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Discussion Starter · #1 ·
i have a jegs kit that i bought for my 89 lx trunk. i plan on putting it on the passenger side in the trunk. where are the best places to run the positive cable up front and where is the best place to mount the negative cable. also will i need to dropthe gas tank to drill the holes for the studs. any good ideas and addvice would be great.
 

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Discussion Starter · #2 ·
bump.
 

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Do a search on this. There is about a billion threads on it. Lot's of people run them inside, lot's say they like 'em on the outside. I prefer in thru the interior.
Yeh, you gotta at least get the drivers side strap loose, drop the pass side strap, & the filler neck. Neg cable to a quad-shock bolt works well. Ground, up front, frame to blk. Migt want two grounds up front. Go to Buffhomers site for wiring. Don't go smaller than 1 gauge for pos. & neg. cables. 2 gauge alt wire.
Mega fuse for the pos. cable. Nice t use a 130 amp alt also. Use a kill-switch too.
 

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I just mounted my battery in the trunk of my 93 coupe. You only have to drop the tank a few inches to get you hands to the base of the trunk floorpan, just make sure the bolts don't stick too far down. I ran the positive wire over the rear pass. rearwell, under the backseat to the drivers side, under the carpet, then inside the drivers fenderwell to the stock positive cable mount point. I rean the negative wire from the battery to the pass rear quad shock mount, then mounted the stock negative wire to the drivers sway bar mount. I have run this setup on my 94 Cobra for 5yrs with no problems.
 

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Take your time when installing the bolts above the tank. You'll run into areas where you can't access from below. Measure a lot and make sure you save room for a roll bar if you plan on one.
Here is a pic of mine. It's an aluminum box from summit. Not sealed, but very easy to mount. What I did was drill 2 holes in floor above gas tank. I used good grade 8 bolts. Put a fender washer on the bolt and run it up from the bottom so bolt head is in gas tank area. Put another fender washer on top then a good locking nut. It won't stick up very high. Plus you may need it to stick up a little higher than floorpan level here just so the whole box sits level. What you have done is install a stud. You will never have to mess with this again. You can easily remove the box without having to access the area below the floorplan. The holes in my summit box were large enough to fit over the bolts (3/8" I believe - have to be a minimum of 3/8" for NHRA rules), but small enough where the bottom of the box can rest on top of the nuts without adding a washer for a seat. The other side is a little more tricky. If you put it toward the middle far enough, you may need to fabricate something for that side to attach to. It takes some time, but when done right it will be very solid. I used a piece of angle aluminum attached to the side of the spare tire well. I had to measure a lot and makes some custom tapered bushings to countour to the side of the spare tire well. Another method is to run some solid steel channel across the back of the spare tire well. You can then T another piece of channel from the back to the wherever it needs to line up with the left side of the battery box.
As for wiring. I ran a 1/0 welding cable through my car and out through the passenger side floor pan only a foot or two away from the starter. I used a heavy duty grommet to protect the wire. I rarely have passengers so I'm not too worried about their feet beating up the wire, but I don't think it would ever be a problem anyway. It's a pain cutting a hole in the floor there but it worked out nicely. Just remember, large quality wire is a must here. It needs to carry a lot of current at least 12 feet to the starter. I grounded mine right on the spare tire well, at the front bottom. It is somewhat close to the fuel pump for reference. The pan is thing here, but with the surface area involved, there is plenty of contact for a ground. Mine works absolutely great. There is no resistance to current flow from here to any part of the engine bay up front. It makes for a cleaner install to ground the battery there too. Only a very short piece of wire needed. Spare tire has plenty of room still too.
My solenoid and cuttoff switch are both mounted in my battery box. Makes for a very clean installation. If you need more info on any specifics, let me know. I will take some pics if you need to get an idea.

 

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Discussion Starter · #6 ·
will do gonna start on it monday.
 

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I had help from my neighbor when I did mine and he said that I shou;dn't run the cable thru the car for heat reasons. If you did get the wire hot or a short, you could burn up your interior. He's an old school drag racer and has seen it happen. He recommended going out of the trunk as soon as possible with the leads. It takes some time mounting the positive under the car, but it turned out good and now I don't have to worry about my brand new interior going up in smoke. MY car isn't a drag car, so I guess everyone has a differing opinon. My 89 is a trunk car also, and I put it right in the spare tire well. I used a Taylor box, with 1 Gauge wire and it turned out pretty sweet. Good luck and if you want a pic or 2 let me know. [email protected]
 

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Properly fused, you shouldn't have any worries about heat build up. The only danger is really the charging cable from the alternator, but properly fused you should be fine. You wouldn't be in any more danger than any other fox body with the crappy headlight switch acting as the power source for the lights.

As far as the cranking wire. If you mount the solenoid in the trunk with the battery, the wire is only live while cranking the car. I use a good 1/0 welding cable. It would take a hell of a lot of cranking to heat that thing up.
I think a good install is running the wires through the subframe connectors if you have they type with a big enough opening. Great if you run the wire outside the car.
 

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Discussion Starter · #9 ·
if i run it under the car what do i use to hold it up with and where is a good place to run it at.?
 

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I ran mine up against the subframe connectors and used some zip ties (steel), or you can use some hangars to do it. I used 1/o welding cable, which is specifically made to withstand the elements.

Deepstage is right, there is absolutely no danger of running it inside the car as long as you have it fused and heat is no problem with a large enough wire. It's no different than having a bunch of live wiring for the rear lighting at night, it all runs underneath the carpet. Just be sure and use grommets on the areas where it passes through a bodypanel and make sure nothing can rub or pinch the wiring.

http://buffhomer.corral.net/custom.html
 

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I did my setup a long time ago when a bunch of us were talking about it on the corral. We chose 150A marine type fuse you can see in this pic.

My question is what is the right size fuse?
Because my tuner f'ed up putting the alternator nut back on and melted that end of the wire as you can see in the "Bad alternator wiring (not by me, but fixed by me)" folder here http://www.roemedia.com/test/gallery_engine.php

I cant put the link strait to it because it has the f-word in the title ;D
 

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Discussion Starter · #12 ·
i plan to keep the solenid in the engine compartment. this car isn't gonna be raced. so i see no need for a on off switch. also is there a need fir it to be fused.? this is a weekend street car.
 

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Would high quality 2 gauge wire be enough to run from a rear mounted solenoid to the starter? I called PA Perfomance (they are a great company to deal with, by the way), they suggested a 2 gauge wire from a 130 amp alt, to be on the safe side. If that is on the safe side for the alternator, wouldn't it be more than sufficient for a starter? I know they draw a lot of current, but it's for a relatively short period of time. I'm gearing up to do this install but, there is a huge price difference between the 1/0 and 2 gauge wire, like $1.50 a foot.
 

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The stock starter cable is 4ga, so yep, 2ga will work great.
 

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buffhomer,
thanks for the reply, and the very informative website.
 

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I just mounted one in my 89 coupe this weekend so here is the skinny on what i did.
First make sure that you put the box in a place that will cause no binding or interfere with any of the trunk latches or rods, and remember that you will also have a battery cable coming out of the box that needs room to run around the trunk without any binding by the trunk hinge.
Assuming you have a coupe and not a hatchback, run you positive cable across the trunk and yo uwill see a rubber gromett close to the driver's side shot tower. This hole goes through the trunk and straight through the frame. I ran mine all the way through and let it sit on the frame. I use some insulated wire straps i found at home depot in the electrical section and they worked great! There is a coulple of places you can use tie wraps to secure the positive cable but i used about five wire straps. Two in the back to make sure it wouldnt bind with any of the suspension parts and two under the floorpan area. Then one where it runs close to the exhaust to make sure that it didnt have a chance of coming in contact with my h-pipe. Hope this helps, let me know if you have any questions about the rest of the installation.

Piece,
 

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A couple of things. It does not matter how long the starter is drawing the current for. The fact that it draws a lot of current is the reason you need a larger gauge wire. Also, you are talking at least twice the distance to run from the solenoid in the rear to the starter as opposed to the solenoid mounted in the factory location. Longer distances require a larger gauge wire due to resistance in the wire itself. Why are you worried about the cost of good quality 1/0 welding cable. Get 20 ft of it. It will be enough for your ground and starter cable. At $1.50 you'll have a whopping $30 invested. That couple with a few extra bucks to purchase the properly sized termianls is still peanuts. You don't want to do all this and find out your wire is undersized. It may do fine now, but what about the future? Put a higher compression motor in that is harder to start and you need a little more help. Wire close to the header will reduce the wires capability to carry current to some extent also.
Cost should not be an issue. Do it right the first time, or skimp and regret it.
I installed 1/0 welding cable from the start to rear mounted solenoid. I grounded the battery at the bottom front of the spare tire well (it's thin material, but makes for a great ground). I also have dual engine grounds up front. I'm using 2 4gauge wires for those. I have absolutely no starting problems or current flow problems. You may not need 1/0 gauge, but why not be rest assured you have plenty to handle any job.
If you are planning on making your install NHRA acceptable, you better do some serious reading and understand how the various switches, wires, alternator, battery, etc, etc, all interact and make for a properly designed system. If you don't know the difference between the current flow of a starter and that of the alternator with the mere load of the ignition and several accessories, I'm assuming you don't have the knowledge to properly install a rear mounted battery. If you are not worried about NHRA legality, that is one thing, jury rig it and cross your fingers. If you are doing an NHRA legal install, call [email protected] MADelectrical.com and tell him your plans. He will take the time to give you all the info you need. Beware however, it involves running a few accessories off of relays and isolating them from the alternator. If the alternator is not isolated, your car will stay running even when the safety switch is flipped. If it is not isolated properly, then you risk damaging your alternator, ignition system, computer, etc when the tech officials shut your power off to make sure it kills power to the whole vehicle.

Don't take anything I said as a flame, I just hate seeing so many people install rear mounted batteries and not finish the job correctly. It's not easy, but the benefits will be great if you do it correctly. Mark can also explain to you the benefits of running different accessories off of relays instead of Fords method of routing the current for headlights, foglights, etc, through the wimpy switches. There's an easy fix for flickering headlights, assuming you have upraged your alternator previously.

Need any specific info for your application, pm me, I'd be glad to discuss it.

Paul:D
 

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Cool stuff thx Paul. Years ago I put a relay right behind the hlight switch, but ran the existing wire (brown/yellow I think) to the hlights with a new large gauge + wire to the relay. It worked, but now I'm not too much of a monkey so I'll setup the factory switch as it used to be and use a new relay closer to the hlights and power in the front of the car. That way I dont have to run so many wires through the firewall. Sounds good?
 

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Discussion Starter · #20 ·
i decided to put my battery in the spare tire compartment. and to run a cutoff switch. and hide it behind my license plate with the flip down cover. i am going to use a 150amp in line fuse very similiar to what buffhomer did. where is the best place to mount the fuse. i was thinking about inside the trunk. my kit came with 2 guage posite wire. i am going to stick with it. anything else i should look for.
 
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