What's the cleanest way to wire a cut off switch

[magnumdust]

While i'm doing my re-wire i figured it wouldnt be a bad idea to do a rear mount battery, which i'm told needs a cutoff switch to pass tech at the tracks.


Also, i see a lot of setup's cut the alternator, could one accomplish the same thing if they switch cut the ignition system? It *seems* like that might be easier to wire.

 

[TrailBeast]

If I'm not mistaken the rules require a switch to disconnect the entire electrical system from the battery.
They call it a battery disconnect and they come in a ton of different designs that only some of are approved for tracks.

 

[805moparkid]

cut and dried way to go.

run the positive thru the switch and to the starter

from the starter run a 10ga wire to the starter relay post (this feeds alt power to the battery)

cut the VR feed wire in half (from un-resisted side of ballast resistor)

the bulkhead side will be routed to one of the small posts of the switch

from the switch run another wire and connect to the other half

what this does is:

cuts main battery voltage from the switch forward

and

cuts power to the VR using the switch which prevents run on.

for this to work you obviously need a 4 post switch (two large and small) but is the easiest way to go, no relays and BS to wire...

 

[67Dart273]

cut the VR feed wire in half (from un-resisted side of ballast resistor)

the bulkhead side will be routed to one of the small posts of the switch

from the switch run another wire and connect to the other half..

Disagree

I DO agree you SHOULD get a 4 post switch (properly known as a DPST, which means "Double Pole Single Throw)

I DISAGREE not to run a relay. The VR wire is the voltage sense wire as well as the power supply to the VR. A long run of wire all the way from the VR, back to the switch, and back to the original ignition buss introduces voltage drop and will cause an overvoltage / overcharge condition.

Using a relay (or continuous duty solenoid) up front to supply switched ignition loads, including the VR supply, removes this problem,

 

[HotLines]

My cutoff is to the left of the drivers seat as seen here, barley visible and the next photo is how it ties into the battery cables.
This photo shows the bottom and how it ties into the battery cables from the battery and straight forward

 

[67Dart273]

My cutoff is to the left of the drivers seat as seen here, barley visible and the next photo is how it ties into the battery cables.
This photo shows the bottom and how it ties into the battery cables from the battery and straight forward

How does that pass NHRA? Or is your battery still up front?

 

[HotLines]

The battery hasn't been up front since it was owned by the old woman before I acquired it and was stock. I haven't a clue to NHRA rules today and to tell you the truth, they never said anything to me when I raced this Signet back in the 90's. As of today it is still in the Signet and NHRA means nothing to my daily driver

 

[67Dart273]

The battery hasn't been up front since it was owned by the old woman before I acquired it and was stock. I haven't a clue to NHRA rules today and to tell you the truth, they never said anything to me when I raced this Signet back in the 90's. As of today it is still in the Signet and NHRA means nothing to my daily driver

Well since the OP mentioned this, HE has to pass NHRA. If the tech guys didn't catch yours, it's because they didn't LOOK or ask

i'm told needs a cutoff switch to pass tech at the tracks..

 

[HotLines]

Well since the OP mentioned this, HE has to pass NHRA. If the tech guys didn't catch yours, it's because they didn't LOOK or ask

I can not understand what could be better than this installation of a race cut - off switch which uses OT size cables running the length of the welded in sub frame connectors as well as both sub frames being held on with metal and rubber cable holders screwed on. The installation is clean and no where near any heat or substance which can create a problem. The cut - off switch itself is a bonified race cut - off switch sold by many companies today. The upper end of the switch is easy access for the driver in case of an accident of any kind. It's been this way for many years and never a problem..

 

[67Dart273]

I can not understand what could be better .

Well you might actually try reading the RULES

This isn't about you or what you have done. It's about the OP who wants to be able to show up at the dragstrip.

The battery must either be in a metal box vented to the outside, or a metal box / sealed battery. If not a metal box, must have a sealed all metal firewall behind the rear seat.

Switch must KILL THE ENGINE (which yours does not do)

Switch must be in the positive cable

Switch must "kill all power"

AND it must be easily accessible at the REAR of the car. A push-pull switch MUST shut off by PUSHING, and not pulling.

The reason for the double pole switch is that if you have the engine running --on a car with an alternator --and you yank your switch open, the engine will keep right on running on the alternator.

From the 2012 rulebook

 

[magnumdust]

Well since the OP mentioned this, HE has to pass NHRA. If the tech guys didn't catch yours, it's because they didn't LOOK or ask

Its not that i necessarily need to pass NHRA, i just need the car to be track legal for wednesday night drag races

 

[805moparkid]

Its not that i necessarily need to pass NHRA, i just need the car to be track legal for wednesday night drag races

one and the same...

its not about the driver, its about the ability of the safety crew to kill the vehicle when your unconscious and upside down and possilby on fire because your fuel pump is still running...

 

[younggun2.0]

mine is so clean that i had to put scrubs on when i installed it. lol.








I just finished a complete re-wire with a painless kit. i have a 4 post switch. the big wire is from battery to starter only. then i have a 4 ga. wire that feeds my fuse box. my alternator is wired to the voltage reg. then i have the charge wire going to the starter post. my alt is completely isolated. when i kill the switch it cuts all power to the car from the switch forward. everything is killed.

 

[HotLines]

Actually my switch does kill the engine as well as all electrical and my battery does sit in its own box and only the positive cable is used. The switch is not on the outside as that wouldn't help should anything occur during a run or a drive. I do have the on-off plate though I do not use it.

Sorry it's not up to par for the NHRA but at least I do not have to cut a hole in it's beautiful sheet metal outside of it's trunk to appease others while still knowing how my car runs whether on the street or at the track. I guess I am just not ready to impress others as I am only into it for the money and not trophies..

 

[805moparkid]

Actually my switch does kill the engine as well as all electrical and my battery does sit in its own box and only the positive cable is used. The switch is not on the outside as that wouldn't help should anything occur during a run or a drive. I do have the on-off plate though I do not use it.

Sorry it's not up to par for the NHRA but at least I do not have to cut a hole in it's beautiful sheet metal outside of it's trunk to appease others while still knowing how my car runs whether on the street or at the track. I guess I am just not ready to impress others as I am only into it for the money and not trophies..

who said anything about impressing others? i race slants so i know about doing thing different but having the switch outside on the rear is a safety reason not fluff.

 

[HotLines]

MoparKid, you are correct in regards to the chicken but did you know that The rooster has a Cloaca, not a *****, which transfers sperm to the hen. The roosters testes are located high up in the abdominal cavity along the spine.
When mating the rooster inverts his cloaca to touch the hens cloaca and transfers a sperm sac containing enough semen for about 10 days worth of fertile eggs to be produced.

As far as hot rodding is concerned, " anything goes " It's only purists who haven't an imagination. Having an imagination is why we have electricity today, having the money is why Fiat owns a big part of Chrysler and imagination is why Daimler walked away...

Have a nice day

 

[805moparkid]

MoparKid, you are correct in regards to the chicken but did you know that The rooster has a Cloaca, not a *****, which transfers sperm to the hen. The roosters testes are located high up in the abdominal cavity along the spine.
When mating the rooster inverts his cloaca to touch the hens cloaca and transfers a sperm sac containing enough semen for about 10 days worth of fertile eggs to be produced.

As far as hot rodding is concerned, " anything goes " It's only purists who haven't an imagination. Having an imagination is why we have electricity today, having the money is why Fiat owns a big part of Chrysler and imagination is why Daimler walked away...

Have a nice day

](*,):violent1: i hope a safety team never has to save you by using that switch...

 

[younggun2.0]

MoparKid, you are correct in regards to the chicken but did you know that The rooster has a Cloaca, not a *****, which transfers sperm to the hen. The roosters testes are located high up in the abdominal cavity along the spine.
When mating the rooster inverts his cloaca to touch the hens cloaca and transfers a sperm sac containing enough semen for about 10 days worth of fertile eggs to be produced.



AHHHHH, but what came first? the chicken or the egg?

 

[HotLines]

Moparkid, I probably been drag racing NHRA since before you were a twinkle in your parent's eyes and am very safety conscious as well. I no longer partake in activities you seem so wrapped up in yet when I was, this passed inspection. In the past, the rules and regulations of the NHRA is one of the reasons IHRA started. Yet as of today, my safety cut-off switch is directly next to my seat and if something happened I am sure I would be the first one on the scene, so in your eyes maybe two switches would fit the bill. Never the less I no longer compete. when I was 17 in 1961 I drove a fuel dragster and in 1967 I joined the 200mph club at Pomona, Those days are gone for me and street cars are what I am into at this time of my life. Maybe one day we'll hook up and laugh at all this crap.

Have a nice day

 

[67Dart273]

Moparkid, I probably been drag racing NHRA since

Just because you've been doing something for XX years does not mean you have been doing it RIGHT. I have posted the NHRA relevant section. If you have "passed" inspection with this, it's only because the tech guys did not LOOK.

Please stop with your meaningless arguments on this matter. The OP clearly said that he wants to show up at a racetrack. If he does, he needs to do this correctly so that if and when a tech guy actually LOOKS at the car and TESTS the switch, the damn thing actually meets the rulebook.

Your statement that your switch kills the engine is NOT correct, if you run an alternator. This is not opinion. This is a fact of physics

For your edification, the first time I showed up at a racetrack was 1963.

 

[805moparkid]

Moparkid, I probably been drag racing NHRA since before you were a twinkle in your parent's eyes and am very safety conscious as well. I no longer partake in activities you seem so wrapped up in yet when I was, this passed inspection. In the past, the rules and regulations of the NHRA is one of the reasons IHRA started. Yet as of today, my safety cut-off switch is directly next to my seat and if something happened I am sure I would be the first one on the scene, so in your eyes maybe two switches would fit the bill. Never the less I no longer compete. when I was 17 in 1961 I drove a fuel dragster and in 1967 I joined the 200mph club at Pomona, Those days are gone for me and street cars are what I am into at this time of my life. Maybe one day we'll hook up and laugh at all this crap.

Have a nice day

Mark crashed his lancer at 100 miles an hr about a month ago. he said he saw a wall then the other wall and then another and then hit. he dosn't know if he was there for 10 seconds or ten minutes, my point being is you might not even know your name when you need to hit that switch, and beign part of the 200mph club should have you more strict, not less.

And Yes im all about the match bash!

 

[HotLines]

My time was irreverent alright as well as nhra national record holder in the mid sixties for AA/MSP " Instant Motion " Dodge powered Cheetah.

Sorry I am no help to the poster's question yet at least I haven't any negative statements as well... I always wondered what it felt like to be perfect, can both the kid and 67Dart273 explain what it's like?

 

[Revhendo]

Ya know, they used to say the earth was flat. Might just be in certain parts of Oregon.

Magnumdust, Dart and Kid got it right. Go with what the rulebook says and you'll not have any problems with tech which is what I'm inferring from your original post.

 

[67Dart273]

My time was irreverent alright as well as nhra national record holder in the mid sixties

You sir are (except for spelling errors) exactly correct. "irreverent" only you meant "irrelevant" to the present question. The rules today, in 2013, say what they say. What you "did" in 1966 is not what the rules say today. Nobody's making fun of what you "did." What we are saying is, it's different NOW.


Hell I can remember "Saturday night" track there pretty much WAS no tech. I didn't even realize that I was supposed to be running a driveshaft loop until a friend pointed it out. The "tech" guys simply never LOOKED

 

[Revhendo]

Oh and heaven forbid should you get it crossed up and cause injury to someone else these days. Your car will be picked to death and if something ain't right, guess who's on the line.