In setting up a car for handling it's preferable to attempt to attain a 50/50 weight distribution so that all of the wheels share the load of getting a car around a corner as equally as possible. For drag racing, one strives to get as much weight as possible over the drive wheels to help traction. A car's heaviest end is often the opposite of what is ideal, such as a front-engine rear-drive car or a front-wheel drive car.
To try to improve the weight distribution, race car builders have resorted to things like setting the engine back to get more weight where it can do good. This is fine for the serious racer but out of the question for the average enthusiast. But what if you found out about a mod where you could get the same change in weight distribution as setting the engine back 5-10 inches that took very little time and money to do? You'd probably jump all over this, right?
You can get all of the benefits of setting the engine back by simply relocating the battery from the front of the engine compartment to the trunk. This simple mod can change the weight distribution of a car from 1 to 2 percent. This is a big difference that can easily be felt by the driver in terms of less understeer and/ or better traction.
To show the remarkable effects of a simple battery relocation project, with the assistance of Steve Mitchell of M-Works we took a driftmodified AE86 Corolla and put it on corner scales with 200 pounds of weight to simulate a driver in the passenger seat. We moved the battery around the inside cabin to showcase the differences in weight distribution by simply altering the battery mounting position.
Corner scales are electronic scales used to set up the chassis of a race car with adjustable coilovers. The spring heights of each corner are adjusted to get a 50 percent crossweight percentage with the driver's weight in the seat. When the crossweight percentage is 50 percent the car will have an equal balance in left and right turns, regardless of the driver's offset weight in the car. The more balanced the better the weight distribution.
Here is how our experimental stock Hachiroku weighed at each corner.
| ||Left Weight ||Right Weight ||Battery Location ||Front-to-Rear Weight Percentage ||Crossweight Percentage |
|Front Weight ||725 ||642 ||Stock left front of engine compartment ||54/46 ||49.4% |
|Rear Weight ||606 ||552 || || || |
As you can see there is quite a bit of difference between the left and right weight of the car. The crossweight isn't bad considering that the car hasn't been corner balanced.
Now we moved the battery to the right side of the trunk.
| ||Left Weight ||Right Weight ||Battery Location ||Front-to-Rear Weight Percentage ||Crossweight |
|Front Weight ||668 ||646 ||Right rear of trunk ||52/48 ||50.8% |
|Rear Weight ||638 ||575 || || || |
Now you can see that the weight from the right side of the car to the left side is much more equal. Best of all, the front-to-rear weight percentage has improved by 2 percent, which puts the car pretty close to the ideal 50/50 weight distribution. This has the same effect as setting the engine back around 10 inches. A 2 percent difference in weight distribution is easy for a driver to feel.
Next, we moved the battery to the left side of the trunk to see what would happen.