Starter switch/box grounding strap location and type?

[Lahti35]

I've read some discussion here about the grounding of the starter switch/box and have seen several electrical diagrams that show the box being grounded. My 1920 is currently grounded to the horn mount via a wire running from the starter switch/box terminal labeled ground. 

 

Myers offers these ground straps based on the year in their catalog (with picture):

 

I'm thinking my horn mount ground is incorrect and an old work around... Does anyone know where these ground to? Transmission/bellhousing bolt maybe?

 

[cutdown]

That strap ground the starter switch to the steering column, to steering box,  to chassis and then to engine. If you  have a good ground wire to the engine that should be sufficient. As the horn is bolted to the engine, that is supposed to work, but best to have a decent ground wire frame all electrical bits, back to the battery and engine. 

 

Grounding through multiple connections and especially through paint should be avoided.

 

An example of what not to do was demonstrated years ago by someone who had fully rested an old Indian. He could not get the lights to work properly because all parts were thoroughly painted. He then proceeded to remove that paint from all mounting surfaces when he could have run an earth wire back to the battery parallel to the feed wire on all electrical devices [ including the engine ].

[Lahti35]

Anyone have a picture showing the location, I haven't been able to find one yet.

 

The ground wire on mine looks to be a much later addition and I'd like to deep six it with the correct unit.

 

Thanks for the info Cutdown, very helpful!

[cutdown]

I just took photos of mine before I realised my car is rh drive '23. Might help though but not easy to see where it is. Lh pic shows where it is bolted under the floor board by the steering column. The rh pic gives a wee idea of its shape near the steering box. It could be the same as the one in the middle of photo above.

Edited June 12 by cutdown (see edit history)

[Lahti35]

Thanks Cutdown, makes sense now! 

[Mark Gregush]

Thanks for posting the photos of one installed. While I haven't had any running/charging issues so far, I will take a look at mine and see if I have a strap installed. 

Edited June 14 by Mark Gregush (see edit history)

[Jack Bennett]

On 6/9/2024 at 7:39 PM, Lahti35 said:

I've read some discussion here about the grounding of the starter switch/box and have seen several electrical diagrams that show the box being grounded. My 1920 is currently grounded to the horn mount via a wire running from the starter switch/box terminal labeled ground. 

 

Myers offers these ground straps based on the year in their catalog (with picture):

 

I'm thinking my horn mount ground is incorrect and an old work around... Does anyone know where these ground to? Transmission/bellhousing bolt maybe?

 

It would be criminal to under emphasize the importance of providing a good ground for the starter/generator switch/cutout relay box. 
The two relays are grounded to the case base, and, if activated singularly, the little ground wire which provides grounding necessary to connect the battery to the starter motor winding via the floor switch, and then the 2nd relay which directs the high starter amperage away from the generator, would be sufficient. 
The recurring problem which destroys the relays in this box is the absence of a good ground when the engine starts and the relays both activate, one to remove the high amperage current away from the generator, and the other to use its heavier gauge outer winding to redirect the charging current now being produced by the generator to the battery, and the hair fine inner windings of this coil to latch the relay circuit closed, and complete the generator/battery charging circuit until it is broken by turning off the clum type ignition switch.

If not sufficient to handle this amount of current, and instead of directing it away from the internal windings of the latching relay to ground, and instead allow is it to use the ground wires of the relays, the relays overheat, and can actually catch on fire.

This strap runs from a lug screwed into one corner of the starter switch/generator cut out relay box, marked “ground”, to the bolt which extends the steering column to the frame.

I deduced that the strap, if intended for use solely as a electrical ground, would be overkill unless it is considered it also provides some essential support to the switch box considering it is mounted on a wooden floor, and surely gets loose through time and use.

A tiny amount of wiggle in the mounting of this box, which cannot be ignored since it houses a stomp switch which must be depressed every time the engine is started, and is held in place by four 1/4” bolts, will allow a lesser stabilized means of grounding the box to loosen and eventually fail.

The reality that this same area of the floorboards must support the repeated use of the clutch and brake pedals and have the accelerator pedal bracket bolted directly to it cannot be ignored either.

Perhaps it was intended that the mass of this strap, since it is routed directly beneath this area of strain on the floor boards, is to provide some structural support to this potential failure site.

I don’t particularly like the idea of combining the starter and generator, and relying on a heavy chain to drive it. But, I have too accept the fact that it is a part of my antique Dodge, and it must be maintained exactly the same way I tend to all other potential, vexing and expensive problems which are a inherent part of owning these old time machines.

Jack

 

Edited September 17 by Jack Bennett (see edit history)