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I have a question that I have a feeling will tickle someone's creativity bone. I just ordered a speedster from VMC and am wanting to install a kill switch.

Here are all the ideas I've seen float around:

1) pop the hood and disconnect the battery after each use

2) purchase a marine kill switch with a red key that essentially does "1" but easier

3) install a fuel cutoff valve somewhere that is covert, yet easily accessible along the fuel line

4) install a 4-prong (may be incorrect verbiage) cutoff that will render the battery useless, but also leave the coil and fuel pump without power from the generator/alternator (eliminating the option to "bump start").

I know this is overkill (pun very much intended), but it's just for fun and to explore something with which I am 100% unfamiliar.

Hand drawn diagrams, overblown explanations, and jargon filled rants are not only welcome (I know I do this silently all the time), they are encouraged.

Last edited by JoelP
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Most likely your car will have an electric fuel pump - use a toggle switch to cut power to it.  Car can be stolen and driven maybe a 1/4 mile before fuel in line is used up.  An inline fuel cut off is a good idea if you do plan to store car for any period of time - some carbs seem to overflow if car is parked on incline too so that prevents that too. These are available from ACE HW for lawn tractors.

I have the switch Ray posted. I have it installed in the battery ground cable. The cable goes from the battery to the switch and then from the switch to a bolt in a nearby drilled and tapped hole.

On my CMC, installation did require drilling through a thick piece of steel.

20200208_171114

That’s how I’d do it, too, now that I’ve relocated my battery up front.

Michael, what are the odds that switch could spark? Kind of wonder as it’s right under your gas tank.

Here a strictly hypothetical security circuit that puts a small, low amperage, single pole, single throw, toggle switch under the curl of the dashboard. You can hypothetically learn to find the toggle switch easily as you turn the ignition key off or on, hypothetically. The miniature toggle switch is rated at 5 amps at 125 volts but only carries the relay coil load (.15 amps at 12v).

The toggle switch grounds a power relay located in the wheel well or under the nose. The power relay is rated at 200 amps and when grounded, switches power from the battery to the main harness.

This setup performs just like the switch noted by Ray and Michael above, except that it is enabled or disabled by the hidden, miniature, toggle switch under the dashboard. It would be a cinch to have Greg pull a wire from the battery area to the dash area while the car is being built.

I would prefer the left side of the dash, hypothetically, of course.Security Circuitswitchrelay

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Last edited by Michael Pickett

if a thief wants sumthin' bad enough....it's gone!...just sayin'....that being said...in the mid 80's my cousin witnessed this scenario....i guy with a 70's 911 RS was cased by car thieves were he got coffee each morning....they lowered the roll off ramp on the truck around the corner and the owner watched this team roll around the corner...a guy jumped out ....quickly had a cable with a hook ...attached the hook under the front......and with out stopping the truck...dragged the car down the street with the winch onto the ramp ....lowered it down and adios!!....all before he could run out the diner door....so, even with a kill switch/fuel pump switch etc in a speedster/convertible (gotta break windows in a coupe,but that's done quickly as well)....if you aren't guarding your car....the pro  bad guys can pop it in neutral , release the hand brake and push it to said roll off truck pretty quick...i just carry a "CLUB" steering wheel lock.....which is a pretty good overall solution.....not sure, but i bet not many of our replicas get ripped off.... the pro thieves are probably more interested in the REAL DEAL multi $6 figure cars.... al that said...happy theft-free motoring

I worked on a Spyder last summer that had the red key battery cutoff behind the driver seat. Take the key with you and good luck trying to bypass it.

I have to say it was VERY convenient to work on and weld on the car.

Having said that I'm with @jncspyder. If the thieves want it, they're gonna get it no matter what tricks you have. With a rolloff, it's gone in a minute or two.

That's what insurance is for.

Last edited by DannyP

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@JoelP , the real question is WHY you want a kill switch.

Completely disconnecting the battery is convenient for working on the car's electrics. But for that you need a big honkin' switch, usually made just for the purpose, that can handle lots of amps. (Did anyone notice the Jersey apostrophe?)

If you've got an electric fuel pump, it's probably a good idea to have that on a dedicated switch no matter what, so you can turn it on before startup to fill the float bowls if the car's been down for a while. Or turn it off in the event of a major conflagration.

But if all you want is theft protection, the simplest thing is a hidden toggle switch under the dash that interrupts power to the coil. Even if you don't use a relay, current load in this circuit is pretty low, so a moderately-rated switch (say, one amp) will suffice. This is the 'kill switch' the old VS used to install if asked and, not surprisingly, it's the most economical of all solutions. Power to the coil comes from the ignition switch, so installing this kill switch nearby is pretty simple.

This can also be helpful starting a cold engine that hasn't been fired in a few weeks in cold weather. You can crank the engine for a little bit without it firing to get some oil circulating after it's all mostly drained into the sump.

This begs the question of whether any anti-theft measures are prudent on our cars, since, as suggested above, the pros want the real deal and the little guys want parts they can chop and fence. Also, it's way harder to blend into traffic in one of these than in, say, an Accord or a Beemer.

And the demographics of today's car thieves being what they are, a kill switch is probably less of a deterrent than a clutch pedal.

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Easiest is to kill the fuel pump relay power with a hidden kill switch, or better yet 2 hidden kill switches in different locations.  Main battery kill works well too, but best for aircooled and not watercooled (with stock ECU anyway).  In the end, something like a battery kill switch will keep the honest crooks out of it, the joy riders, or whathaveyou...  a real crook or someone with knowledge of what they are doing can bypass a battery kill in about 10s.

One thing that tends to be overlooked is a locking engine deck lid. One situation I know of,  a set of Dells that were stolen off a speedster while it was parked overnight on a transporter's trailer. A locking deck lid would help in keeping prying eyes and fingers out of the engine bay . One can hot wire a speedster with a jumper from the b+ alt to coil +,  pop the clutch in under 30 seconds.

Geez....  Bob and Mike are gonna have us reading "Eats, Shoots and Leaves", next.  

(Notice, an Oxford comma would not be appropriate there).

I'm still undecided on when to use a colon versus a semi-colon, but I'm workin' on it...

Kathy packed up my copy of E,S&L with other books we donated to the local library.  I had to race over there and beg it back, just for times like this.  

(did anyone notice the oxford comma?)

I did, and I appreciate it.

@Robert M posted:

I didn't know what it was called so I looked it up. I have always used one, it was the way I was taught.

Me too. Mrs. Evans would have it no other way.

@Sacto Mitch posted:

(Did anyone notice the Jersey apostrophe?)

You had me at big honkin', Mitch... although if it was actually "Jersey", I don't think the word you would use would be "honkin'".

I'm still undecided on when to use a colon versus a semi-colon, but I'm workin' on it...

Ah, the semicolon.

The rules for it's use are straightforward. But the thing is - nobody uses them anymore. Like NOBODY nobody. Read the WaPo, or NYT, or WSJ, or The Atlantic  (writers working in places where people can write). Nobody uses them, ever, for any reason.

I had a boss (back in the day) who beat it into me in no uncertain terms - no semicolons for any reason. I thought he was an idiot, because I knew how to use them. Then I started reading what people in the 20th century were writing.

The semicolon is dead. Long live the semicolon.

Last edited by Stan Galat

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@Stan Galat posted:
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...Read the WaPo, or NYT, or WSJ, or The Atlantic  (writers working in places where people can write). Nobody uses them, ever, for any reason...





Well, yeah, it's not like them dudes (okay, okay, those dudes) are so in touch with how smart people speak today. It's more like their editors correct everything they type to conform to the rules in the AP Stylebook - an actual book published by the Associated Press.

I think this goes back to the days when the AP wrote a lot less of its own content, but distributed to member papers stories from other member papers. AP is technically a 'cooperative'. Papers aren't clients, they're 'members'.

So, you couldn't have a thousand editors typing on a thousand typewriters at a hundred different newspapers and expect to end up with any consistency of usage. The AP attempted to bring some order to the chaos by publishing its own book of rules that everyone would follow and that has been adopted as a sort of industry standard reference.

This way, you don't have to remember what Mrs. Gewurtztraminer taught you in the fourth grade (is it 'lie' or 'lay'?), you just look it up in the blue book.

The book covers everything, and I mean everything. I have noticed that Ed ( @edsnova ) will occasionally toss in an em dash just to prove that he knows the difference between that and an en dash and a hyphen. He probably doesn't really remember, but has a copy of that damned blue book somewhere.

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