http://www.namzcustomcycleproducts.com/products/electrical_connectors.html#top
they also have other models of connectors - you choose.

and other source of different types of connectors is Eastern Beaver
http://www.easternbeaver.com/index.html