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MG MGB Technical - Anti theft idea

I had what I think is a good idea for an anti-theft device in my car.

My car, heavily but tastefully (I hope!) modified, has a push start button. I still have the in dash key switch though. I have one I pulled out of an old Morris Minor at the junk yard. It only had three positions, off, run and start.

My thinking was I wouldn't use the start position. But then I thought what I can do is still have the start position run the starter but also have it switch a relay that grounds out the coil like a normal physical kill switch.

If anyone attempts to starts the car that way it will turn over but never fire. Ripping the wires out from the dash won't help as the relay will be hidden somewhere. It shouldn't be immediately obvious why it isn't starting.

Of course the actual start button is there in plain sight but with this system I have no hidden switches to remember to turn on.

What do you chaps think?

Simon Jansen

I take the rotor with me.
Rick Ingram

Well, I am going to have one of those little leather straps on the bonnet so opening it every time I go somewhere might be annoying! I also have the big battery cut off switch mounted down on the heel board so I can take the key from that with me too.

My original (extremely short lived) idea involved the brake light warning switch on the handbrake cutting out the ignition. You had to take the brake off to disable the ignition kill switch. Of course this might cause issues on hill starts :)
Simon Jansen

Simon. The first question with any form of defense is, "What is the threat?". From that, we decide what defensive measures need to be taken. The majority of the threat in my area falls into two categories:

First, vehicles ten years old, or less, that are stolen to part out at a "chop shop". Such parts are sold off to body shops and auto salvage yards.

Second, some of the higher value vehicles, mainly SUVs, ticked out pick up trucs, and luxury cars, which are stolen by Mexicans to be taken down into Mexico and sold.

The average automobile that is over 10 years old has a very low threat of being stolen unless it is some form of exotic automobile. In my area, the MGB is not considered an exotic automobile, would be difficult to move within the local area (i.e. because most of us know each other's cars), and would not bring a sufficient return on the investment to make it worth while to steal and transport outside of the area. Especially if the car had been heavily customized and could be easily recognized if it were spotted on E-bay or some other mass marketing system.

My experience is that, in most cases, the MGB is not worth stealing. Thus, any defenses need to be directed against the casual thief (joy-riding) rather than the professional thief. Your incorporation of the push button starting system would be sufficient to stop any younger person I know from being able to start the car. They have never seen a vehicle that had a separate switch to activate the starter. Thus, the use of a separate switch to control the starter will be sufficient in most cases for the level of threat that most of us would face.

Les Bengtson

Les, you're right. It's mainly joy riders that would be the problem. Anyone really intent on stealing it would winch it onto a truck. No need to start it at all!

Cars being stolen by Mexicans isn't really much of an issue here us being way, way south of the border perhaps :)

When I had my GT someone tried to steal it once but they obviously didn't know about the choke and couldn't get it started!

Push button starters are making a comeback though on high end sports cars if episodes of Top Gear are anything to go by.
Simon Jansen

I am still of the view that the most effective deterrent is a switch on the fuel pump.

It allows the car to start and run but the engine will stop and not restart after a few minutes, leaving the thief probably in a position that will attract attention if he tries to fix the "broken" car - more likely than not he (or she) will just curse about crap old cars and go nick something else.

Most modern cars can't be hot wired etc - most have their keys stolen from an unlocked house at night!
Chris at Octarine Services

Fuel pump switch is what I had in my old GT and I also wired it into the fuel gauge so when the pump spluttered the gauge was readying empty.
Simon Jansen


If your engine starts easily, I think that when the would-be thief lets the key off of the crank position, the momentum of the engine will let it start because the ground out of the coil will no longer be in play.

C R Huff

Charley, yes that occurred to me too. I think I will just rely on the big red battery cut off key and the alarm and the push instead of key start. I am not likely to be leaving the car anywhere dodgy and all these things are just extra complexity.
Simon Jansen

Simon - wasn't it you who send me the pictures of the special pawl for a fly off hand brake? That is probably the single most effective anti theft device that there is. The T series cars and the MGA's had that type of hand brake and I remember when I was in high school and my folks gave me an old TD, of course with the admonition that I was not to let any of my buddies drive it. So how does a high school kid deny his buddies a quick drive around the block? I just told them that if they could release the hand brake they could drive the car - none ever drove it. I have since had a number of the pawls made and can provide you one to add to your repertoire of anti theft devices. Cheers - Dave
David DuBois

I made a special car cover, when I out it over my MGB, it looks like this (image). NO ONE will steal that.

David Steverson

Ah, the Liverpool anti-theft device, available in several designs -
Paul Hunt

I happen to like this anti-theft device:
Steve Rechter

Then, there's always the modern car thief who can't use a manual gearbox.

My MGA and BGT both have fuel pump switches. I get about two blocks when I've forgotten to switch them back on. I think Chris (Octarine) is spot-on.

I like the idea of Simon Jansen's to also connect the fuel gauge to the fuel pump switch.
Fraser Cooper

This thread was discussed between 17/09/2009 and 07/10/2009

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