HPI's
micro RS4 is ready for fast fun straight from
the box, but if you plan to race your Micro, there's
much you can do to dial it in for track time.
Tuning your Micro to your driving style with maximum
traction will definately shave seconds off of
your lap time. Clear off some room on your workbench
because it's time to start wrenching!
TIRES
HPI, Trinity, Team Orion, Megatech, Dynamite,
GPM and others all offer tires in various compounds
and tread designs; a good thing because tire selection
represents 75 percent of the dialing-in process.
In most cases, you should team softer-compound
tires with the stock, hard-compound tires. This
is especially true if you have a 140mm Micro with
an abundance of steering.
SOFT REARS, HARD FRONTS
This combination will eliminate over steer and
will allow the car to carry more speed through
the corners. If you race with a mod motor and
6 cells, for adequate traction you may need to
install softer tires all around. In most cases,
it's best to run a slightly harder tire in the
front than in the rear.
TIRES FOR CARPET
HPI's 4719 high-performance wide tires are specially
designed for carpet. Teaming these rear tires
with the stock hard front tires is the ticket
for racing on Ozite. Depending on how your car
turns, you may or may not want to “sauce”
the front tires with traction compound. Experiment
by applying traction compound only to the front
tires' inside halves or outside halves.
WHEELBASE & WIDTH
The Micro can be set up with a 140mm or 150mm
wheelbase. The 150mm setup is usually more stable,
and that makes it ideal for high-speed tracks
with wide, sweeping turns. The shorter 140mm setting
is not as stable, but it offers more aggressive
steering; this makes it ideal for tighter, more
technical tracks.
Front and rear width or “track” will
also affect the way a car handles. As a rule,
a wide track with a short wheelbase (a “square”
footprint) has more steering and less rear bite;
a more rectangular footprint (narrow track with
a long wheelbase) has more rear bite
REAR SHOCK TIPS
The same principles apply to the rear shock: if
you want to increase steering by taking away rear
traction use a thicker lube on the rear shock;
if you need more rear bite, use a thinner lube.
A little lube on the shock shafts is all it takes.
SHOCK SPRINGS
HPI, Team Orion, Megatech, GPM and several other
RC sources offer color-coded tuning spring sets
for the Micro. Orion's spring set includes red
springs (stiffer than the stock, black springs),
and blue springs (softer than stock). HPI's set
includes “medium firm” green springs
and “firm” blue springs, both of which
are stiffer than the stock HPI black springs.
STIFFER
SPRINGS
Stiffer springs usually require more damping to
prevent the suspension from rebounding harshly.
Stiffer springs also reduce grip; use them for
higher-bite conditions.
SOFTER SPRINGS
Softer springs require less damping; if you over-damp
a soft spring, the suspension action will become
slow and mushy. Soft springs yield more grip;
use them when traction is low.
REAR DIFFERENTIAL
The Micro's rear gear diff does a decent job,
but a ball differential will operate more smoothly
and can be adjusted for looser or firmer action
(never set the diff so loosely that it slips).
HPI, Dynamite, Megatech and others offer ball
diffs that work very well.
LOOSER REAR DIFFERENTIAL SETTING
A loose setting increases rear traction when cornering,
but it may also cause the diff to “unload”
more easily on high-traction surfaces that cause
the car to unweight its inside tires in tight
turns.
TIGHTER REAR DIFFERENTIAL SETTING
The car will have less rear traction when cornering
because more force will be required to activate
the diff. If traction isn't sufficient to activate
the diff while cornering, the inside wheel will
have less traction as the diff tries to turn it
as quickly as the outside rear wheel.
FRONT DIFFERENTIAL
The Micro's front gear can be tuned by installing
a stiffer or softer spring between the brass planetary
gears. HPI's tuned spring set includes soft and
firm diff springs.
SOFTER FRONT DIFFERENTIAL SPRING
Installing a softer spring allows the front diff
to rotate more freely and will enhance steering.
STIFFER FRONT DIFFERENTIAL SPRING
A stiffer spring will slow diff action and reduce
front steering.
FRONT ONE-WAY DIFFERENTIAL
If you really want to free up your drive train
and improve your car's high-speed steering, try
installing a front one-way diff. The front one-way
provides full power to all four wheels during
acceleration, but allows the front wheels to freewheel
during coasting and braking. A one-way also gives
a car more high-speed steering, but it will have
rear-wheel braking only. If your transmitter has
endpoint adjustments, use that feature to adjust
the brake throw so full brake power falls just
short of locking the rear tires. When using a
one-way, HPI suggests an upgrade to steel or aluminum
universal axles, as a one-way setup puts a greater
strain on the axles.