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I'm planning on spending some money (probably too much) on mods to improve the handling of my car.
I feel that our cars (SS) can easily do with some better weight distribution ie: move front to back.

My preliminary conclusion is that a battery relocate to the trunk sounds like a very cost effective way to improve weight distribution.

Has anyone done it? Results?
How to?

I'd like to stay away from the "why don't you get a lightweight battery" please. In my case this isn't possible because I live in the north and I need all the bat power I can get when it's -40. Also, as I said this mod seems to be a good one if all it cost is some brackets in the trunk and a 15ft piece of 4 gauge wire.

To the people that say "get a lightweight battery" I say "Id much rather spend 250$ on some whiteline goodies" If I had a LW battery I'd still consider putting it in the trunk.

i haven't done it yet, but, i was also contemplating moving the battery to the trunk. LMK how it works if you do it.

Wow!! really nice write up

http://wgbuckley.com/projects/battery.html

PS: another side benefit is more room in the engine bay for ..... well I'm not sure yet, but with an FMIC and VF 39 in store, I'm sure it will come in handy.

I update the thread for sure when I decide to do it, and again once it's done.

I moved mine to trunk when I did the initial motor swap and fmic plumbing. iwanted to put it on the passenger sid ein the trunk, but with the multi-tray, thats really not possible. I welded angle brakets to the trunk so I could hook on to something with a racket strap.

I used three 4 gauge grounds in the trunk. Two were on posts that I welded to the trunk floor right above the main frame rail of the structure that runs along the driver side. For the other ground I found a nice spot behind the trim in that corner.

I already had a very nice 4 gauge amplifier power wire running up front that I used for my power. I would like a larger wire for my main power because when its cold and I try to start with my heater fan running, a few things don't like it so much.

I added four extra 4 gauge grounds from the motor to the chassis, which may be overkill, but you can never have too many grounds. Since I removed the factory air box I had plenty of places to bolt to.

93forestpearl wrote: i wanted to put it on the passenger side in the trunk, but with the multi-tray, thats really not possible. I welded angle brakets to the trunk so I could hook on to something with a racket strap.

I plan on putting mine on the pasenger side as well, what do you mean by this?

93forestpearl wrote: I used three 4 gauge grounds in the trunk.

Is one ground not enough? I understand the advantage of well grounding the batery in the engine bay, but will this make a difference in the trunk?

93forestpearl wrote: I already had a very nice 4 gauge amplifier power wire running up front that I used for my power. I would like a larger wire for my main power because when its cold and I try to start with my heater fan running, a few things don't like it so much.

Really!! 4 gauge not enough, so you'd go to 2??!! that's huge.

I dont' know about in the US, but for all the canadians out there, you can get the Optima red top battery @ Club Price for 159.99$ (219.99 at Napa plus the dick wanted to charge me some bogus 10$ shipping) Picked mine up a couple of days ago, starting to put stuff together for the instal.

Have you weighed how much the added cables, brackets, and whatever else will be? You will be adding weight to the car no matter how small. Plus you're talking about maybe a 1% move in weight distribution, with no real testing that it is a good move anyway. More rearward weight isn't always the best move. You would be better off removing weight from the car in an equal fashion. Plus you could get better results from the car with numerous different things, tires being the first things that come to mind.

Canadian Turbo wrote:I dont' know about in the US, but for all the canadians out there, you can get the Optima red top battery @ Club Price for 159.99$ (219.99 at Napa plus the dick wanted to charge me some bogus 10$ shipping) Picked mine up a couple of days ago, starting to put stuff together for the instal.

napa is such a rip off.

I would want more weight in the front though. When you take off there is more force in the rear.

SemperGuard wrote:Have you weighed how much the added cables, brackets, and whatever else will be? You will be adding weight to the car no matter how small. Plus you're talking about maybe a 1% move in weight distribution, with no real testing that it is a good move anyway. More rearward weight isn't always the best move. You would be better off removing weight from the car in an equal fashion. Plus you could get better results from the car with numerous different things, tires being the first things that come to mind.

Well I've put 6000$ in mods on the car at this point so tires are done as well as many others. Weight has been removed wherever possible (AC, air bag/control unit, sunroof, even a custom carbon hood on it's way) the rear seats will go when winter rallying starts again next fall.

From experience I believe that it is a good move in terms of weight distribution. This winter on a particularly slipery day at the track I had a bunch of stuff in the boot (maybe 60lbs) and the car had better acceleration and seemed to drift more predictably. Could be wrong tho, I'm not a pro, nor do I have any fancy graphs to prove any difference, just the butt-o-meter.

As far as brackets and whatnot, no I haven't checked on the weight. However seems to me like 20ft of 4 gauge wire can't be THAT heavy plus it'd be evenly distributed, and what a fuse? Id make the tie downs out of alluminum since I don't weld and it would be easy to grind and drill most of the stuff out of alu. Plus the steel tie down from under the hood can go.

Trust the butt.... for it is wise.

I relocated my battery to the trunk...mostly just to free up space in the engine compartment.

I ran 1 gauge +12v cable, and a 1 gauge ground to the body, as well as a 4 gauge ground back up to the motor (the reason for that is a long story)...It seems to work great...although I didn't really notice any differences in the way the car handles.

My battery is in the trunk too.

I needed room for FMIC tubing so the battery had to go into the trunk.

I used a battery relocation kit from summit racing that included everything needed to put the battery in the trunk (I put it on the drivers side as it was easy & the battery was on the d/s stock anyway).

The weight distribution of these cars is front biased so moving 1% of the weight to the rear should help get you closer to a 50/50 F/R weight split.
That said I did not notice any major difference in the handling of the car after relocating the battery.

Sorry for not replying sooner. I kinda spaced it out on remembering this thread.


I used all those grounds for redundancy. I didn't want to rely on one ground for everything. I have a friend who fried his Hydra, injectors and a bunch of suff in his STi due to a lame ground on his trounk mounted battery.

I shouldn't have assumed my 4awg wire isn't enough. I need to buy or make a nice distribution block in the engine bay for my wires. Right now I have a distribution "bolt" where my wires all have ring terminals around a big bolt, cranked down very tightly. I've insulated the hell out of it so it can't short anywere.


As far as where you can put a battery and box in the trunk, IIRC there is really only room on the drivers side, if you want to be on the main floor of the trunk. You could remove hte multi-tray, build a bracket and what no to put it anywhere if you wanted to. My car is a daily driver and I wanted to keep the multi-tray.