With today’s cars we’re often finding that once assembled with your favorite electronics, favorite hop up parts, and in the case of the stock classes your favorite drivetrain reduction parts, your car is under minimum weight. In mod classes, we often use weight to change how the car responds to inputs as well as jumping characteristics. So let’s take a look and a few reasons why you’d add weight, and where you may put that weight.
In stock racing you ideally want your car just over the minimum weight. The reason, while obvious to most of you is to give you the lightest car for your motor to push around the track saving heat, power, and efficiency. A lighter car simply gives less of a load for the motor to work on. So once you build your stock class slayer and you weigh it up and find out its 70g under minimum weight, what do you do?
There are a few options. One I do first is to run the car the way it sits, underweight. Determine if the car could use some weight to adjust its handling. Does it need more on power steering? IF it does I know I can add 7 or 14g of weight to the front area of the car either near the front bulkhead or near the steering servo to add weight over the front tires giving you more steering. What if the car is a little erratic when jumping? Adding some weight to the centerline of the car near the battery can help numb the car while not affecting the handling of the car as much if you were to add the weight to one end or another.
If your car needs more forward bite, you can add weight around the rear axle area. This can be done by going to aluminum rear hubs, aluminum or brass rear toe blocks, or even adding rear weight designed for the car that bolt to the rear of the car such as the TLR brass waterfall weight. Ideally you want to keep the weight near the center of the car as to not induce some laziness in the left to right transitions. Weight added towards the wheels will slow suspension action down, which in itself is yet another tuning option. You’ve been seeing these “hub weights” on 1/8 cars lately.
If the car handles really well underweight then you simply need to add weight in areas that will continue to keep the cars natural “balance” on each of the 4 corners. Corner scales are the easiest way to do this but since I’m old school I use a MIP Tweak Station. If you built your kits shocks to be equal length left to right, you can use the spring collars depth length on the shocks to get you pretty close.
Don’t forget that the fitment of you electronics will have a big effect on the left to right as well as fore and aft weight. Take your time laying out your electronics on the bench to assure equal weight on the two sides of the car. Often times you will find a few ¼ ounce weights are needed on the receiver side of the car simply because they’ve gotten so small land light over the years(see above picture).
Weight is an often overlooked tuning tool by most. It can be a great choice when you’re 95% happy with the car but just need a little nervousness out or just a tick of steering in “that one section” or just could use a little more grip out of the apexes.