Ironhead THE Wiring Harness Routing Thread

dsk1000 · #1 14th June 2012

Hey guys,

Wire routing has been a nebulous topic here. I've read all the threads about wiring harnesses I could find. In a number of them, some folks talk about running their main wiring harness through the backbone of the frame using the stock holes, entering at the front right side of the frame and through the rear near the circuit breakers.

I'd love to hear from someone who's actually done this or seen it done. Specifically, I'd like to know how they run the key and horn drops if the harness is inside the frame, with no holes mid-frame where they need to be.

Also, it's not clear to me which method was stock. I would lean toward assuming running outside the frame was stock. Anyone know or have documentation of this? My year is 1975 but I'm sure info relevant to all years would be helpful to the group.

The pragmatist in me says running the wiring through the frame could make it that much harded to fix any problems that arise and subject it to chafing from vibration. Maybe that's overly cautious. I'd love your thoughts on that too.

It could make a valuable sticky if we could sort the wire routing info out once and for all and would be willing to work up some diagrams/graphics if we can reach a credible consensus.

Thanks, Doug

piniongear · #2 14th June 2012

You can expect to receive several different answers to your question, and all may be correct.
What I am saying is that it depends on what year model you have.
1972 and earlier have the hole in the front right side of the frame member and an open tube at the other end of the member.

The 1973 and later frame was changed and the casting under the seat was replaced by a welded steel strap.
What this strap did was seal off the end of the top tube and seal off both of the vertical frame tubes where the supports for the old solo seat were located.
If you have the later model frame you may find the hole still in the right side of the frame top tube but the other end should not have an open tube showing.
In this case you will have to run your wiring outside the frame unless you want to drill/cut a 1 inch hole in the end of the top tube (under the seat).

Here is a pic of my wiring going into the top right hole on my 1971 XLCH..................................

You can see the shrink wiring bundle entering the hole on the right side of the pic.
The wiring is run inside the top tube and exits at the rear under the seat.

After exit of the frame tube, these wires connect to a small panel board (4 or 5 connections) and from the panel board the wires are run to the horn and other places that are required on an XLCH and XLH.

These models are different, with the largest difference being the CH is kick start only while the XLH is electric (or electric and kick).
1972 and earlier came from the factory with this wire routing.
pg

dsk1000 · #3 14th June 2012

Thank you. My 75 does have a hole in the rear of the backbone. I ran a wire just to see if I could do it. There does seem to be a "hump" somewhere inside the backbone, but I got over it by running a fish wire from the rear.

I suppose then that running everything back to the terminal area would require me to rebuld the wiring harness, or at least the wires related to the horn and key, and then extend them back forward to where they need to be.

piniongear · #4 14th June 2012

Quote:

Originally Posted by dsk1000

Thank you. My 75 does have a hole in the rear of the backbone. I ran a wire just to see if I could do it. There does seem to be a "hump" somewhere inside the backbone, but I got over it by running a fish wire from the rear.

I suppose then that running everything back to the terminal area would require me to rebuld the wiring harness, or at least the wires related to the horn and key, and then extend them back forward to where they need to be.

Correct.
That is one of the problems using a purchased wiring harness rather than building your own harness. There are plus and minus issues to both ways.

As I see it, your horn and key wires terminate at the horn & switch location using this harness.
This works fine for routing the wire outside the frame tube.

If you want to route inside the frame tube you will have to connect on to the horn and switch wire(s) and extend them back to the control panel, then run them forward to the horn and switch.
If you choose to do this I suggest you solder the connections and then cover those connections with shrink tube. That way you will never have a grounding problem and can forget it.

But you may be better off to use the harness as it was designed for (outside the frame tube). Most of it will be hidden by the fuel tank anyway.
One of those things where you have to make your choice.
pg