Chapter One: Basic Car Maintenance
Perhaps one of the most overlooked
aspects of most novice drivers, and some intermediate drivers for that
matter, is basic care and maintenance of their car. When you are
just driving your car around your local neighborhood, it doesn’t matter
a great deal how straight everything is or if every part is in good condition.
Generally, if the car runs, isn’t loosing parts and doesn’t break, then
there isn’t a problem. However, on the track the difference between
a fast car and a slow car can be measured in 1/100ths of a second.
When it is that close, everything counts!
Most experienced racers have
two or three different procedures for providing general maintenance for
their cars. Between race days, a more thorough inspection of the
car will take place with some of the major components coming off the car
for cleaning and maintenance. If they are getting ready for a major
race, some expert-level racers will tear apart the car completely, even
dismantling the ball bearings themselves for cleaning!
Because between race
maintenance routines vary from driver to driver, we will go over a complete
tear down maintenance inspection. Some pro drivers will do this after
every event they go to (sometimes they’ll do this in between each race day
at major events that take place over 2 or 3 days!) while other casual racers
may only do this once a year. It is suggested that racers do this complete
tear down at least once every 3-4 races during the racing season and more
often if possible. At home before race day, these are the steps that
you should take to make sure your car is ready to go.
Take the wheels and shocks off your car. Inspect the wheels for cracks
and make sure the tires are not coming unglued from the wheel. Replace
wheels and reglue tires if necessary.
Check for and replace any loose or missing hardware such as screws, e-clips,
or set screws.
Set chassis on a flat surface. Use a counter top, glass showcase at the
hobby shop or other flat surface.
Check to make sure the chassis is straight. If one end sits up in
the air or you can see underneath the chassis at some point, it is probably
bent and in need of replacement. Your chassis is the foundation
to your setup and if it isn’t straight, nothing you do to the car will
make a difference.
good set up starts with a good foundation and that foundation is
your chassis. If the chassis is bent, like the one above, the
car will feel inconsistent no matter what set up you put on the
car. The chassis above is bent where the reinforced section
ends (right arrow). Notice that even this slight bend causes
a major difference further down the chassis (left arrow). Remember,
though, that off road chassis usually will have an area on the front
of the chassis that is bent up as part of the design. See the
section on Kick Up further on in this guide.
Remove motor from electric cars. Remove engine, pipe, and header
from gas cars.
Disassemble the front and rear suspension components.
Remove drive train including front and rear differentials, belts, pulleys
and drive shafts.
For Nitro cars, remove electronics from car for cleaning. If
you have an electric car, do this only if the car is so exceptionally
dirty that you may need to use motor spray to clean it.
Remove all ball bearings.
all screws that screw into metal such as aluminum posts or the screws
that thread into the header of a Nitro car. Apply a small amount
of thread lock to the very end of any screw that screws into metal before
all hinge pins to make sure they are straight. Roll them on
the edge of a flat surface and make sure they do not wobble. If
it wobbles, even by 0.5mm, replace them.
the top picture, the slight bend in the hinge pin (marked by the
arrow in both pictures) is almost unnoticeable. However, when
compared to a straight line (or rolled on a flat surface) the bend
is very apparent. Even a slight bend like this can cause serious
binding in your suspension.
all turnbuckles to make sure they are straight. If any are
bent, replace them.
all ball ends and ball cups. If any ball ends are scratched
or out of round, replace it. If any ball cups feel loose when snapped
onto a ball or if they can be pulled off a turnbuckle, replace them.
screws. If any of the heads are stripped, replace the screw
with a new one of the same length and type.
all plastic pieces that have screws threaded into them. If
the screw holes are stripped, replace the plastic piece.
all suspension parts for damage. Suspension components take
a beating and can bend without breaking. If any arms, uprights
or hub carriers show white areas where they have been stretched or if
there is sufficient slop between the suspension arms, hub carriers, or
hubs where the hinge pin slides through (part should rotate around the
pin smoothly but not “wiggle” on it), replace them.
all hinge pins. Clean the holes in the bulkheads and suspension arms that
they run through with a pipe cleaner. Racer Tip: You
can polish your hinge pins with automotive chrome polish to smooth suspension
travel further .
all ball bearings. Ball bearings should roll freely and not
feel “gritty”. Take any damaged bearings, ones that have their
shields or rings dented, and replace them. Clean any bearings
that feel gritty using motor spray and a bearing cleaning tool such as
the RPM Bearing Blaster. Be sure to re-oil the bearings with
high quality oil. Racer Tip: You can
take apart the ball bearings themselves to thoroughly clean them. Note
that disassembling the bearings improperly can damage the bearing. Do
not attempt this if you are unsure.
belts for wear. If the belt is frayed, torn, or ripped, replace
it. If the belt has very rounded teeth or has been skipping
even when the belt tensioner is set to full tension, replace it. Check
the teeth of the belt for debris such as pebbles. Remove and
check for damage, replace if necessary.
belt on the left is very worn when compared to the new belt on the
right. Signs to look for are fraying around the edges (top
right arrow), fraying around teeth (top left arrow) and rounded
teeth (lower arrow).
drive shafts for straightness. Use same method as for hinge
pins. Replace any bent shafts. Check for cracks
or other signs of wear and damage. Replace if needed.
small pulleys for wear. If teeth are missing or chipped badly,
replace. Check for small rocks that may be wedged into the
teeth and remove.
material will become embedded in between the teeth of the pulleys. Using
a toothpick or hobby knife, remove this material from all pulleys.
differentials. If running gear differentials, check to make
sure the differential shafts turn smoothly with no binding. If
there is binding or skipping, disassemble differential and inspect for
damage. Rebuild if necessary. For ball differentials,
check for grittiness. If differentials feel rough, rebuild
for wear in the out drives. If out drives have signs of wear
from engaging the dog bone/universals/CVDs, replace (for ball differentials,
rebuild differential also).
differential pulleys for signs of wear and damage. If teeth
are missing, chipped or worn, replace pulley (for ball differentials,
rebuild differential also). Look for debris such as pebbles stuck
in the pulley. Remove and inspect for damage.
dog bones/universals/CVDs for damage and wear. Replace bent
or broken dog bones. Replace universals that have excessive
play at the universal joint. Rebuild CVDs that have excessive
play at the universal joint and check for tightness on set screw. If
loose, remove and clean set screw then apply thread lock and reassemble.
dog bone shows a common problem in off road racing but something
sedan drivers may see too. The dog bone has been “twisted”
along its axis. This usually happens when an off-road vehicle jumps
and then lands at full throttle, twisting the dogbone. The
ball and pins on the ends of the dog bone should be aligned the
same way on both sides where this one has one end twisted about
90 degrees when compared to the other. This would not warrant
changing the dog bone except for serious racers. However, the
slight bend on the one end of the dog bone (black arrow) would be
reason to replace this dog bone.
axles for wear or damage. Check to see if dog bones are wearing
a notch in axle. Replace if worn. Check to make
sure axle is straight and replace all bent axles.
are two prime examples of when axles should be replaced. The
bottom axle shows signs of wear from the dog bone digging into the
axle under acceleration (black arrow). If not replaced, the
dog bone will get caught in this notch and eventually break the
axle. This is what happened to the axle in at the top of the
picture. This kind of wear can also happen to differential
all linkages for looseness.
Steering Servo Saver for damage and tension.
ball ends for damage. Replace all scratched ball ends.
spur gear for wear or damage. If teeth are missing, chipped
or rounded, replace. Check for debris such as rocks stuck in
the gear. Remove and replace if damaged.
spur gear in the above picture shows definite signs of wear. The
most obvious are the missing teeth (top arrow). This could
cause the car to come to a complete stop even with the engine
or motor revving and would create a noisy drive train. The
other sign are the worn and rounded teeth (left arrow). If
you see teeth like this on your spur gear, replace it as soon
as possible as total failure is soon to come.
the pinion gear (electric cars) or clutch bell (Nitro cars) for wear or
damage. If teeth are missing, rounded, or chipped, replace
gear. Check for debris such as small pebbles stuck in between
the teeth. Remove and replace gear if damaged.
car thoroughly. Use a toothbrush and HPI Nitro Cleaner to clean
stubborn or tough to reach places.
car except for engine/motor, wheels and shocks.
shocks for leaking. If they are leaking, rebuild.
for air bubbles in the shock oil. Refill shock and remove air
bubbles if present.
it has been a while since you have rebuilt the shocks, do so now. Next
to tire selection, shock consistency and performance can influence handling
the most. Get in the habit of rebuilding your shocks often.
shock shafts to make sure they are straight and have no scratches on them. Scratched
or rough shock shafts will cause leakage. Use same method as
with hinge pins, including the chrome polish tip.
outside of shock and spring with a soft cloth.
suspension travel for binding. Lift an axle in the air by hand. Suspension
should move freely and not lift chassis off of the ground until full up
has been reached. Let the suspension fall to the surface.
If the suspension drops slowly, hesitates, or doesn’t fall at all, check
suspension assembly for improper assembly, binding screws, bent hinge
pins or broken and damaged parts.
drive train for smooth operation. If the drive train binds
or skips, check belt tension. If drive train binds in one spot,
check for debris in belts, pulleys, and gearboxes or for bent lay shafts.
Check engine (Nitro cars) for loose, broken or missing screws.
Check case for damage, especially around engine mount areas.
Check for damaged or worn clutch shoes and springs. Replace
Check for damaged or worn flywheel, replace if necessary.
Check glow plug for operation. Replace if burnt out.
Check header for damage and replace if badly bent or cracked.
Check tuned pipe for damage and replace if badly bent. Make
sure pressure fitting and set screw for the pipe holder is in good condition. Replace
if necessary. Check plastic pipes for breaks or cracks. Pay
particular attention to pressure fittings. Replace if needed.
Check coupling between header and pipe for cracks. Replace
Check air filter. Clean or replace if needed.
Check rubber seals around carburetor. Replace if torn or
carburetor is leaking.
Check fuel line for leaks. Replace if necessary.
Check fuel tank. Replace if damaged. Check for
debris in tank and remove. Check primer for leaks (if so
equipped). Remove primer or replace tank if leaking.
Remove motor and disassemble.
Check commutator. Clean with comm sticks if dirty, or have the
motor skimmed or cut if it has not been cut, or is orange, purple or
Check brushes. Clean if dirty, replace if worn, damaged or
if commutator was cut.
Check for play in armature. Shim rebuildable motors if necessary.
Check capacitors for damage and replace if needed.
Check can for debris and small metal parts. Remove.
motor or engine and wheels.
for proper gear mesh.
batteries in transmitter. Recharge or replace when the transmitter’s
low battery warning indicator comes on (usually a light, audible beep
or both). Racer Tip: Never place NiCad or NiMh
batteries in the trash. Take them to your nearest NiCad or
NiMh recycling center!
batteries for receiver (Nitro cars). Replace alkaline batteries
when dead. For receiver packs, check voltage regularly with
a voltmeter or a battery checker like Hitec’s Powermate 2. Anytime
voltage drops below 5 volts, recharge pack. For NiCad packs,
discharge with a high quality battery conditioner such as the FMA Super
Nova charger at .5-1 amp before recharging. For NiMh battery
packs, this conditioning is not necessary. Just recharge the
pack. Racer Tip: Never place NiCad or
NiMh batteries in the trash. Take them to your nearest NiCad
or NiMh recycling center!
for radio operation. Check for glitching or odd radio behavior. Troubleshoot
as necessary. Check and replace/repair broken, cut, or damaged
antennas. Make sure all servos are set as close to neutral
as possible before reattaching linkages. Failure to do so may
shorten the life of your receiver batteries buy up to 50%.
receiver crystal fit. Loose or damaged crystals can cause loss
of control. Replace crystal or receiver if necessary.
and condition battery packs for electric cars. Ten 1157-type
automotive brake light bulbs wired in series can be used to discharge
NiCad battery packs. DO NOT DISCHARGE NiMh PACKS THIS WAY. NiMh
batteries discharge on their own and do not have a memory like NiCad packs. Leave
the batteries in a discharged state until the next race day. Racer
Tip: It is best to use a battery conditioner to discharge and
condition your packs. Also, remember to recycle NiCad and NiMh
battery packs properly.
for proper motor/ESC (electric cars) or engine and carburetor (Nitro cars)
This ensures that
your car is completely clean and trouble free for when you arrive at the
track and allows you to narrow any handling problems to the set up of
the car rather than damaged parts.
Now that you have completely disassembled your car, checked and cleaned
it, and reassembled it you don’t have to worry about maintenance at the
track, right? Wrong. Simply putting your car on the track and
running a single battery pack or tank of gas through it can vibrate screws
loose even if you don’t hit anything or anyone. If you do hit something,
damage to the various parts of your car can occur. Here are some
steps to follow between runs to ensure that your car is still mechanically
Remove wheels from car. Check for cracks in the wheels. Make
sure the tires are not coming unglued from the wheels. Reglue them
if necessary. Clean tires and apply traction additive if you
are using it.
Dust off car with compressed air, paintbrush or both. For gas
cars, you may need to do a more thorough cleaning with a rag or a cleaning
product like Serpent’s cleaning putty. Make sure to get as
much oil and fuel off the car as possible.
Check for any broken or damaged parts. Replace any that you
Remove shocks from car. Check the shocks for leaks. Repair
Set car on flat surface and check to make sure chassis is straight.
Pick up suspension arms to check for binding. Test in the same
method as step 40 above. If any of the suspension arms bind,
disassemble and inspect for damage.
Check all screws for tightness.
Check condition of receiver and transmitter battery packs. If
you are using Rechargeable battery packs in your receiver, do not throw
it on the charger after every run. This is not necessary and may damage
the packs. Only recharge them if their voltage drops below
Clean air filter thoroughly with clean fuel and re-oil with filter oil.
shocks, reattach tires and install fresh batteries or add fuel.
These ten basic steps
will help make sure that your car is ready to go for the next race. This
will allow you to discover a broken part before a race, not during it. If
you ask any professional driver about set up, the first thing he or she
is likely to tell you is that a properly maintained car is the first step
to a good set up. A car with a bent chassis, bent hinge pins, missing
screws or damaged parts will not hold a set up until these things are
fixed. It will be unpredictable and a fast car is a predictable car,
as you will soon see.