Is a power master switch a bandaid?

29tudorsedan

29tudorsedan

Member
This is just something I've had on my mind, unless you don't lock your doors when you're out in your A, is there really a need for a master switch for the whole car? Don't get me wrong, there's one on my car, but it came that way to me from the last owner, if there's nothing drawing on the system because everything is in good shape, does a master switch have another purpose?

The one thing I think is easier in my experience is when I was getting all the bugs out of the electrical system (maybe the reason a master switch was on the car in the first place) it was handy to just flip the switch, but popping the cover off the floorboard isn't too difficult either!

I guess if someone was very Model-A savvy and knew the car was in gear they could hop it forward by hitting the starter switch from the engine compartment.

Thoughts?

Happy new year as well!
 
I suspect that "theft deterrent" is pretty low on the list of reasons why people put a Master Switch on their A. The average person today does not know how to start an A, whether the battery is connected or not. My Dad leaves the key in his A all the time when parked. I only take my key with me when parked so that some joker doesn't walk off with it.

Most people use a Master Switch to prevent battery drain while the car is sitting between uses. On cars that have electrical issues, yes, this is a band-aid.

I have worked quite hard to ensure my electrical system is clean and tight and reliable. Still, my master switch has saved my bacon several times due to my error (left parking lights on, left dome light on, left ignition switch on after running carb dry). Even a perfectly restored car is subject to human error. :D

Yes, you can pull the ground cable off of the battery each time and get the same effect. I did that for over 10 years and got tired of doing it.

Happy New Year!

:cool:
 
Mine RHD so the starter rod is where passengers put their feet so I have 2
1 for the whole system and 2nd just for the starter this was add after a passenger (wife) step on the starter rod while we were driving killing the starter and ring gear
 
No not a bandaid , SAFETY. No custmers vehicle allowed in my garage with out one or battery disconnected, Why ask a certain gentelman in Newhall CA . 12 months of stress, two Model A,s destroyed , thousands of $$$$,s damage. Sure they never had when new BUT why take the risk for just a few $$$$,s I have them in all my toys. Wet new year in NZ
 
I also have a switch on each of my cars. It is mounted under the starter, I am in the habit of shutting off the battery after each use, and leaving the hood propped open on that side. That way at a glance I can tell they are all off. When I go to use the car, I remember to check the oil when I turn on the switch. It is also nice to turn off the switch at shows so people don't reach in and blow the horn or turn on the lights.
 
I had the alternator short out on one of my cars while it was sitting one day.
I happened to be working close, and got the wires off before the car burnt up.
It did let the smoke out of the alternator and some wires. That is when my cars got a cutoff switch. I always use them when in my garage. There are 6 cars and all my equipment in the garage. Would not want to loose everything.

In my case it has nothing to do with some one taking my car.
 
I have always installed them in my toys. When parked in the Garage or Barn, they are a part of my "process". I shut off the fuel, let it run out of gas, shut off the ignition, shut off the battery, put it in gear, and say goodnight. I was a mechanic in the service, all of our vehicles had one, our M816 recovery wreckers had a switch that disconnected the battery and tied in a trickle charger. For whatever reason one might use them, they are inexpensive, easy to install, and cheap insurance for a variety of issues that would probably never happen. But that is what insurance is for, protection against things that are likely not to happen.
 
I put one in just on the off chance that the starter might stick sometime, but it never has.
 
Is a power master switch a band aid?

Maybe but I would call it a insurance policy.
What happens when the battery cable rubs on the brake pedal until it rubs through. Seen this happen more than once.
What happens when the repo amp meter shorts on the gas tank.
What happens if the coil shorts out it is hot all the time.
What happens if one of the wires from the starter that goes to the dash rubs and shorts out.
What happens if the cut out on the generator sticks closed.
What happens when the light switch and wires short out.
What happens when the brake switch or wire shorts out.

Maybe your insurance will pay for every thing. Do you want to find out, I don't.
 
"if there's nothing drawing on the system because everything is in good shape, does a master switch have another purpose?"

Ah - but that pre-supposes that everything IS in good shape, and always will be (i.e. you'll never, ever get a short somewhere).

I haven't been around Model As all that long, but one thing I have learned in life is to hope for the best, but prepare for the worse. As others have stated - it's cheap, easy insurance.
 
Ok, I will be the other side of the question. If you have a fuse located at the starter switch, all the wiring to lights, gen., ign etc is protected by the fuse. Then the only thing left unprotected is the short main cable from the battery to the starter switch. Nearly ever car running down the road is the same. The cut out switch is another "modern improvement" that is really another gadget subject to failure. I never understood why it is any easier to remember to disconnect the main switch than to turn of the key and lights. A quick glance and walk around the car to make sure gas and switches are all off is a better answer.
 
Seems like I remember someone here on FB that had built an alarm (like a modern car) that would sound if you left your lights on and the switch off. That I could go for!
 
Phil is not the fuse located on the starter a modern gadget ??? that gives far more problems than a cut out switch ?? So You better jump back over the fence ?? One MAY trust your own vehicle wiring BUT what about a custmers vehicle. ?? Thats what started the big fire in Newhall last year, I know as been there & saw the damage & the 12 months of stress not to mention the loss. A cheep safty item that is the 1st thing i fit on any new A , & recommend to other owners , I do not run a modern fuse set up , seen too many failures with them ,
 
I have always installed cut off switches on my cars. I have also added one to my wifes car. I just have to add one to her other car, a 1930 Chrysler. Just looking for the best spot to install it.:) after seeing what happened to Rons garage/workshop because of a wire short in a car I am glad I have them and use them. Like Quickchange stated it was big loss. And has been a long process for him and his wife to be made whole again by the insurance company.
 
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I just looked and I have a glass fuse on the top of my starter. Does this protect me against a short & fire or is it just to protect the starter? Do I still need to install a switch like you all have been discussing?

Thanks,

Randy
 
The fuse hold on the starter is not all good. For one thing you do not want a fuse on the ignition. Modern cars that I have worked on do not . They may have fuse link wire. But you would not find one fuse for every thing.
If the fuse blows in heavy traffic your engine is going to quit. If you are going to use a fuse, use one for each circuit with the proper amp fuse.
 
George Miller said:
The fuse hold on the starter is not all good. For one thing you do not want a fuse on the ignition. Modern cars that I have worked on do not . They may have fuse link wire. But you would not find one fuse for every thing.
If the fuse blows in heavy traffic your engine is going to quit. If you are going to use a fuse, use one for each circuit with the proper amp fuse.
Click to expand...

most modern cars do have one main fuse in the engine area junction box to protect all the other fuses. they also have individual fuses for all the circuits ign,comp,fuel etc. if one was to jump start a car backwards per say pos to neg by accident it would blow the main fuse usually 100 amp protecting all the rest. a short in the ignition system on a modern car can blow a fuse and cause the car to die.
i like having the fuse on my A starter and a main shutoff under the seat incase the starter switch sticks
 
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We have a disconnect on our fire truck AA. We came back from a parade with our model aa in a 40' enclosed trailer. A neighbor to our fire station called me 3:00 am and said our trailer was making a noise. I went down and opened up the trailer and found the horn had started blowing on its own and was stuck on . The driver forgot to turn off the master switch and it had rained the whole parade and shorted out the horn somehow, Thankfully it didn't catch on fire.
 
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