On all my prior builds I’ve always installed a hidden switch in the electrical harness as an anti theft deterrent.
In the past, I generally install it between the coil and its 12vdc source so everything works in the car or boat but when the switch is open no voltage will go to the coil.
Simple!
I’m thinking on this build about installing the switch pictured below between the battery ground lug and the chassis ground point.
This will disable every component so the starter won’t even crank and the switch has a removable key.
I believe that disrupting the ground is better than installing the switch on the positive cable between the battery and the starter.
I know this will stop the clock as well, but I don’t mind resetting the clock or I can run the clock on a complete separate isolated circuit so it continues to run.
Since I’ve never owned a C3 I really know nothing about their wiring circuits.
What do you wiring pro’s think?
Should I install the switch on the ground or positive cable?
I am running MSD ignition with a 6AL box, a Vintage Air system, and I’ve upgraded to electric headlight actuators and dual Spal electric fans.

 

Another idea, install a remote switch on the starter solenoid or coil wire inside or outside of the cabin...
Key on everything would work but until you click the remote to ON no power to solenoid or coil...
Something like this 12vdc 40amp unit...

 

You would wire your +source & -chassis ground in, just your +source out...no second negative on the out side...

 

Those are great ideas!
I’ll look into those as options.
Thanks!

 

Old-line brand Cole Hersee
offers several Heavy Duty USA options
https://info.littelfuse.com/cole-hersee

 

...or just install one of those simple blade type battery cutoff switches (**** type are a tight fit in C3s).

 

I believe the switch I have was manufactured by Cole Hersey and sold through All Star Performance.

I like the switch I have because it is heavy duty and a mechanical disconnect where nothing can fail.
My 73 had one of those blade type disconnects at the battery when I bought it and it was really junk.
This one I can mount where it is accessible from the drivers seat and any time I want to completely disconnect the electrical, I can then take the key with me.

My question was more about whether to install it on the positive or the ground and if either would negatively affect the electrical in the car.

 

Perhaps the C-H site's specs/ per P/N also addresses whether a device P/N is compatible in Pos or Neg application.
In addition to those like that one from allstar, C-H offers several other 'Removable Key' disconnects.
I saw that Pos-Neg somewhere; perhaps on C-H site. DC versus AC. Good that you question compatibility

 

Hey Greg-

I'd use it on the ground side- heavy equipment/truck use the ground as it is safer. And you always disconnect the battery's ground first before replacing.

However the NHRA/NASCAR & SCCA requires positive side...
but it's used to turn the switch off when running- as a fire/accident -theoretically the alternator can still be supplying +12v

 

^^^THIS^^^
so very true that alternator may continue to power ignition if disconnect is on ground side. (reason why some race sanctioning bodies prefer it on + side).
Disconnect on Either side will likely prevent a hot theft; but nuttin' stops a rollback or ******.

 

Yes agree with Rebel Yell...other than axle/wheel clamp locks or chains to a tree or explosives ...a real professional team with a wrecker will tow it and load in a truck if they really want it...alarms only stop the common thief...

 

Thanks Richard,
My thought has been the ground side as well.
As I said, it’s basically a theft deterrent and I have no plans to race the car.

 

I personally prefer the hidden switch to the distributor or coil.
The complete disconnect will stop the clock and perhaps kill the radio memory.
I like having a working clock.

 

Radio's since the 90's have used car radios have used non-volatile memory (NVM)- like a flash or EEPROM
to store essential settings (stations, audio levels, Bluetooth pairings).
The car's clock? Just make sure you hit the switch at the same time- and it'll be correct!!!

 

You don't need to disconnect the whole 12V system. It's overkill. You just want to prevent the engine from starting. A well hidden switch to interrupt the power to the coil is all you need.

 

My car has the radio delete and I won’t ever add a radio, so nothing to worry about and I can just wire the clock with its own circuit so it stays on continuously.
Don’t forget guys that all the wiring is currently removed from my car and I’m replacing all the harnesses with new, so any wiring changes is simple at this point in time.
Just adding the switch to interrupt the 12vdc to the coil is one of the options I’ve done in the past.
It works great, and I could still use the disconnect switch I have.

 

I think I have seen people here put a toggle switch on the neutral safety switch wiring under the console where the automatic cars have it. I believe the wiring harness has a plug both on the pedal for the 4 speeds, and under the console for the auto's.

 

You are correct and I just ordered the neutral safety switch for the clutch pedal assembly as part of the auto to manual transmission conversion.

 

For the street just put it on the ground side. When installing a battery the ground is the last connection that should be made so it just makes sense to put a cutoff switch on ground unless you race and your sanctioning body requires it on positive.

 

You probably have made your mind up on this subject but I happened to have found this switch installed on a 68 I was looking at on BAT