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#659233 - 07/03/16 11:50 pm 1969 triumph bonneville T120R wiring harness  
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jchildr Offline
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Nashville TN
Is the red ground wire in the wiring harness on my 1969 triumph bonneville actually one long single continuous wire mounted at different points along the frame all the way to the positive battery terminal? For example, my wiring harness has six grounding points. These mounting points have two wires on a single connector, except at the positive battery post. The first mounting point is inside the headlight shell on one of the bolts that mounts the headlight shell to the mounting ear. Then at the base of the zener diode. Then at the horn relay mounting bolt. Then at the base of the rectifier. Then at the oil tank mounting bolt. Then finally at the positive post of the battery. Just curious. Thanks.

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#659247 - 07/04/16 5:12 am Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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bleep it through?

#659249 - 07/04/16 5:47 am Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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Hi,

Originally Posted By jchildr
Is the red ground wire in the wiring harness on my 1969 triumph bonneville actually one long single continuous wire mounted at different points along the frame all the way to the positive battery terminal

Yes and no.

Physically, there are numerous individual Red wires, that's why "These mounting points have two wires on a single connector, except at the positive battery post"; if you dismantled the harness, you'd find that each of the "two wires" at any "single connector" links to another connector. Electrically, they're all connected together.

Personally, I don't like the Lucas "ground wire" implementation, copied by most pattern harness makers; frown it's a big loop connecting (nearly) all electrical components together with the ends of the loop at or near battery positive; as the harness ages, if any wire breaks, the components are still connected to battery positive by the other side of the loop; however, once there's a second wire break, the components in between the breaks aren't connected to battery positive any longer. facepalm When I build a harness, the "ground" wires mimic the supply wires - one of each between each component and a junction ("ground wire" junctions in the headlamp shell and under the seat), junctions joined to battery positive or negative as appropriate; if anything fails, the failure is easy to diagnose.

Originally Posted By jchildr
The first mounting point is inside the headlight shell on one of the bolts that mounts the headlight shell to the mounting ear. Then at the base of the zener diode. Then at the horn relay mounting bolt. Then at the base of the rectifier. Then at the oil tank mounting bolt.

Uh-uh, 'fraid you and/or the harness builder made several mistakes. smile

The connections you've listed are so specific components that "ground" through their mounting have a wire (not cycle-parts) electrical return path to battery positive:-

. "inside the headlight shell" - Original headlamp shells had a loop rivetted in the bottom of the shell, that took a bullet terminal on the end of a single Red "ground" wire; afaict, this was just for the single-wire pilot bulb holder that "ground[ed]" through its mounting in the headlamp reflector, later superseded by a two-wire holder, one wire then being the "ground";

.. if your harness really has a ring terminal here, that's a pattern modification, possibly because either the original rivetted loop becomes useless due to corrosion that cannot be removed between it and the headlamp shell or many pattern headlamp shells do not have the rivetted loop;

.. the original BPF headlamp bulb 'cap' should have another rivetted loop to take another single Red "ground" wire bullet terminal; if you've replaced the headlamp with one that uses an H4 plug, one of the spade terminals is the bulb "ground" and should be connected to the Red wires;

.. the two idiot lamp holders should have two wires each, one each is the "ground" wire;

.. if the speedo. 'n' tacho. bulb holders have only a single (supply) wire each, the mounting plate will need a "ground" wire connection, as it's electrically-insulated from the rest of the cycle parts by the Metalastik anti-vibe mounting bushes.

. "at the base of the zener diode" - The Zener itself "grounds" through its mounting stud, the nearest practical electrical "ground" is the heatsink mounting bolt to the lower yoke.

. "at the horn relay mounting bolt" - Nope; a relay is a switch; by definition, it cannot "ground" through its mounting. The correct 33188 6RA relay has only three separate terminals - supply (Brown/Blue wire to "C2" terminal), 'low power output' (Brown/Black wire from "W1" terminal to horn button), 'high power output' (usually black wires from "C1" terminal to the horns); the "ground" shown in some wiring diagrams is a Meriden Misprint; facepalm

.. however, neither the original '69 twin Clearhooters, the later twin Clearhooters (listed in '70 parts books) nor the eventual HF80's "ground" through their mountings, so a Red "ground wire" in this region is likely for connection to the horns "ground" wires or terminals.

. "at the base of the rectifier" - Like the Zener, the rectifier "grounds" through its central mounting stud.

. "at the oil tank mounting bolt" - Mmmm ... the oil tank is a well-known electrical component ...

One thing you have missed is the Red "ground" wire connection to the engine, usually on one of the cylinder-head/rocker-box/head-steady studs; standard points and spark-plugs "ground" through their mountings so need a Red wire connection to battery positive.

One standard '69 electrical component that doesn't have a "ground" wire connection that should have is the rear lamp. If you have the patience, copy what Lucas did as standard mid-'71-on - a Red wire parallel to the Brown and Brown/Green wires all the way to a bullet terminal into a loop soldered to the bulb holder. In any event, the Red wire needs connecting at least to the internal 'frame' that mounts the bulb holder and the lens.

Finally here, if the harness has only one "ground wire" on battery positive, consider fitting a fuse holder and 15A fuse here. Reason I suggest this is, because this wire connects the cycle parts to battery positive ("positive ground"), if something metallic (e.g. broken seat pan, loose tool or part, etc.) touches the battery negative terminal, it makes a short-circuit that won't blow the standard fuse in the Brown/Blue wire, because the short isn't through that fuse. eek However, a fuse in the wire to battery positive would blow, protecting the battery. bigt

Hth.

Regards,

#659267 - 07/04/16 8:52 am Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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jchildr Offline
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Thanks Stuart. I understand.

#659271 - 07/04/16 9:39 am Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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There is also a separate RED "return" wire at the rectifier, about 7 inches long. Being separate from the harness it is often discarded during restoration, or worse yet, not supplied with the new harness at all. However, it is of the utmost importance.

This short wire connects the rubber mounted rectifier base (the positive connection of the rectifier's 4 connections) to one of the top oil tank mounting bolts. Without this wire, the charging system won't work (no return path for the rectifier output), AND the spark plugs may not fire (no return path for the ignition spark back to the battery).

A much better plan is to replace this 7 inch wire with one from the rectifier base all the way to the rocker box. For one, the rocker box is a direct connection to the engine cases. Secondly, the frame is a poor place to try and connect to the engine, and the top oil tank mounting bolt is the poorest of all frame connections. This connection was finally done this way in 1971 when they converted over to the OIF.

Hope this helps. bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
#659280 - 07/04/16 10:22 am Re: 1969 triumph bonneville T120R wiring harness [Re: RF Whatley]  
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Hi Richard,

Errrm ...

Originally Posted By RF Whatley
This short wire connects the rubber mounted rectifier base
to one of the top oil tank mounting bolts. Without this wire, the charging system won't work (no return path for the rectifier output),

When I wrote in my previous post, "the oil tank is a well-known electrical component ...", that was irony ...

. Neither the original Lucas 'Ritz cracker' circular-plate rectifier nor the after-market square potted rectifiers are "rubber mounted"; you're thinking of something else ...

. The battery and rectifier are connected in parallel. With a Brown/Blue wire between battery -ve and the centre plate terminal of an original rectifier (or the "-" terminal of an aftermarket one) and a Red wire between battery +ve and the centre stud of an original rectifier (or the "+" terminal of an aftermarket one), what is a wire from the rectifier "to one of the top oil tank mounting bolts" going to do? confused

Originally Posted By RF Whatley
AND the spark plugs may not fire (no return path for the ignition spark back to the battery).

The spark plugs are screwed into the cylinder head. If there is a Red wire between one of the cylinder-head/rocker-box/head-steady studs and battery +ve, why would the spark plugs not fire? confused

Originally Posted By RF Whatley
A much better plan is to replace this 7 inch wire with one from the rectifier base all the way to the rocker box.

In the o.p.'s first post, "my wiring harness has six grounding points ... at the base of the rectifier." In my previous post, I mentioned that he should find a Red wires terminal that fits "on one of the cylinder-head/rocker-box/head-steady studs"; what would another "one from the rectifier base all the way to the rocker box" do? confused

Fwiw, I've now owned my '69 T100 for about thirty years; a '69 T100 is electrically-identical to a '69 T120.

Regards,

#659299 - 07/04/16 2:23 pm Re: 1969 triumph bonneville T120R wiring harness [Re: Stuart]  
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Well. I don't have a ground wire connected to one of the cylinder-head/rocker-box/head-steady studs. So I guess the engine is grounded just by being mounted to the frame. I also don't have a rubber mounted rectifier base. The bolt that mounts the horn relay also mounts the condenser pack. So I guess the ground wire mounted there is grounding the condenser pack. Thanks for all info.

#659305 - 07/04/16 2:47 pm Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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Hi,

Originally Posted By jchildr
I don't have a ground wire connected to one of the cylinder-head/rocker-box/head-steady studs. So I guess the engine is grounded just by being mounted to the frame.

It's unwise to expect this, particularly with careful painting/powder-coating and assembly. Lucas supplied Red wires between electrical components and battery +ve because it was far more long-term reliable than random cycle parts rubbing up against one another, that were/are either well-coated with non-conducting material or corroded, which is also non-conducting ... At least one Red wire ran from the headlamp area to battery +ve, over the top of the engine; for the sake of one washer and a bit of soldering, why would they not connect it/them to the engine so the engine's electrical components were also reliable for owners? confused Long-term reliability is the same reason Lucas eventually fitted a Red return wire to the rear lamp too.

If you're sure the harness doesn't have (a) Red wire(s) with a ring terminal that should be attached to an engine bolt, ime it's definitely worth adding one, a cylinder-head/rocker-box/head-steady stud is convenient, from one into a convenient existing Red wires' connection in the harness.

Originally Posted By jchildr
The bolt that mounts the horn relay also mounts the condenser pack. So I guess the ground wire mounted there is grounding the condenser pack.

Good spot. bigt All my Triumphs and most of my other bikes have electronic ignition so it's a long time since I dealt with the other gubbins that points need ...

Hth.

Regards,

#659308 - 07/04/16 3:09 pm Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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jchildr Offline
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Thanks. I will add the proper ground wiring. Actually, my bike is at the shop being partially re-restored. Obviously the previous restorer did a poor job. I'M also getting electronic ignition. Thanks again for your help.

#659310 - 07/04/16 3:39 pm Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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What is this definition of "restoring," who did the first one, and who is doing THIS one?

I can't help it. I'm curious.
Some so-called "professionals" AREN'T.

#659553 - 07/06/16 9:05 am Re: 1969 triumph bonneville T120R wiring harness [Re: Stuart]  
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Originally Posted By Stuart
. Neither the original Lucas 'Ritz cracker' circular-plate rectifier nor the after-market square potted rectifiers are "rubber mounted"; you're thinking of something else ...


Hi Stuart -
Sorry, but the Lucas rectifier is sitting on a tab at the rear of the battery box. And the entire battery box on all Triumph twins is rubber mounted at all 4 corners as you can plainly see in this photo of a 1966 model Triumph twin...

[img]https://lh3.googleusercontent.com/yya5bp...4=w1143-h857-no[/img]

In fact, in that photo, the stock Lucas 7 inch wire is laid on the bike to show its position on the stock bike. I laid that wire there more than 7 years ago because I knew you would someday need to learn this. laughing

Originally Posted By Stuart
. The battery and rectifier are connected in parallel. With a Brown/Blue wire between battery -ve and the centre plate terminal of an original rectifier (or the "-" terminal of an aftermarket one) and a Red wire between battery +ve and the centre stud of an original rectifier (or the "+" terminal of an aftermarket one), what is a wire from the rectifier "to one of the top oil tank mounting bolts" going to do? confused



Since the battery box and aforementioned rectifier ARE rubber mounted, the 7 inch RED wire is going to connect the rectifier base to an actual part of the frame. The part of the frame it connects to is one of the 2 flat struts that support the top of the Triumph oil tank.


I'm not really sure why you feel so compelled to jump on every comment I make with both feet. You've done this without stopping for more than 10 years now. Sir, with all respect, you really need to get off the keyboard and get a life.

All the best! bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
#659555 - 07/06/16 9:15 am Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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Nashville TN
I do have a red wire in the harness connecting the base of the rectifier to the front oil tank mounting bolt. Then I have a red wire from the same oil tank mounting bolt to the positive post of the battery. This is suppose to ground the frame to the electrical system. Since I have no red wire connected to the rocker box (engine) nor to the taillight, the frame is grounding the engine. Since the taillight is mounted to the fender and the fender is mounted to the frame, then the frame is also grounding the taillight. This does work. I know from everyone's comments that this setup is not good and I will fix it. Thanks.

Last edited by jchildr; 07/06/16 7:12 pm.
#659563 - 07/06/16 9:34 am Re: 1969 triumph bonneville T120R wiring harness [Re: jchildr]  
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Originally Posted By jchildr
I do have a red wire in the harness connecting the base of the rectifier to the front oil tank mounting bolt. This is suppose to ground the frame to the electrical system.



Exactly! And that's as it came off the production line. And it's there ONLY because the battery box is rubber mounted, and therefore electrically insulated from the frame.

If you have added a return wire to the rocker box and tail lamp, then the aforementioned wire is really doing nothing, except to keep the wiring stock looking. This because the there is nothing in the "frame" that needs an electrical return path. The items needing a return path to the electrical system were: the points, spark plugs and tail lamp. And none of those 3 items actually touch the frame. So by adding the rocker box and tail lamp RED return wire, you've reduced the number of bolt connections to complete the same electrical path. And those more direct electrical connections added reliability.


All the best. bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
#659565 - 07/06/16 10:39 am Re: 1969 triumph bonneville T120R wiring harness [Re: RF Whatley]  
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Stuart Online content
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Hi Richard,

Originally Posted By RF Whatley
the Lucas rectifier is sitting on a tab at the rear of the battery box. And the entire battery box on all Triumph twins is rubber mounted

Yes, but, as I quoted in my previous post, from the o.p.'s original post:-

Originally Posted By jchildr
red ground wire in the wiring harness on my 1969 triumph bonneville
my wiring harness has six grounding points
inside the headlight shell
base of the zener diode
horn relay mounting bolt
base of the rectifier
oil tank mounting bolt
positive post of the battery.

(my underlines). As you have quoted from my post:-

Originally Posted By Stuart
. The battery and rectifier are connected in parallel. With a Brown/Blue wire between battery -ve and the centre plate terminal of an original rectifier (or the "-" terminal of an aftermarket one) and a Red wire between battery +ve and the centre stud of an original rectifier (or the "+" terminal of an aftermarket one), what is a wire from the rectifier "to one of the top oil tank mounting bolts" going to do? confused

To be clear: because the rectifier is "grounded" by the Red wires between its base and battery positive - that the o.p. detailed in his very first post - a wire to the oil tank serves no useful purpose whatsoever. "connect[ing] the rectifier base to an actual part of the frame" doesn't do anything, the frame is an inanimate collection of painted bits of steel.

Originally Posted By RF Whatley
I'm not really sure why you feel so compelled to jump on every comment I make with both feet.

Have you considered asking yourself the same question? Fourth post into this thread:-

Originally Posted By jchildr
I understand.

... then you start posting about rubber-mounted rectifiers, 7-inch wires to the oil tank, etc. confused The thread is now nearly four times as long; does it contain even twice as much useful information, never mind four times as much?

Originally Posted By RF Whatley
Sir, with all respect, you really need to get off the keyboard and get a life.

Again, have you considered taking your own advice?

bigt

Regards,


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