BATTERIES ON THE MOVE
BATTERY TRUNK RELOCATION
Battery trunk relocation
Classic muscle cars are decidedly heavier in the front than in the rear. That should come as no surprise to anyone who has tried to autocross his or her American reardrive vehicles. With the engine and all the heavy stuff up front, a muscle car can often have as much as 65 percent of the weight on the front axle. Not only is that not good for cornering, but it’s also not great for rear tire grip when under forward acceleration.
So as we review the underhood features of our muscle car, the question becomes: What can we relocate under here that would make a difference to the weight bias of our car? Unfortunately, the answer is not much, with the exception of that 50-plus pound black box we call a battery. In testing, it has been proven that moving a battery from underhood to the trunk can change weight balance 1 to 2 percent. That’s a huge improvement.
Lead acid batteries can weigh over 70 pounds, and as we’ve seen with some pure race factory offering like lightweight 1968 Dodge Hemi Darts or a 1963 Max Wedge B-body, the factory not only moved the battery to the rear, but installed a super heavyweight battery to help with traction. That’s not a bad idea, especially when you consider that a battery in the trunk with high cranking amps is important to overcome the increased length of the battery cables that’ll be required to activate the starter five times the length of the factory cabling.
Our 1974 Plymouth Duster was a good candidate for a battery-in-trunk modification. With the car stripped to the bare floors, it made it easy for us to demonstrate just how it’s done. In addition, we added a kill switch that’d be mounted under the driver seat to allow us to turn off all electrical elements of the vehicle — and provide an anti-theft system that would make the Duster that much harder to steal.
The parts shown here were pulled together from a variety of sources, but kits for battery relocation can be found from a variety of vendors like Summit Racing and Classic Industries. For our application, we purchased the master lock-out switch and the battery cabling from an automotive supply store, and the battery
tray from Eddie Motorsports. The Optima Yellow Top 34/78 battery was something we just had on hand. Note that this battery features 750 cold cranking amps and 120 minutes of reserve capacity, making it perfect for our Southern California–based Plymouth.
Follow along as we send our battery to the trunk. This is a very simple modification that can be completed in about an hour if you have all of the components. You’ll need simple tools and a hole saw to cut through the sheetmetal to allow the cabling to pass through from the front of the vehicle to the rear. Charged up and ready to go?
Here’s how it’s done.
Moving the battery to the trunk on our 1974 Plymouth Duster could make a 1 to 2 percent difference in the vehicle weight bias front to rear. With more weight in the rear, handling in corners is improved as well as weight transfer under hard acceleration.
With the wire covering stripped off enough to fit into the eyelet, we crimped the eyelet in place with this crimper. We used this steel hammer to apply enough force to the crimping device.
We selected #1 gauge wire to handle the power transfer from our soon-to-be rearmounted battery to the engine components and negative ground point.