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My battery tray area is rusted and needs to be replaced. I have removed the old battery tray and started thinking about mounting the battery lower than before.

 

My thought is towards lowering the vehicle center of gravity as the lower, the better braking and suspension will work. Could I cut out the body right below the battery tray and lower the battery mounting location? making a U for the battery to sit in maybe about 6in deeper than the stock location.

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Im working the math on the effects of lowering the 40lb battery 6in should result in around 10ft shorter braking distance due to less longitudinal weight transfer. As for the side to side weight transfer, im not sure but it would for certain be less.

 

I know an alternative would be to replace the battery with a smaller unit and I am for sure going to do so but Im thinking that I will still build the battery compartment for the original size battery.

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19 minutes ago, walkerbk said:

Im working the math on the effects of lowering the 40lb battery 6in should result in around 10ft shorter braking distance due to less longitudinal weight transfer.

Care to share this math? 

 

By itself, I don't think it would make a huge change, but eventually a lot of fractions of inches add up to a foot. Done alone I don't think it makes sense. If you're building the car with a mantra of "get everything as low as possible", then I say go for it. 

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Im actually writing a 30+ page paper on the math right now which means I cant share the paper until i turn it in or it will get flagged for plagiarism but the basis is this:

 

 Longitudinal load transfer = Acceleration (g's) x Weight (lb) x (CG Height (inches) / Wheel base (inches)). this will give the amount of weight that is transferred under certain braking conditions. most drivers can only control a car around -.7 g's.

 

This calculates the load transfer from the rear to the front which then allows for the brake bias to be calculated (the purpose of the paper). Whenever I am done with the paper, i will post the whole math problem but, the lower the center of gravity, the less weight is transferred. 

 

This is not going to be a full track car, just a weekend racer. part of my goal is to lower the CG the other is to just make more room in the engine bay. I dont like how much room is lost.

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I believe Ron Tyler did this on his Z. There used to be pics here, but they're long gone I'm sure. What was done was to set the battery at frame level, cut the (rotten) battery tray and that part of the fenderwell out, then rebuild. The battery is already fairly well positioned in the car fore/aft and offsets some driver weight, but moving it down does have a little benefit. 10 ft reduction in stopping distance sounds optimistic to me, but I'm no engineer.

In addition to moving weight in the car, reducing it also serves the same function. Fenderwells are gone in my car, and I have side pipes, so I had to put it into the cabin. I tried a 3 lb lithium battery, and was going to install behind the driver's seat but then realized that the cabling would add weight, so I stuck it on the trans tunnel. At 3 lb, wasn't so worried about the height of the weight, and it was still lower than the stock position. After I bricked 2 of them, went back to a PC680 and stuck that behind the pass seat and dealt with the extra 15 lbs of battery and cables.

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