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I'm in the process of relocating my battery to the rear with a cutoff switch. I've relocated the starter switch to the inner fender and it looks much cleaner in the bay. I'm currently running 4ga monster cable to the switch on the battery side with an inline Stinger 125amp fuse. Can I use the same size wire to send it to the back on the cutoff? I hear of people using 1ga and 2 ga for the main wire to the starter switch and 2 ga to the alt. I was thinking of running 2ga welding cable to the switch and 4ga welding cable to the alternator. Will this work fine. I know the ratings on the wire from Smithmonte's site and I have the diagram from Boffhomers site. I'm just wondering if 2ga is adequate for charging when used in that length?

Also, for those who race with a battery in the back, Do you have your battery bolted to the framerail or just through the floor? I thought it was supposed to be to the framerail but hear many people talk about it going through the thin flooring with a support bar underneath. Is this legal ath sanctioned tracks? My cage is welded above the framerails and it's impossible to get a box in there.
Thanks
Dave
 

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I run 2 gauge for the battery and 4 gauge for the alternator. I should probably be running 2 gauge for my alternator because it is a 190 amp but it seems to work OK as it is.

The battery can be bolted to the floor with 3/8" bolts, but J-bolts are not allowed.
 

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I had my battery box install that I did redone by a shop that had really good attention to detail, and I really like what they did. They first bolted the battery box in the trunk area, then welded the nuts both to the underside of the trunk area and inside the box. Instant grounds. The negative battery cable is just connected to one of those nuts with a bolt, and it never leaves the box. Looks super clean, and the mounting points are now fixed.

A bit more work, but if you are interested I can post pics. A bit more work, though.
 

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Thanks for the replies. I think I'm just going to run a 1/8th plate 3" wide between the bolts under the floor for added tearing support if it were to fly up and foreward for some reason during an accident. I just found out that the Monster Wire in 2ga in $3 a foot!!!! I'm headed to the welding shop tomarrow. I'm going to go with the 2 ga for it all.
Thanks guys.
Dave
 

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Dave R said:
Thanks for the replies. I think I'm just going to run a 1/8th plate 3" wide between the bolts under the floor for added tearing support if it were to fly up and foreward for some reason during an accident. I just found out that the Monster Wire in 2ga in $3 a foot!!!! I'm headed to the welding shop tomarrow. I'm going to go with the 2 ga for it all.
Thanks guys.
Dave
You can get 20 ft sections of big 1/O cable from Summit (Taylor kit) for around $50. Not super cheap, but you only need two and you're done, and won't have to worry about charging problems.

TAY-21550 - Red
TAY-21552 - Black
 

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I run 6ga to the starter relay which is on the firewall. From there it is the 1 ga or whatever Hella sells in their cutoff switch kit to the switch inside and then continues on to the battery mounted in the back. The alternator doesn't go to the battery, since the components come off that relay anyway..
 

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jcm3 said:
You can get 20 ft sections of big 1/O cable from Summit (Taylor kit) for around $50. Not super cheap, but you only need two and you're done, and won't have to worry about charging problems.

TAY-21550 - Red
TAY-21552 - Black
Taylor wire is way stiff. Get welding cable, it has a lot more strands making it much more pliable, and I paid about $15 for 25' of 0/1.
 

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5.0Toyota said:
I run 6ga to the starter relay which is on the firewall. From there it is the 1 ga or whatever Hella sells in their cutoff switch kit to the switch inside and then continues on to the battery mounted in the back. The alternator doesn't go to the battery, since the components come off that relay anyway..
The original poster has track times listed in his sig. My guess then is that he wants to be track legal, your method is not.
 

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88POSLX said:
The original poster has track times listed in his sig. My guess then is that he wants to be track legal, your method is not.
it isn't? I figured a short run to where the draw comes from is better than a real long run to the back, maybe I am wrong. If I run the long run to the battery from the alternator it then just comes all right back in the battery cable through the cut off switch to the starter relay anyway right?

I don't race but they don't make rules for nothing so it can't be a bad idea to "do it right."

thx
 

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The way I did mine was to use fender washers on the floor above the gas tank. I believe I only have 2 or 3 of the available holes in the bottom of the summit box actually bolted to the floor on the passenger side. On the drivers side, mine sticks into the spare tire well a few inches so I used some strong angle iron and bolted one side to the bottom of the box and the other side goes toward the passenger side of the spare tire well using some long thick bushings. It isn't welded or anything, but I took my time doing it and I can actually slide the tire well cover under my box to keep the floor area rigid. You could pick my car up from the battery box. It is plenty strong with large fender washers and attention to detail. I had to drop the gas tank to do this but you'd have to for practically any install I believe. Point is, make it solid so if the track officials yank up on the box, the whole car moves and the box don't at all. One of the techs at my track smirked when he tried to pull up on my box and said, "yeah, that's solid".

As for wiring, I put my starter solenoid in the box with the battery, along with a Flaming River cutoff switch. I only used 8 gauge wire running to a mounted stud on the fender in the front. A 4 gauge wire goes from here to the alternator. This is plenty big. Ford only used the equivelant of an 8 gauge wire to connect the alternator to the positive side of the solenoid. I used 8 gauge runnig back to the battery from the mounting stud in front. This is only used to keep the battery charge when the car is running, or run some accessories while the ignition is off. It easily handles my Mark 8 fan and headlights and radio. Those with aftermarket amps drawing a lot of current and fog lights may want to go bigger.
For the relay, you want large wire (preferrebly welding cable 1/0) running to the relay and from the other side to the starter.
This is carrying all the current when trying to start the car. If you go too small, you run the risk of poor performance when the car is hot and the cable is hot. The battery cable may come close to your headers or exhaust system. This will cause the cable to run hot and it will reduce its current carrying capacity. Plus it is about a 12 foot run depending on how you route the wire.
Welding cable is strong and very flexible. It is composed of many fine strands which make it both flexible and excellent for carrying large amounts of current.
**Use large welding cable and you won't every have to do it again**

JCM3 has a good idea with the bolts being welded on both sides and using one as a ground. I ran a 1/0 wire out of my box right to the spare tire well wall and used a couple washers to secure it. I tested the resistance from this point to the front of the car at multiple spots with practically zero resistance, so it makes for an excellent ground. Better than the factory ground even. My car cranks the same in cool weather as it does after multiple starts when it's hot. Proof that large quality cable and a good ground is priceless.
As far as making the system track legal, do a search, there are a few article with wiring diagrams and excellent instructions on how to to a complete job.
The thing that is nice about having the solenoid in the back is that there is a very short run from the positive battery terminal to the relay, and this is contained within the box in my case. This wire is hot all the time, but again, only about 9 inches inside the box with professional grade terminals, crimped and heat shrunk. The positive wire going from the solenoid in the box to the starter is only hot when cranking.

If you want some excellent advice in person, call Mark at MAD Enterprises http://www.madelectrical.com/ and he will tell you everything you ever wanted to know about automotive electrical wiring and battery box installs. He has been feature in 5.0 and Muscle Mustangs and Fast Fords, plus he's as nice a guy as they come.
 

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Discussion Starter #11
The original poster has track times listed in his sig. My guess then is that he wants to be track legal
This is correct. I've been trying to stay within the boundaries of the rulebook to eliminate any doubt in a tech's mind. Plus, they make the rules for our safety so it's only better for me in the long run.
With what you guy's are saying, I just may go with the 1ga if it's that cheap for a 20ft roll. I have a Flaming River switch and Moroso box on order.
Do all the boxes have holes through the bottom of them for the securing rods? Or do they have brackets underneath them for a total seal on the bottom?
I'll have to drop the tank anyways because I'm putting a sumped one or a 1/2" pickup in with a new fuel system so that's not a big deal. Do any of you have pics of your mounting?

Deepstage, I like that idea but my switch(starter) is already relocated in the fender and I will be putting the + wire in flexloom anyways. It'll be routed in the car through grommets and I'm completely confident in my routing abilities. I'd like to have done it that way but I'm happy with this setup.

88poslx, Thanks for the P# and tip.

I would really appreciate any install pics if you all have any. I have a few saved but need a few more variations for comparison.
Thanks guys
Dave
 

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I did mine similiar to the way jcm3 did, but instead of welding, I run washers on both sides of the floorboard and also nuts so the studs can be free-standing. One of mine does go through the framerail also. I pretty much followed Buffhomers diagram for the rest of the install, using 1/o for the pos and ground and 2g for the alt. wire.
 

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I am confused with his wiring, basically the white/black from the D plug goes to the spade clip - and the other two go... go.. where?? nowhere?
 

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Here's a link to a good article on this.

http://www.racesystems.com/3gproj/

I did this a few years ago, but if memory serves me right, you cut the white/black wire from the plug and put that on a new connector (which will plug into the small single terminal on the 3g). I actually just soldered a wire right to the pin and put a connector inline with the wire so I could remove the alternator down the road without un-soldering it.
It is sort of unclear in his article ( I was just speed reading it now), but I believe the yellow and green wire that are on the factor connector (along with the white/black wire) need to be cut free and put on a new connector to fit the 3G alternator. I can't remember if this is a must or if the old plug actually fit in the 3G. If you cut these wires and put them on a new plug, make sure you wire it correctly or you will fry your new alternator. When you put all this together, it becomes amazingly simple. If you are still confused, get back to me, and I will take some pics when I get home from work 5 central time. I will get the exact details if you need them.
 

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the thing is I rewired my alternator when I put the engine in, so what I have is 2 wires to a fusible link to the solenoid. The other wire goes to acc. It is really simple. Everyone refers to this wire going to the factory harness etc etc. All I want to know is where each wire goes :(

There is no lug on the 2g so the other two are hot and give power to the system. Odd the 3g has 3 wires when it SOUNDS (from the article) like you just tape up two and don't use them, then send the 3rd to the stator plug.

Yea, should be easy but I am confused ???
 

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Just read the link, sounds like he is giving power to the stator and ditching the other wires so no plug at all? Why is the plug there then?? Really confused :(
 

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looks like I can run the yellow to the battery connection on the back of the alternator so all I have is a 2 wire alternator - one to the battery and one to a "run" hot. Not too bad..
 

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There is no lug on the 2g so the other two are hot and give power to the system. Odd the 3g has 3 wires when it SOUNDS (from the article) like you just tape up two and don't use them, then send the 3rd to the stator plug.
I am confused with his wiring, basically the white/black from the D plug goes to the spade clip - and the other two go... go.. where?? nowhere?
Just read the link, sounds like he is giving power to the stator and ditching the other wires so no plug at all? Why is the plug there then??
Jeezus, look at the picture I drew! They stay put and go about their business like stock. My diagram is for the stock wiring, made easy. Yours is all different, no wonder you're having fits, don't put it on me. I'd have to go home and trace the other 2 wires off of the D-plug to see where they go and that ain't happenin'.

________________________________________________

You cut the large rectangular plug completely free, leaving 3 wires hanging, 2 ~8ga black/orange-striped wires and 1 ~10ga white/black striped wire (though it could be a different color, don't matter).

Now, the 2 black/orange striped wires each get an eyelet connector and are put on the charging post on the 3G and the nut screwed on.

The white/black-striped (or whatever color yours is, don't matter) get's a female spade connector, and is plugged into the little stator prong thingy on the 3G.

The other plug from your old alternator (the other end of the white/black-striped wire goes to it) simply plugs into the back of the 3G. This plug is shaped like a D when you look at it head on.

1 cut, 2 eyelets, 1 female spade connector. IT GETS NO EASIER!!!
 

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the other two simply go to power, with a fusible link on em.
 

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one of those two you got going to the lug should be run only according to other diagrams but hellifIknow
 
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