walkerbk Posted February 27, 2020 Share Posted February 27, 2020 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. Quote Link to comment Share on other sites More sharing options...
Neverdone Posted February 27, 2020 Share Posted February 27, 2020 I'd possibly watch out for interfering with the front tire when the suspension is fully loaded, but that's about it. Quote Link to comment Share on other sites More sharing options...
grannyknot Posted February 27, 2020 Share Posted February 27, 2020 Yes you can, some of the s30 racers have done just that. If you go for one of the expensive lithium batteries that are smaller you could go lower than 6". Quote Link to comment Share on other sites More sharing options...
gnosez Posted February 29, 2020 Share Posted February 29, 2020 Not sure how much effect you would get from just moving a battery a few inches lower on braking or handling. 1 Quote Link to comment Share on other sites More sharing options...
walkerbk Posted February 29, 2020 Author Share Posted February 29, 2020 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. Quote Link to comment Share on other sites More sharing options...
calZ Posted February 29, 2020 Share Posted February 29, 2020 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. Quote Link to comment Share on other sites More sharing options...
walkerbk Posted February 29, 2020 Author Share Posted February 29, 2020 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. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 29, 2020 Share Posted February 29, 2020 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. Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted March 1, 2020 Share Posted March 1, 2020 I'm not sure if this is Ron's car, but I found these in an album called "chassis stiffening inspiration". Looks like a similar mod. Album here https://imgur.com/gallery/X86Cl Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 1, 2020 Share Posted March 1, 2020 Don't remember Ron's pic exactly, but that is definitely the same idea. Quote Link to comment Share on other sites More sharing options...
Exposed Posted March 4, 2020 Share Posted March 4, 2020 @ZHoob2004 great source of pictures. Quote Link to comment Share on other sites More sharing options...
walkerbk Posted March 8, 2020 Author Share Posted March 8, 2020 Thats exactly what I am thinking about doing. I can then route my electrical far enough above the battery it wont be an issue or I can pass them behind the fender to clean up the engine bay. Thanks for the photos. Quote Link to comment Share on other sites More sharing options...
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