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MG MGB Technical - Ignition Kill Switch - As theft detterant

Hi all,

I am looking to install some sort of ignition kill switch on my 67B roadster.

My thoughts are that alarm systems don’t really do the trick. So many times, you hear alarms going and they are pretty much ignored. So I’m not going to go down the track of installing a loud horn which may be set off by accident and probably be ignored.

So... I'm thinking that I just want to immobilise the car instead. I am wanting something simple and easy to install. My main points/thoughts are:

1. I don’t want a fuel pump 'kill switch' as I don’t want the car driven (albeit a little way) to where it may be abandoned and left in a dangerous position.

2. Its location... Any tips on somewhere which is easy to get to, yet not obvious to any potential thieves as where a kill switch would be hidden.

3. I have heard of someone using a mono 3.5mm headphone jack as a circuit switch. This is not an obvious switch so may be missed by thieves. Anybody heard of this or any other creative methods with kill switches?

I know that if they really want the car, not much will stop them.... but if I can stop most potential theives in their tracks, that would be great.

Look forward to hearing from you all

Safety Fast!
Mark
Mark Duggan

Mark,

I would just mount a toggle switch under the dash that kills the power to the coil. Put it out of sight and in a convenient place to reach, and that should do the trick.

Then, for extra safety, put another toggle switch in a different location for the fuel pump. If they hotwire your car to defeat your coil switch, I think it is not likely that they would find the fuel pump switch in the heat of the moment.

Charley
C R Huff

Thanks Charley,

I guess the kill switch for the coil needs to be carefully selected... Keeping in mind that the load generated by the coil. A garden variety 'dash switch' wouldn't last long here?

Also... good idea bout using them both in conjuction with each other. It would be sensible to locate this in a different position from the coil kill switch.

Any other tips anyone?
All feedback gratefully received.

Thanks
Mark
Mark Duggan

I have a battery cutoff switch mounted on the wall behind the driver's seat.

Although I don't have occasion to use it, I also have a paging alarm.

Dan Robinson

Mark
Like Dan I have a battery isolator switch on the panel behind the driver's seat. The switch key can be removed when required. The additional benefit is that the battery is isolated whilst the vehicle is not being used ensuring no leakage and flat batteries. I also plug a battery conditioner in whilst the vehicle is garaged.
Peter M (member)
Peter M

Mark,

I am no electronics wizard, but I have driven from daylight to dark with a hot battery and a failed generator. So, I don't think the coil draws that much. My 63 BSA C15 indicates about 5 amps when I switch the key on. I would think most toggle switches should handle that.

Charley
C R Huff

Mark - Charley is correct, most any standard toggle switch will handle the current for the coil. The 67 MGB has power to the coil routed through the tachometer, all you would need to do is cut that wire and run it through a switch. A battery cutoff switch with a removable key is also a good anti-theft device. I have one of those that is mounted up near the firewall on the right foot well, where it is really hard to see. I also installed a Facet fuel pump as a permanently mounted backup pump and have the power for the primary and the back up pumps routed through a single pole, double throw, center off switch that can add to the confusion of any would be thief. None of these deterrents are nearly as effective as the 95 pound, black German Shepard that my wife used to leave in our TD when she had to go to night meetings in town :) Cheers - Dave
David DuBois

http://www.vehicle-wiring-products.eu/VWP-onlinestore/home/homepage.php

Mark, These people do a cut off switch kit that I fitted to my Roadster. I found the best place to fit it was on the floor just in front of the drivers seat. I can reach down with my left hand an turn it off with ease. My reason to fit this was (a) for security and more importantly for me was an anti fire risk. Much of the wiring on an MGB is nor fused and if a short occurs it can catch fire, in particular under the dash board, (as it did on mine) By fitting a cut off switch where it can be reached easily can be a life saver. On a right hand drive car the battery cables run on the right side of the transmission tunnel. If you position the switch there and run the negative cable through the switch. Make sure it does not foul the seat runners. Hope this helps. Trev
Trevor Harvey

I hope no burglars are reading this thread, gentleman!!

battery cutoff switches are nice and convenient, but also alert suspicion when there is no juice to the starter...that's why cutting off power to the coil is nice, as is removing the rotor (albeit that's less convenient for day to day trips!!).

Curtis Walker

I would not have a switch to cut the power to the coil. Thieves often start a car by clipping a lead to a live fuse, or other live item, and then to the coil. A coil switch would not then prevent starting. You need a lead from the side of the Distributor, where the coil lead connects, and then switch to earth. This has the effect of the points never opening. Over a long time the coil could get hot, but most thefts occur when you just leave the car for a short time.


Mick
M F Anderson

Has anyone tried the "Battery Brain" advertised in various magazines?

http://www.batterybrain.co.uk/

It's got two functions - one is to automatically disconnect the battery if the voltage drops too low so that you can still start the engine. The other, more interesting function is that using a remote control fob you can disconnect or reconnect the battery. It's £60, which is a lot more than a normal cut off switch, but also a lot more convenient!

As an aside, I have a trickle charger socket wired in via the HT lead to the starter - anyone know if the Battery Brain would interfere with this (obviously assuming I don't disconnect the battery first...)?

Cheers,
Tim
T Jenner

In my opinion, the best place to hide the switch is out in the open. For example, if there is a switch on the dash that is not in use then this would be perfect. A second choice is to add a switch that is similar in appearance to the others on the dash. I like the idea of having both the coil and the fuel pump switch with the fuel pump switch located on the dash.
Frank Grimaldi

I also have a battery cut off mounted on the heel board behind the drivers seat. Very handy for all the reasons given above and yes, you can take the key with you. It is fairly hard to spot when the key (which is bright red) is out.

On my old GT I had a fuel pump cut off switch that I also wired into the fuel gauge. When the switch was off the pump didn't work and the gauge would read empty.

If you're really worried you could always pop the bonnet and pull the rotor out of the distributor any time you park the car :)

Simon
Simon Jansen

To stop theft of a Ford Capri I owned I wired the coil to distributor wire to a Jack Plug socket mounted in the dash and used a jack plug wired as a loop to make the circuit.
Simply removing the jack plug prevented the car from being started. Ford locks in those days were rubbish and theft of cars was a big problem.
I know for certain my set up defeated someone after finding my car doors unlocked and the battery flat from some tealeaf cranking it over till he flattened the battery.
Jackplug fitted and jump start was less inconvenient than loosing the car.
C J Bryan

Lots of great feedback guys. I have a bit to think about. I am leaning towards both the coil and fuel pump.

I have done the distributor rotor before... but what I am after is something which is quick and easy which just becomes a habit with getting in and out of the car.

I hadnt thought of leaving it somewhere really obvious as on the dash. That's creative!

Keep that great info coming guys.

Mark
Mark Duggan

My next suggestion was going to be removing all the spark plugs but if you're wanting quick and easy, well....... :)
Simon Jansen

A super anti theft device was built into the T series cars and the MGAs. It is a fly off hand brake. It operates just the opposite of a standard hand brake - you have to push the button to set the brake! to release the brake, one just pulls up on it and releases it. the would be thief will spend several frustrating minutes trying to release the brake by pulling up ever harder while pushing the button only to find that the brake won't release. I use to witness this with great regularity when I was in high school and had a TD. Many of my friends wanted to drive the car (which I had been admonished no to allow) and I would tell them, if you can release the brake, you can drive the car - none of them ever drove it. The special tuning department made the bell crank pawl and a modified rod to convert the standard MGB hand brake to the fly off style. I have had several of the pawls made up and have converted the hand brake in our MGB. If anyone is interested in doing the conversion, I still have some of the pawls for sale (you will have to modify the rod to adapt to it).

Mark, I believe you said that you have an alarm system already installed in your car. Most of the alarm systems have an output that can be used to turn on a relay, which can be hooked up to your fuel pump such that when the relay is activated, it shuts off the power to the pump. Cheers - Dave
David DuBois

I have pictures of the normal and fly away style pawls here: http://www.asciimation.co.nz/pics/flyaway/index.html

I don't actually have one myself but have considered it from time to time. I was going to grind up a spare handbrake base plate to make the new pawl.

I am not sure they would actually be legal here in NZ actually? Might not get a WOF with one fitted?

Simon
Simon Jansen

Good point about the WOF Simon... Would certainly confuse anyone doing the check!

It would probably be ok if it was stock and was the original specs of the car... but if the car is non standard and is modified... Hmmmm... I don't know.

Mark
Mark Duggan

"but if the car is non standard and is modified"

One gentleman over here purchased an early MGB that had the fly off hand brake in it. When the cars were new The parts were available from the special tuning and competition department.

Simon - I think that it was you who sent me the pictures. I have had a second batch of the pawls made up and am selling them for $25 USD plus shipping. Cheers - Dave
David DuBois

I installed the late model ('77-'80, U.S.) steering column cowls on
my '71 B/GT. I got them for cheap at a local British car meet.

It has provisions for 2 switches but I found a pair of generic
black rocker switches that fit in he openings just fine. When
sitting in the driver's seat, the switches are positioned low, just
beyond the steering wheel - out of plain view.

I wired the fuel pump to one of the switches. It's fairly easy to
do as the hot lead to the fuel pump are right there near to the
ignition switch.

I figured that if somebody tries to borrow my car without
authorization, it'll run for a block or so...then sputter and die
in plain view of passers by, or, hopefully at an intersection
with a stop light camera, or a cop, etc.

This switch also comes in handy for keeping the fuel system
shut off when trying to service the electrical system (live) at
some other area of the car, or when spinning the engine to
build oil pressure just prior to firing it up after long storage.
Daniel Wong

I am considering the use of a cut-off switch similar to Simon (NZ) but I'm thinking about putting it in the driver's footwell. There is a 7/8" hole to the left of the steering column. Opening this out should be pretty easy. The advantages are it's well out of sight, being black when the key is removed helps, and the battery cable easily diverts to one side of the switch without cutting. I've yet to check if the engine bay side of the switch will foul anything.
Richard Coombs

Dave, I vaguely remember now. Was a long time ago! I sooooo need to get my car done!

I posted a picture over in the general thread about leather seat covers and just realised there is a good picture there showing my big red battery switch on the heel board behind the drivers seat if anyone wants to see where it goes.

Simon
Simon Jansen

Pesonally. I think an ignition kill switch, unless it is placed after the distributor, is a waste of time. It is too easily bypassed. On most Bs, you only have to short out the two bottom fuses to activate the ignition. I think the fuel kill switch is a better alternative. Unfortunately, this is easily forgotten by the driver & can cause problems. An easy solution is to use a double pole switch with the idle contact connected to a small high pitch siren, available from Radio Shack or similar.The active contact goes to the pump.If the car is hot wired, the siren will be activated,not the pump.This also acts as a good reminder that the switch is off. I've used a key operated switch mounted in full view. I couldn't find a double pole one, so I've incorporated a double pole relay.The pump supply lead feeds the input of the relay, the inactive contact goes to the siren & the active contact feeds the pump. The key switch provides 12volts (from the ign cct) to energise the relay. The result is the same as the double pole switch. Barrie E
B Egerton

Thanks Barrie.

I am now leaning towards the distributor rather than the coil. I will do this for the fuel pump also as a secondary backup.

Nice tip about the siren too!

Mark
Mark Duggan

Do not worry about the switch melting just don't wire the power circut through the switch, rather run a grounding circut to the points side of the coil use an old wire from an lbc harness make it look like it belongs not new and shiney. Getting back to the switch, I forget what the 67 used for a dip switch, on the floor or a column switch if its a column switch then the hot set up is to use a floor switch hidden in plain sight. Let us know how it works. Ric
RIC LLOYD

Use a panel mount, push-to-lock, use-key-to-unlock, 1/4" hydraulic non return valve plumbed into the hydraulic brake system. It can be neatly mounted below the dash and next to the door.
Just push the lock button before you exit the car and use the key (Yale/Union type) to unlock before you drive of.
If the car is "borrowed without your permission", and the foot brake is applied, the pressure is not release and the care becomes unmoveable. Alternatively, push the foot brake when you exit the car and all 4 wheels will be hydraulically locked until the non-return valve is unlocked.
The only way to move the car is by loosening or cutting a brake hose.
If you use ignition cut-outs, you must be able to lock and prevent entry to the engine compartment. If entry is gained, a simple jump lead from the battery cable to the coil and coil to the distributor and a push start is all that is required to wave your car good buy.
An external steering wheel lock is ok, but the spokes can be cut and the lock removed.
A gear lock is great (locks the gear lever in reverse), but a little liquid oxygen or nitrogen from a thermos flask and a gentle tap with a hammer soon shatters that.
Your car may be removed by a phone call to a brake-down service requesting them to deliver your "stranded car" to their address.
It's not easy keeping a car that someone else wants for nothing. All you can do is make it difficult for them and hope they go to an easer target.
Have fun.

Richard.



RH Davidson

power out off the cigarette lighter. New wire from lighter to the cont.breaker terminal . cigarette lighter in is no starting-----half cm. out is running. quick, cheap and easy!
wim

There is always the Mr Bean solution and remove the steering when when you exit the car too!
Simon Jansen

A pair of "vice grips" clamped on the steering column sorts out the "missing steering wheel" bit.

Richard.
RH Davidson

You can always buy a set of wheel clamps. That way it's VERY hard to move, steal or truck your car.

As a bonus you can never get wheel clamped or towed by parking wardens, either. Tickets are another matter...
Curtis Walker

If anyone is interested, I've just posted a review of the "Battery Brain" I asked about earlier - I ended up buying one and fitted it last week. See thread "Battery Brain review" on this forum.

Cheers,
Tim
T Jenner

When I reroute battery cable I installed also cut off switch that is hidden in passenger area (of course I have steering wheel on left side). It fits directly in hole of steering column so I didn’t have to drill hole.


Toni Kavcic

And from other side.


Toni Kavcic

grrr


Toni Kavcic

Pity it's not a 72 or later with the voltage triggered tach. With those a really neat trick is to wire a switch that connects an earth to the black/white trigger wire, and that shorts out the points. Jumpering the coil +ve to the fusebox is stage one in the scrotes bible and will bypass any ignition feed interrupt switch.
Paul Hunt

Good thing I read this thread before commenting.

Mick suggested exactly what I would do - ground the coil.

You can do it using an under dash switch, but thieves will look for that. Better to run a wire to an unused dash switch that does the same thing. On an MGA, the fog light switch is perfect - who would think that you can't start the car as long as the fog switch is pulled out?
Bill Spohn

When in America some years ago and borrowing a small Japanses 4WD of some kind we couldn't get it to start. Eventually somehow we did, then the owner said "Oh yes, you have to operate the turn signals before it will start". Apparently it was an immobiliser function that could be on almost any switch even on different examples of the same model, and I understand it was common at the time on various models and marques. Seemed an eminently sensible idea to me at the time, although these days alarms and immobilisers are mush more sophisticated.

"As a bonus you can never get wheel clamped or towed by parking wardens, either. Tickets are another matter... "

In the UK there have been cases of vehicles involved in an accident being ticketed, and even the ambulances and fire engines that attend them. Wardens have targets!
Paul Hunt

My solution on my 1970 B roadster (I was always leaving the keys in the ignition, top down, while parked in the city!) was to disconnect the steering column lock, and disconnect the ignition and starter wires from the ignition switch (not at the switch, but further under the dash, out of site) -- but leave the non-functional assembly intact in the steering column cowl, preserving the stock appearance.

I then wired the main ignition wire to a dash=mounted heavy-duty toggle switch, and the starter circuit wire to a push-button switch also mounted on the dash in plain site, but unmarked and in an innocuous position. (see photo below, the switches are adjacent to the speedometer & temp gauge.)

The result was that I -- or anyone -- could hop in the car and start it by flipping the ignition toggle switch on then pressing the starter button, without the use of an ignition key.

This might seem going in the wrong direction, but the plan was based on the "Hide in Plain sight" theory. A thief might get in the car and try to hot-wire it using the two disconnected wires, to no avail. No car thief is gong to carry a wiring harness schematic with him and take the time to track the wires, and who in his right mind would think that the method to starting the car was right there in front of him? A thief will move on to an easier target in these circumstances.

The MG was never stolen, in any case.


Paul Zink

Addendum to my post about the dash mounted ignition toggle switch and starter button: I also had a heavy-duty battery Kill Switch installed on the kick-board behind the seats, with a removable key.
Paul Zink

This thread was discussed between 15/06/2009 and 27/06/2009

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