RC10Talk - The Net's Largest Vintage R/C Community

I've never been an actual racer but I know I've read of your car could only be so light. Is this still the case and have the weights come down over the years? Was wondering why have a minimum limit at all? Just thinking as technology advances and as those super capacitor technology gets better the batteries will weigh almost nothing. Are the racers going to have to keep adding weight as the batteries get smaller but stronger?

I think for any given size of car, going below a certain weight would actually negatively impact performance. Without sufficient downforce and a thorough understanding of airflow, a car that's too light will not get enough traction on acceleration or turning and will launch & fly unpredictably off of jumps.

for 2wd off road it was 3lb 4 oz and i made my wieght easly back in the day .. not sure now

Coelacanth wrote:I think for any given size of car, going below a certain weight would actually negatively impact performance. Without sufficient downforce and a thorough understanding of airflow, a car that's too light will not get enough traction on acceleration or turning and will launch & fly unpredictably off of jumps.

I agree. I think we are already pushing that limit with today's cars. Seems like it is already fairly common for racers to add weight to a car.

As for actual rules, I don't know specifically what they currently are for roar, rc pro, etc., but for club racing I don't think anyone is going to weigh your car.

When a car that jumps becomes too light, another form of vehicle becomes more logical: the airplane.

The lighter it is the faster the car can go, and in the old days the lighter the car the longer it would run with the limited battery capacity. take a load of weight off and you could gear up for more speed.
Minimum weight limits mean you didn't have to use expensive exotic materials to reduce weight. 20 years ago when we ran converted buggies as wide touring cars, with no minimum weight limit you would be paying a three figure sum for a titanium motor mount. With a reasonable weight limit you don't have to use expensive parts to get down to it and it keeps the racing fairer. Weight limits tend to get changed as technology changes, when touring car modified went to 5 cells the chassis weight was reduced to get the speed back up to the 6 cells we were running before. When it went to lipo the weight limits were increased to compensate for the extra voltage.

On road if you can run light you will be faster. Less weight means faster cornering speeds, less tyre wear, less battery power used which gives you a higher average voltage which gives you more straight line speed as well. Touring cars tend to add a small amount of weight but that is to balance the chassis not to add weight just for the sake of extra weight, they use the minimum necessary. It's not so much of a problem in off road, buggy racers tend to add extra weight to help balance the chassis and stabilise it over bumps as todays motors and batteries means the chassis are way overpowered compared with on road.

All the minimum weights can be found in the various rule books, each organisation sets their own weight limits.
Over here in the UK the minimum weights are 2wd buggy 1474 grams, 4wd buggy 1588 grams, touring car 1350 grams and 1/12th 730 grams

As the capacity of lipos is going up they are packing more density into the limited size the the packs, so they are getting heavier, not lighter these days.

Soon enough the batteries will change again. Those are evolving at a very fast pace compared to say the electric motor. I guess that will just leave more tuning for the driver if they have a couple of ounces to move around.

Thats the only good thing about being under weight, is that you can add weights where you want it. I've never been a fan of adding chassis weight, I always wonder why people time and time again stick on huge stacks of weights. If it wheelies turn the punch down, if it doesn't turn move the battery forward.

It's like people tune with weights rather than tune the chassis.

Thats the only good thing about being under weight, is that you can add weights where you want it.

If your car is a runner at less than minimum weight, you can add ballast where it helps performance. Much preferable to all the mass being where it has to be to function, with only as much regard for balance as the design will permit.