Crazier New Reader
9/30/18 9:03 a.m.

I am doing a c4 corvette for the challenge.

I cant seem to nail down where the master kill switch should be? At the rear bumper? Drivers window? Near the cowl?

Help will be appreciated

boxedfox Reader
10/2/18 10:11 p.m.

If your car still has its stock ignition system (e.g. a key on the steering column) I would put the master kill switch on the passenger side, either near the A pillar or the B pillar. That way, a corner worker could reach into either of the two side windows and shut the engine off.

DeadSkunk PowerDork
11/4/18 11:41 a.m.

I believe the NHRA requires kill switches to be mounted at the rear of the car. The need for a switch is dictated by the car's speed and ET. If you're not relocating the battery from the stock location you don't need the switch.

SVreX MegaDork
11/4/18 12:56 p.m.

I don’t believe either of those answers are correct. 

As I understand it, the NHRA requires a master kill switch ANYTIME a battery is relocated, and that it must be at the rear of the car. 

Mandatory when battery is relocated, or as outlined in Class Requirements. An electrical power cutoff switch (one only) must be installed on the rearmost part of each vehicle and be easily accessible from outside the car body. This cutoff switch must be connected to the positive side of the electrical system and must stop all electrical functions including magneto ignition. The external control switch for this cutoff switch will be clearly indicated by a red flash inside a white-edged blue triangle with a base of at least 12 cm (see drawing 25). The positions must be clearly indicated with the word "OFF". If switch is "push/pull" type, push must be the action for shutting off the electrical system, pull to turn it on. Any rods or cablesused to activate the switch must be minimum 1/8-inch (3.2 mm) diameter. Plastic or keyed switches prohibited. Switches and/or controlsmust be located behind rear wheels on rear engine dragsters.

Perhaps someone more familiar with the NHRA can chime in. 

DeadSkunk PowerDork
11/4/18 2:02 p.m.

I was intending to say the same thing, but it does leave some ambiguity.  As I understand it, you can go without a switch if the battery remains in the stock location AND the car doesn't exceed the speed or ET limitations, whatever they are. As soon as you relocate a battery a switch becomes mandatory, at the rear. Where's Andrew when we need him?


bearmtnmartin SuperDork
11/4/18 2:47 p.m.

I always put them where first I, and second a turn worker can reach on the premise that I will be first at the scene of the accident and I would rather not have to wait for someone else to finally show up and kill the power for me.

DeadSkunk PowerDork
11/4/18 3:03 p.m.
bearmtnmartin said:

I always put them where first I, and second a turn worker can reach on the premise that I will be first at the scene of the accident and I would rather not have to wait for someone else to finally show up and kill the power for me.

That's what I did with my road racing cars, but NHRA seems to be different from what I've found so far. Nothings says you can't have two switches , or remotely operate one with a cable.

SVreX MegaDork
11/4/18 4:27 p.m.

In reply to bearmtnmartin :

I don’t think a master kill switch is for the driver. The driver can kill the car with the ignition, etc. 

The kill switch is for the first responder course  workers. 

Crazier Reader
11/4/18 5:15 p.m.

I moved the battery... I left enough wire to place the switch anywhere in the rear so that i can make a decision later.

I also ran the alternator charge wire all the way back to a direct connection on the battery.

It is a very good thing i am not buying wire by the foot!

frenchyd UltraDork
11/4/18 5:25 p.m.

In reply to Crazier : NHRA has it in one location. SCCA has it in another. Champcar in the third.   I think LeMons differs from Champcar and the rest of the clubs I don’t know about. 

From a practical safety standpoint it should be in easy reach of the driver when he is belted in his seat yet where a track worker  can also reach it.  

Plus there is the whole wiring issue.  If the car has an alternator it needs to be wired to protect the diodes while shutting everything off.  


SVreX MegaDork
11/4/18 5:40 p.m.

In reply to frenchyd :

Sorry. I disagree. 

Crazier said he is building a Challenge car. The Challenge takes place at Gainesville Speedway- an NHRA track. 

He needs to build to NHRA safety specs. It’s their insurance, and their tech inspection. 


Crazier Reader
11/4/18 7:06 p.m.

If i crash., or catch on fire im not going to worry about the alternator.

I've yet to figure how to wire it the corect way. The kill switch will only be hooked up at the track, and i can prep several lengths of wire and a couple mounting points and then i can swap depending on tbe track?

SVreX MegaDork
11/5/18 4:40 a.m.

In reply to Crazier :


You never actually said you relocated the battery. Is a kill switch necessary??

I don’t think a “mobile” kill switch addresses the problem. It might make it worse. The kill switch is to shut down electricity in the event of an emergency. The implication is that after-market wiring to relocate the battery has a higher risk level than OEM wiring. 

A “mobile” kill switch would only add more loose after-market wiring, and more risk. 

Don't add one if you don’t need it and if you do, add it in accordance with the rules of the venue you are running at. 

Crazier Reader
11/5/18 11:22 a.m.

I did relocate.

Ive rewired the entire car.

The only difference in the wireing from one location to the other is the length of the wire from the switch to the battery. And from the switch to the "main lug"

Remove a length of wire 1.5 feet long attach one 3 feet long. Move the switch and atrach it firmly.

dhof New Reader
11/18/18 4:37 p.m.

Double check the rules as well as any other sactioning body you plan on attending. When i did w2w they wanted it where the driver and corner work could grab it. If you can swing it near the drivers window in the dash or rollcage os typically accepted. 

Crazier Reader
11/19/18 6:52 a.m.

Yeah. I think i will have to just make multiple mounting points and wire lengths. Probably leave a few extra wire hangers mounted as well.

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