Remote kill switches

[Tim Royer]

HI all,

Look either way it is hooked up it will work. A kill switch that is on the negative side cable has one other advantage then positive side. The positive side from the battery terminal all the way to what you have it connected to, like the starter (GM) or solenoid (FORD), will not be able to arc if grounded out because there is no ground when that switch is thrown. There is no ground to anything not even the battery. Then it is not possible for the positive wire, or any other "hot all the time" wire to arc, you have no ground. You could take a screwdriver against the body and touch the positive pole on the battery and nothing will happen. Try that with putting the switch on the positive side.

Steve your explanation would be correct if you switch the terms positive to negative. That's exactly why you want to use negative side.

And use a switch with alternator circuit switch if your running an alternator.

Production formula cars and any others I have seen all have the negative cable run the switch.

I guess I'm not good at explaining in writing, see me after class

[Matt Green]

Yeah, except for the fact that it still won't kill the iginition in a car with an alternator...

Dick does have the best way to do it if you only have a 2 post switch.

Oh, and Steve is exactly right the way he is. He's saying that when the wire gets crushed and shorts somewhere in between the battery and the switch, it will complete the circuit even if the switch is off. Think about it.

And yes, it does happen.

[Tim Royer]

And use a switch with alternator circuit switch if your running an alternator.

That should be a no brainer.

6 post $8 more and done right.

[Matt Green]

What if you're a guy running a GM style one-wire alternator? Those extra posts are for the field control (low current), and that's all internal in the one-wire.

And don't go saying it's only a GM thing, because I've seen a lot of them on ALL types of cars (including Formula cars...)

[Tim Royer]

Hi,

I have a one wire on the Gurney matter of fact. All it does is break the positive wire off the alternator. The switch I have is heavy-duty continuous use, not light duty. There are different switches out there watch you don't get one that is limited use.

[Matt Green]

Oh BTW- with all this bickering, we've strayed from the original question.

Dan- check out the link below to see a possible solution that would accomplish one of the things you desire.

http://www.nogumracing.com/karl/integra/killswitch.html

You could then run an alternate cable within reach of the driver too...

Disclaimer- I do not endorse this method, I was merely trying to offer something to think about...

[Rich Sweigart]

Excellent link on the subject.

http://www.users.fast.net/~nescca/tech.html

If that doesn't work try http://www.nescca.com and click on tech notes.

Rich

[drhyne]

Thanx everyone I think I've come up with a solution. Looks like I've also created a monster.

FYI Tim. In the DSM cars a negative kill won't work. There's now way to disconnect the ground on the alternator. In most cases a fuse at the source will eliminate the chance of a spark. The cable pull is a good idea but still a failure point. I don't think it has to be this complex.

The Painless solenoid appears to be the safest route. Any break in the control wire causes shutdown. It allows you to put kills wherever you want. It also has the shortest amount of HOT cable. The only thing I would add is a constant lead for my ECU with a tiny fuse.

These solenoids have endless posibilities. I've read article where they have been hooked up to everything from G-sensors to oil pressure guages. Just a thought for the open minded!

Oh and a MANUAL fire pull. Why add complexity!

D_.

[ryotko]

Hey Dan,

If you're worried about the fuel pump running after a crash what about an inertia switch. It can be used in addition to a master kill switch but it will shut off power to the pump if you can't. See below.

-Bob

http://www.pegasusautoracing.com/Produc ... p?RecId=87

[TAMNOZ]

Jeff,
There was a thread like this on Wheel to Wheel a couple years ago and I got my self in trouble because I spoke to loudly. The fact of the matter is that Master Kill Switches are not put there for the driver, they are put there for the safety workers. There for it is best to put on the right cowl or just inside the Pass. door on the rollcage to give contiuity to all production type cars.
Jim Oswald

[JekylandHyde]

Jeff,
...
Jim Oswald

Hey Jim,

Is there another Jeff in here or did you mean to address someone else?
I don't think I was participating in this thread until now.

don't mind me, just confused by the "jeff"

[BillStrong]

Good find. Personally I think these should be manditory.

http://www.pegasusautoracing.com/Produc ... p?RecId=87

There is also a switch that shuts off the pump if oil pressure drops to zero, or some low number. I have a Moroso version from year ago that works well.

[mckee]

I agree with Tim that the ground circuit should be broken to reduce the chance of sparks, but the alternator requires the positive cable to be opened.

I use a 4 pole switch ($39): One pair of poles cuts the negative cable while the other pair cuts the alternator off. There is no connection in the switch proper between the 2 pairs. Both I and a safety worker can reach the switch that is roll bar mounted.

I also use a punch button master switch on the dash that cuts off ignition and electric fuel pump. If you've ever had a throttle stick you'd want one.

Finally because I'm scared of fires I run my electric fuel pump ground through a 5 psi Hobbs switch ($7) screwed into an oil galley. If the engine stops, so does the fuel pump -- no matter what I'm doing or not doing.

[Tim Royer]

Zzactly!!