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!
 
 

Maintenance Between Racing

1.   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.

2.   Check for and replace any loose or missing hardware such as screws, e-clips, or set screws.

3.   Set chassis on a flat surface. Use a counter top, glass showcase at the hobby shop or other flat surface.

4.   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.
 

A 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.

5.   Remove motor from electric cars.  Remove engine, pipe, and header from gas cars. 

6.   Disassemble the front and rear suspension components. 

7.   Remove drive train including front and rear differentials, belts, pulleys and drive shafts. 

8.   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. 

9.   Remove all ball bearings. 

10. Remove 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 reassembling. 

11. Check 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. 

In 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.

12. Check all turnbuckles to make sure they are straight.  If any are bent, replace them. 

13. Check 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. 

14. Check screws.  If any of the heads are stripped, replace the screw with a new one of the same length and type. 

15. Check all plastic pieces that have screws threaded into them.  If the screw holes are stripped, replace the plastic piece. 

16. Check 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. 

17. Clean 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 .  

18. Check 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.

19. Check 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. 

The 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).

20. Check 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.  

21. Check 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. 

22. Belt material will become embedded in between the teeth of the pulleys.  Using a toothpick or hobby knife, remove this material from all pulleys. 

23. Check 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 differentials. 

24. Check 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). 

25. Check 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. 

26. Check 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.

This 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.

27. Check 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.   

Above 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 out drives.

28. Check all linkages for looseness. 

29. Check Steering Servo Saver for damage and tension. 

30. Check ball ends for damage.  Replace all scratched ball ends. 

31. Check 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. 

32. Check 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. 

33. Clean car thoroughly.  Use a toothbrush and HPI Nitro Cleaner to clean stubborn or tough to reach places. 

34. Reassemble car except for engine/motor, wheels and shocks. 

35. Check shocks for leaking.  If they are leaking, rebuild. 

36. Check for air bubbles in the shock oil.  Refill shock and remove air bubbles if present. 

37. If 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. 

38. Check 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.

39. Clean outside of shock and spring with a soft cloth. 

40. Check 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. 

41. Check 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. 

42. For Nitro cars: 

a.   Clean Engine. 

b.   Check engine (Nitro cars) for loose, broken or missing screws. 

c.   Check case for damage, especially around engine mount areas. 

d.   Check for damaged or worn clutch shoes and springs.  Replace if needed. 

e.   Check for damaged or worn flywheel, replace if necessary. 

f.    Check glow plug for operation.  Replace if burnt out. 

g.   Check header for damage and replace if badly bent or cracked. 

h.   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. 

i.    Check coupling between header and pipe for cracks.  Replace if needed. 

j.    Check air filter.  Clean or replace if needed. 

k.   Check rubber seals around carburetor.  Replace if torn or carburetor is leaking. 

l.    Check fuel line for leaks.  Replace if necessary. 

m.  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. 

43. For electric cars: 

a.   Remove motor and disassemble. 

b.   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 visibly damaged.

c.   Check brushes.  Clean if dirty, replace if worn, damaged or if commutator was cut. 

d.   Check for play in armature.  Shim rebuildable motors if necessary. 

e.   Check capacitors for damage and replace if needed. 

f.    Check can for debris and small metal parts.  Remove. 

44. Reinstall motor or engine and wheels. 

45. Check for proper gear mesh. 

46. Check 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!

47. Check 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! 

48. Check 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%. 

49. Check receiver crystal fit.  Loose or damaged crystals can cause loss of control.  Replace crystal or receiver if necessary.  

50. Cycle 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.   

51. Check for proper motor/ESC (electric cars) or engine and carburetor (Nitro cars) operation. 

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.
 
 

Between Race Maintenance
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 sound.
 

1.   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. 

2.   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. 

3.   Check for any broken or damaged parts.  Replace any that you find. 

4.   Remove shocks from car.  Check the shocks for leaks.  Repair if necessary. 

5.   Set car on flat surface and check to make sure chassis is straight.  

6.   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. 

7.   Check all screws for tightness. 

8.   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 5 volts.  

9.   Clean air filter thoroughly with clean fuel and re-oil with filter oil. 

10. Reconnect 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.