RC (Radio Controlled) cars have come a long way since their inception and are now more sophisticated and technologically advanced than ever before. Many enthusiasts are always looking to fine-tune their vehicles for maximum performance on the track. This is to of course remain competitive against others. One of the key components that can greatly affect the performance of an RC car is the droop screw.
In this post, we will explore the function of RC car droop screws, how they work, and why they are important in fine-tuning the suspension setup of an RC car. We will also discuss how to adjust the droop screws to optimize the performance of your RC car on the track.
What are RC Car Droop Screws?
Droop screws are simply fasteners that are installed on the chassis plate of the RC Car and contact the suspension arms. They control the amount of suspension compression when the car is under its own weight. They really are essentially limit screws that restrict the amount of downward travel of the suspension arms.
How do Droop Screws Work?
Droop screws work by simply adjusting them to suit the desired performance required. The fasteners are generally situated on the metal chassis of the car. the body of the screw then comes out the other side of the chassis plate to make contact with the control arms of the RC vehicle. When the screws contact the arms, this is where the limitation in travel is established. One may drive a droop screw further in to limit the amount of downward travel. Or, on the other hand, turning the screw out to provide maximum downward travel.
Benefits of Droop Screws
Restricting Travel
Restricting suspension travel would be more common for RC on road vehicles. This would allow the RC Car to have a stiffer suspension setup when the car is in its natural resting position. Driving the droop screw further in would then further lower the car and stiffen up that initial suspension travel from the natural resting position. Stiffer suspension decreases body roll while cornering, accelerating or braking.
Pros: Stiffer Suspension for on road racing. Lowered appearance or stance.
Cons: minimized grip when the car travels over a bump. Limited Suspension Travel
Un-Restricting Travel
Adjusting the droop screw out so that you get maximum travel, decreases the amount of pre-load on the springs. In this configuration, the natural resting spot in the suspension is not obtained until the RC Car is completely under its own weight. This way the cars weight acts as a force that settles in and matches the force created by the springs in the suspension. As a result, If the car is lifted up slightly, the tires will remain in contact with the ground. This setting is perfect for off-road vehicles and is absolutely critical for rock crawlers where the tire and suspension requires maximum travel.
Pros: Maximum grip when a car travels over a small or large bump in the surface. Maximum Suspension Travel.
Cons: Can not easily lower the car using Droop Screws. Can not pre-load the suspension increasing the amount of spring force when the car is in its natural resting position.
How to Adjust RC Car Droop Screws
To adjust the droop screw, you will need a droop gauge and a droop screw driver. The droop gauge can really be anything that allows you to understand the amount of droop your car has. Consider a ruler for simplicity. There are fancy gadgets and blocks out there, but you really don’t need these. More detail on how a ruler will be used below. The droop screw driver is generally a standard screw driver that is used to turn the screw in or out. This is to increase or decrease the suspension limit.
To adjust the droop screw, follow these steps:
- Measure the Fully Extended Height: Start by measuring the distance between the bottom of the chassis and the ground. This measurement is taken with the car on a level surface and without any weight on the suspension. To do this, the cars weight must be fully supported by something other then its own suspension. Example: use blocks under the chassis plate, positioned at a height to allow the tires to barely touch the ground.
- Measure the droop: Next, grab your trusty measuring device and measure the amount of compression the suspension undergoes when the RC car is now under its own weight. Measure the same specification as in step 1, but the only difference is blocks are not supporting the car, the car is supported under its own weight. Pro Tip – With the car under its own weight push on the car a few times compressing the suspension and allowing the suspension to lift the car back up in to its normal or natural resting position.
- Adjust the droop screw: Based on the measurements taken in steps 1 and 2, adjust the droop screw as needed to achieve the desired amount of droop. Turning the screw in will decrease droop, while turning the screw out will increase the amount of droop.
- Re-measure and Confirm: After adjusting the droop screw, re-measure the ride height of the car vs droop. If the desired amount of droop or the desired ride height has been achieved, you are good to go. If not, continue to adjust the droop screws and re-measure.
It is recommended to make small adjustments at a time. Re-test the car after each adjustment to ensure that you are making progress to your desired result.