DIY: Suspension 101: Droop
Measuring & Adjusting Suspension Droop
RC vehicles today have so many potential adjustment points on their suspension that it can sometimes be overwhelming. In Suspension: 101 we aim to explain and demystify the world of RC suspension tuning by breaking it down bit by bit to make it easier to understand.
In this issue, we are going to talk about suspension droop. “Droop” is the term used in RC to describe suspension down-travel and is one of the most crucial settings for suspension performance. Follow along as we break down what droop is, how to adjust it, and what those adjustments mean.
What is Droop and why do we adjust it?
In plain terms, “droop”, or down-travel, is how much the suspension arms will travel below the natural, static ride height of the vehicle. “Natural ride height” just means the ride height of the car measured on a flat surface at rest. When you lift the car up, the suspension arms drop down, thanks to gravity. This drop-down is the suspension droop. Ultimately, droop is physically limited by the shocks, or other suspension travel limiters like droop screws. Droop screws are small setscrews installed in the lower suspension arms to limit travel.
The main reason for adjusting droop is to increase or decrease the car’s grip to match the surface being driven on. Generally speaking, you will want to add droop for low grip surfaces and remove droop for high grip surfaces. Of course, how much you add or remove will depend on your car, the track surface, and other tuning adjustments such as ride height and tires. Just know that droop is a great way to finetune your car’s overall grip and makes the biggest difference in steering and turns.
Before Adjusting Droop
Before adjusting droop there are some key things to keep in mind. First off, make sure shocks are the same lengths on both sides to ensure consistency. Additionally, for on-road touring cars it’s a good idea to check the height from the setting board to the shock ball for extra precision.
Secondly, double check that your springs are the same length. Even if the springs are the same type, extended use and time can eventually make them sag slightly and may potentially throw off your measurements. Lastly, and the most important point to remember is to set your ride height before you make droop adjustments, as changing the ride height can affect droop.
How to Measure and Adjust Droop
Measuring droop can be done in a couple different ways, and ultimately which way you decide on will be personal preference. The first method is to set the chassis of the car on a pit stand with the wheels hanging freely. Take a measurement center-to-center from the top and bottom shock eyelets with some calipers, a precision ruler, or a specialty shock droop gauge.
The second method is to use a flat droop gauge and droop blocks. These two tools go hand-in-hand, so it’s best to use blocks and a gauge from the same company since they’ve been designed to work with one another. Set the droop blocks onto your setting board, place the chassis atop the droop blocks ensuring it’s level, and take measurements at the bottom of the lower suspension arm.
If neither droop blocks or gauges are handy, a third method is to set the car on a flat surface like a tweak board or static pit stand and use a caliper or ruler at the axle, using the centerline of the axle as your measuring point. Subtract the height of your stand from the overall measured length and you’ve got your droop measurement. Just be sure the measure all corners with the same method and you should get fairly consistent result.
Having the proper tools for droop measurement is crucial for consistent adjustments. Ideally you will want a set of droop blocks and a droop gauge, or a precision ride height gauge and a pair of digital calipers. Don’t have anything fancy? No problem, a simple metric ruler goes a long way as well and can be used in place of calipers.
If your car has integrated droop screws, then adjustment can be easily done by turning the droop screw up or down to adjust to the desired droop height. Make small adjustments as a little bit can go a long way. Always make sure to measure twice as you make adjustments until you reach your desired droop.
Your car doesn’t have droop screws? No problem. Not all RC vehicles have droop adjustment screws,
but you can still adjust droop regardless of that being the case. On vehicles like 1/10 off road buggies, it’s a common practice to adjust droop with the position of the bottom shock eyelet.
Adjust droop height by threading the bottom shock eyelet up or down on the shock.
This will either shorten or extend the length of the shock, and effectively remove or add droop to the vehicle. Another popular method of adjusting droop without droop screws is to add spacers inside the shock. Place thin spacers inside the shock below the piston to achieve the amount of droop you desire. This is usually done in small increments with spacers around the shock shaft and is meant to limit droop. Both of these tricks can be applied to almost all types of RC vehicles that lack provisions for adjusting droop on the fly.