Grounding location

I am installing a new wiring harness in my 69S and am unsure of the ground location of the red wires that are grouped with the coil/points wires. I thought that they went to the central bolt of the head steady but the ring terminals are too small to accomodate the socket head bolts. Are the ring terminals incorrect or do they connect elsewhere? The only other place I can come up with, given the length of the wires, is on the tabs that the condensers attach to as the ring connectors would fit the screw diameter.
As always, your help is GREATLY appreciated.

Tom

I'm not personally familiar with the olderCommandos, but you could connect the ground to the frame tab, then run an additional wire from that point to the engine (make one up with the appropriate terminals). You always want a solid, continuous ground from the engine power unit to the main frame or a WELDED tab.

I don't think they connect to the tabs where the small capacitors connect. Here is a picture of mine upon starting diss-assembly and the red wires are already disconnected. They are not connected to the capacitor tabx, but are loose. So I am saying I really don't know where they went, but it would be good to eventually get a good connection to the engine. Maybe someone else can enlighten us, I need to know too.



Dave
69S

There are a couple of photos in the Haynes Commando manual (pages 15 & 49) which shows two earth/ground (presumably?) wires going to what looks like a sleeved ring terminal fixed by a nut and bolt where there appears to be an empty hole in the rear of the upper face of the coil 'L' bracket shown in your photo?

The critical ground points include:

Engine (power unit / case)
Battery
Coil mount & grounding connection
Ignition grounding connection
Frame (if items attached to it will depend on it for a grounding path)

Anywhere you intend for a reliable grounding circuit to exist, you must consider that electricity passes through a weld better than a bolted connection, and it travels better through a prepared, bare bolted connection than one that has been painted or ESPECIALLY powdercoated. Even thought holes for bolted connections may be bare, the surrounding metal must be bare to insure a good connection / path to ground. In the case of powdercoating, it's not good (relatively speaking), because the thickness of the powdercoat allows for the lower prepped area to invite corrosion and eventual poor conductivity.

It's not that easy to wire each individual light bulb circuit ground contact all the way back to a common ground (think speedo & tach lighting); some of these rely on the meter casing passing to the meter mount, passing through the yoke, then the bearings, to the frame, and eventually to the ground connection at the battery.

I don't have the Haynes book, but my Clymer book shows 2 wires going to the hole in the rear of the L bracket LAB mentions, but the pic is b&W so I can't tell but on my harness that is all it could be, but I have 2 double red wires. On the same page it shows a double pair going to the lower rear bolt of the triangular head steady plate and someone has marked it with a ground symbol, but the holes in my 2 double pair of red wires measure 0.195 and that is too small to go under those bolts. Then again, I found my notes on the harness, and it says "RED (2) go under capacitor mount bolt" so that gives credence to Tom's assumption that they go under the small capacitor mounting holes.

My notes also mention that the longer wires for the coil connections go to the left side which makes some sense because as I remember the harness traveled along the right side of the smaller tube under the tank.

I agree with GP that if you have powder coated, you must be careful how you ground things, a lot of the frame grounding on the original bike depended on internal or external tooth lockwashers to break through the paint to hit the bare metal, and P/C will preclude that.

Dave
69S

According to the Haynes manual, it seems the early Commandos had a short ground wire connection running from the left hand end of the lower rear engine mounting bolt to a bolt on the frame side stand bracket, of which it says: "...THIS MUST NOT BE OVERLOOKED...".

I have the same haynes manual as you do L.A.B. Unfortunately it is in B&W and although it shows one set of double wires bolted to said hole in the coil bracket, the other pair isn't clear. The picture also doesn't show the condensers mounted outboard as Daves shows(like mine) Does anyone have an original pre '71 to use as a reference? Another question would be 'why 2 sets of ground wires?" Overkill Must be some reasoning

Tom

TJKII said:

The picture also doesn't show the condensers mounted outboard as Daves shows(like mine)

Click to expand...

Neither photo 6.7 (p15) or photo 34.5 (p49) shows the condensors, but there is a reason, as both photos were taken from the right hand side, but look closely at photo 6.7a, (the one where the coils have been swung up and inverted on the frame tube) and that does show the two condensors in position on the coil brackets with the L/H one outboard of the coil bracket, however the R/H coil bracket appears to have been fitted the reverse way around, so the R/H condensor is on the inside of the coil, which is why it it's not there in the other two photos.

L.A.B. said:

According to the Haynes manual, it seems the early Commandos had a short ground wire connection running from the left hand end of the lower rear engine mounting bolt to a bolt on the frame side stand bracket, of which it says: "...THIS MUST NOT BE OVERLOOKED...".

Click to expand...

Yes, I remember that wire. I think it went from one of the kickstand mounting bolts to the bottom motor stud.

The reason I am unsure that the 2 double red wires mount under the condensers is why would I have taken them off if I didn't need to at that point in dis-assembly, but I am not sure. I know a couple of guys that have 69's and I'll see if they know.

Dave
69S

L.A.B. is correct about the frame to engine ground connection. Said cable was still attached to the kickstand bolt by whomever disassembled my bike.

Tom

I just checked my pictures from my '69S rebuild last year and there is a double red wire connected to a ring at each condenser and another ring connector at the right side head steady plate. My replacement loom from Norvil had a ring connector for the head steady that was too small. I was able to file it out so that I could attach it to the head steady plate where the old one was attached.

If your wiring harness is original, or even a fresh aftermarket you can't have too many grounds.

I suggest that you overlay a master ground loop, here is what I did when I built my own harness when it comes to the ground loop:

I carried a ground to the tail light for the 3 bulbs. I anchored it back to an eye roughy where your rectifier is.

I carried a ground to the headlight shell and shared it with any circuits that were drawing power. I anchored this pathway to the same point as above.

I carried a ground to the head, using one of the three headsteady mounting points, I anchored that to the same as the above.

In your case I would carry a separate ground to the coils and anchor it on the headsteady.

If you are still using the zenner diod as a regulator I would carry a ground from it to the master point behind the rectifier.

As GrandPaul mentiones be sure that your connections made bare metal to bare metal.

The bigf news is that every component that generates or uses electricity must have a very clear ground path back to every other component that functions likewise. You tie your master gounding point with a single 12 gauge (non-electric start models) connection to the battery. Do not trust the frame to be your big conductor, it is made out of an alloy metal that acts like a resistor, trust me on this, I tried it once and got a shock everytime I touched the handle bars (they were at a different electrical potential--and yes 12 volts can smart).

For ayone using an original OE harness your connections are probably corroded enough to be generating high resistance. A good maintenance routine would be to break and re-make all your connections adding a bit of new stress to the connectors. Nortons came with some pretty good ground loops, by maintaining the one you have, you can extend the life of your electrical system, but not forever...

RS, former Air Force Radar Tech

Nelson, am I understanding that you have 3 sets of red wires exiting the harness ?
My harness came from British wiring in Bally, PA. The only way mine differs from the wiring diragram in the Haynes manual is I only have one red wire going to the ZD.(doesn't loop)
Tom

My original harness has 2 double red leads coming out of it for the screws under the condensers, like I suspected from my notes. I think I remember a lead going to one of the allen bolts on the head, but there is nothing in my harness for that. Was that a separate lead, if so, where does it go? I'm thinking when I put it back together, I may add some ground wires to various points.

Dave
69S

I seem to remember the grounding wires on my '73 850 go on the Allen bolts that hold the head steady to the head, might be different on a '69 of course,
Dave.

So DogT did you buy Nelson's bike, or vice-versa. :mrgreen:

Your avatars appear to show the same bike.

Huffer,

No, Nelson has one just like mine and has been quite helpful. He got his finished last year I think, my frame is at the powdercoaters right now, so I have a way to go. Sidriley in Madison VA also has a 69, but he is doing his in a different colour and as a roadster. So there are 3 '69's between Charlotte and Hume, maybe even more.

Dave
69S