This article was published with special permission from RC Car Action.
DROOP SUSPENSION
This truck doesn't have typical coil springs. It runs a droop setup
with internal springs.
SUSPENSION SYSTEMS HAVE SPRINGS, RIGHT? Well, not always, or at least
not in the way you are used to seeing. Springs are easy to spot, so when a
vehicle sits with none of the expected coils at each corner, it tends to
stick out. In rock crawling, a rig like this is mostly likely set up with
what is called a droop suspension. To further complicate matters, even
though you can't see any, most droop suspension setups do have springs. Keep
reading and find out what droop is all about.
The name droop comes from the fact that the vehicle isn't
suspended by traditional external springs and is instead allowed to
rest with shocks fully compressed. In fact, most often internal
springs are used to help keep the shocks compressed (just the
opposite of what springs usually do). People often wonder how this
type of system works. Since rock crawlers use solid axles, the axles
pivot as the crawler passes over obstacles. One shock is forced to
expand, and then as the truck moves forward and over the obstacle,
it compresses under the force of the internal spring.
Because of its droop suspension, the center
skidplate sits low on TCS's Edge tuber.
The main advantage of a droop suspension is a much lower center
of gravity. A crawler with droop simply sits lower. A
traditionally suspended rig with approximately the same amount
of suspension travel will sit higher and thus have a higher
center of gravity; and center of gravity is one of, if not the
most important setup characteristics of a crawler. Another
benefit is that a properly set up droop suspension will extend
as the center section or skid-plate comes in contact with the
ground.
SETTING UP DROOP
Droop provides a potentially great advantage, but only if
it's properly set up. And droop can often be harder to dial in
than a traditional suspension. A poorly dialed-in droop
suspension will cause problems that far outweigh the benefits.
It's important to realize that there is no single magic droop
setup. What works for one crawler will not necessarily work on
another. Many variables such as vehicle weight, your driving
style and terrain all impact which setup is needed. Three common
setup options for droop are: springs, damping and travel.
SPRINGS. The correct spring for your vehicle will be
strong enough to keep the uphill shocks from expanding when
side-hilling (thus preventing in a roll-over) and yet soft
enough to allow the shocks to extend when the center of the
truck comes in contact with the ground. The weight of your
crawler will play the biggest factor in determining the right
spring.
