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Discussion Starter #1
I don't understand the obsession with battery cut-off switches in these cars. Is it a 'race track' requirement? Or, is it just a cool gizmo for the blond in the other seat to ask, "What's that do?". Most cars on the road do not have one. The safety case, in my opinion, is marginal. I don't really plan to do much 'race track' racing, however, the idea of a blond in the other seat is appealing!
 

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I think it started out being important when the battery was mounted underneath and inaccesible. I may be required for racing but I think it needs to be accessible from outside the car to be legal.
 

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It's also a great anti-joyride device. It is real peace of mind when you want to leave it out of sight for a while. They can key it, spit on it, or rip your emblems off, but at least they cant steal it and wrap it around a tree.
 

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Hi,

I installed one for two reasons. I like the idea about being about to turn the battery off completely. I was obsessive about my short postitive battery run from the battery to the switch so I know that if the key is with me,

1. There is, for all reasonable purposes, no chance of an electrical fire.

2. It's another layer of theft protection.

HTH!

-R :D
 

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And the REAL reason is...."Whats that?" Well, its a...
 

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Instead of tying my battery cut-off switch to the battery, I used it as a kill switch for the electric fuel pump. For a few reasons:

1. Yes, as a theft deterent. You have to break into the trunk to bypass it.

2. A safety fuel cut-off switch when racing or during and accident to shut the fuel off from flowing to the engine.

3. And yes, it looks cool...

But, if you install it as a battery cut-off, be very careful to never kill it when the car is running. It happened to a friend of mine when he was taking a little kid for a ride. The boy turned the knob and fried the MSD box. I guess the firing of the motor when it was driving sent a current back to the dead ignition box. Bad, very BAD!!!

Good Luck, JUSBIT
 

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FFCobra Master Craftsman
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Well, my battery cutoff switch would've prevented this alternator fire IF I'D TURNED THE DARN THING OFF!


If you're using Ford's Fox-era alternator and factory alternator wiring, install a battery switch and turn it off when you're not driving. Just my opinion.
 

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I hope I'm not the only one that used one just because I screwed around so much with the wiring in the car, that no matter how safe I try to be I always feel like there's an electrical short just waiting to happen. Then again, I might very well just be paranoid. Plus, if I only build a car once in my life (which I hope isn't the case), I love the idea of putting in enough switches to give the driver all the control over this awesome machine that he can get. And yeah, of course some people, myself included, think it looks cool... but that's all secondary to the fact that the wiring just wasn't done by a professional, and I want something to stop the juice flowing in an emergency.

Oh yeah, and just having the cutoff available while I build the car is reason enough for me; I don't want to have to pull the terminal off the battery every time I leave it for the night, and it's a convenient way of stopping the battery from draining if I leave something on by accident.
 

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Because I have absolutely no confidence in my wiring ability and because our bedroom is above the garage.
 

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I think Marshall (and of course John Phillips ;) ) have the best reasons of all. Using it as a theft deterant really isn't that practical since a lot of the ricer guys also use those cutoffs, and the "keys" are generic!
 

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Partly because it looks cool. And the above mentioned safety reasons. But as you build and work on the car, there are a lot of times when you want to turn the power off and on, and the switch is real handy for that. It's so handy that I put one on my '66 Mustang.
 

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Instead of tying my battery cut-off switch to the battery, I used it as a kill switch for the electric fuel pump. For a few reasons:

1. Yes, as a theft deterent. You have to break into the trunk to bypass it.

2. A safety fuel cut-off switch when racing or during and accident to shut the fuel off from flowing to the engine if you happen to have an elect. fuel pump.

3. In case of long term storage it's easy to disconnect.

4. If you do an indoor car show you are required
disconnect the battery in California.

5. And yes, it looks cool...
 

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I have a less disasterous story than John P, but it inspired me to research and install mine.

I was driving around with a friend one day, an hour from home. We noticed a little whisp of smoke that looked like it was from the back of the hood. We both quickly popped open the hood, him with the fire extinguisher at the ready. Nothing. Hmm. Fine for the rest of the ride. I then drive an hour home. Pull in the driveway and a huge cloud of smoke comes from under the dash. I mean huge. I reach under and yank on wires in the general area. I then get out and jack up the back of my car, take an adjustable wrench and pull the bolt off the ground to frame connection. Subsequently, I find that the ammeter nut had worked loose and that the battery + was basically shorted to the case of the meter. The padding and vinal of the dash insulated it from the aluminum dash, but the illuminator light ground wire was not so lucky. Fortunately, I had used a single, small wire to go from that to a single screw ground on the frame. The wire took a dead short until it fused open.

As a result, I did 3 things. I removed the ammeter, engineered, built and installed a battery tray over the passenger side footbox and put the battery there. The ground terminal is inside the body work and + terminal exposed in the engine compartment. I then ran the wire from the fusable linked alternator line directly to the battery. The battery + now goes to a cutoff switch on the tranny tunnel upright and then on to the rest of the car.

Although I'm fairly confident in my wiring knowledge and work (I have a graduate degree in EE and 20 years in power supply design) I still know that I haven't tested this car/design in the 100's of hours of testing that the production automakers put their cars through. If something goes wrong with my 4 year old in the passenger seat, I want an out that's a better option than getting him out as quickly as possible while the car burns down. The cutoff switch in this location does this for me and is easily accessible from inside or outside the car.

I leave the key of the switch in place at all times, normally.....and carry a spare on my keyring in the unlikly chance that someone wants it as a souvenir.
 

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John P.,

I am sorry to see your loss. I hope no one was injured (physically). Did your insurance cover the loss and are you carrying on with a new build?

Best of luck,
Kieran
 

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Kieran, Thanks for the kind thoughts. #1152 burned up in February, 2002. I started building a replacement FFR, #3422, in March 2002, in the rental house we moved into while our home was rebuilt from the fire. It's a long wonderful story, but the short version is that Dave Smith of Factory Five furnished the new Mark II kit, a ton of FFR friends all over the USA/Canada furnished help and encouragement, I bought parts from almost every vendor on the forum, ~25 helpers came for a weekend build-party to get me started, and the car was done and being streeted and raced by July, 2002. I drove the heck out of it (about 13,000 miles) until last February, when a local FFR enthusiast approached me to buy it. I sold it, intending to play with an older M3 for awhile, but missed building and running my own car, (and I kind of wrecked the M3), so bought #1004564 last fall during FFR's "Red Sox World Series Win" sale. This build is going much slower, using some new 4.6 technology, but definitely will have a battery cut-off!

If you're interested, there's more detail about this whole story at the website in my signature line. No one was hurt, thank God, but it took 13 months to repair the damage. State Farm paid out a fortune to make us whole. We moved back in about March 2003. Sorry, looks like I got wordy here...BE SURE TO USE YOUR CUTOFF!
 
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