K021 Instructions v1.0
Tuning
Page
81
Limiting uptravel (adding spacers outside the shock body) is rarely used, usually only in
the rear to prevent the CVD bone from bottoming out in the outdrive.
Finally, we discuss shock mounting. Changing the bottom shock mounts affects quite a
lot: the further inside the shock is mounted on the arm the softer the suspension feels
(because the wheel has longer lever arm on the shock) and the more travel you have.
To keep downtravel the same, it’s generally recommended to add .060” (1.5mm) of
spacers inside the shock for every hole you move in on the arm (and take out spacers
when you move out, obviously). Running the front shock on the inside hole will add low
speed steering at the expense of stability. The more in the rear shock is mounted, the
“safer” the truck will feel around the track: it’s softer and soaks up bumps better.
Moving the rear shocks out on the arm will add steering and is generally recommended
for high traction, smoother tracks.
The upper shock mounts are much easier: the shocktower’s holes are designed in an
arc so that the suspension travel doesn’t change as much. Inclined shocks (mounted in
on the tower) have a progressive feel to them. They’re smoother around the track and
provide more side bite. Vertical shocks have more forward bite and are better over
jumps.
CHASSIS FLEX
All materials have some give to them, what we in R/C commonly refer to as flex. Most
often racers pay attention to how much and where their main chassis plate flexes, as
this can have a subtle but important effect on the truck’s overall handling.
Pure bench-racing theory suggests that having zero flex is ideal: by making all the
components as rigid as possible, everything the truck does will be strictly controlled by
the tires, shocks, and suspension geometry (all the things we’ve discussed so far). This
is desirable because all those things above are easily measured and deliberately set.
However, when the rubber hits the dirt, racing experience has shown that some chassis
flex can be a powerful tuning tool, and setting and controlling the right amount of flex
leads to a faster truck overall.
You can tune the flex in your SCX-60CF by loosening or removing some of the screws
in the top deck. For more rear traction on bumpy, loose, or slick surfaces, you can
remove the two rear-most screws in the top deck and/or the motor plate’s T-shaped
brace. To allow more torsion flex (allowing the chassis to twist), you can remove the
two outer screws from the middle three posts. Both of these changes will take away a
bit steering and make it more forgiving, which is great on blown-out “gas-style” tracks.