Assuming that all parts are install correctly and the rear-end is square, the information below can serve as good adjustment references. It is good practice to make one adjustment at a time to get positive feedback of the effectiveness. If you make more than one change it can lead to negative/false feedback of whether or not the change made the car's handling better or possibly even worse.
Use a setup sheet or blank paper to keep track as you make changes to the car. If the change is counter productive, change it back to the original setting while making notes as you go. Keep in mind, the track & weather conditions along with inconsistent driving styles can lead to ill handling cars. A driver using consistency throughout the run is very important. Smooth throttle & steering inputs during long practice runs will give good indications of how your setup is working.
- Adjustments should be made one at a time to insure positive feedback
- Front-end changes should be made with the sway bar disconnected
- Reset the sway bar after adjustments are complete
- Actual track testing will improve a driver's learning curve.
Front-end Toe
Toe is the pointing in or pointing out of the front wheels as viewed from the top of the car. If the front wheels point in at the front edge of the wheels then you have toe in. If the front wheels point out at the front edge then you have toe out. This helps in steering stability.
- Typical toe settings for 1/4 scales are between 1/16" to 1/8" out.
- Changing the ride height and camber settings will effect toe.
- Check toe settings after each race if you have contact with another car or the wall.
Pics Provided by Johnson Motorsports
Camber (linked to QSR Camber page)
Trouble Shooting Your Setup
#1. CAR WILL NOT TRACK STRAIGHT (pulls right or left)
(a) Check the toe on the front end or rear of the car.
(b) Something could be binding, not letting the steering return to center.
Examples:
1. Helm end binding up
2. Steering rack binding
3. Servos in a bind
4. Worn out servo savers
If car goes about half way down straight of way and the car starts turning left -
Check RR band. Could be coming loose or host tire could be separating.
#2. CAR HOOKS OFF CORNER (R/R coming around)
Check for the following:
1. Steering could be binding. (Heim or rack)
2. RF host tire is too soft.
3. RF compound is too soft.
4. RF tire has too much camber.
5. RF spring is too weak.
6. RR spring is too stiff
7. RR band is coming loose.
8. RR compound could be too hard.
9. RR tire does not have enough camber.
#3. THE CAR’S LEFT FRONT TIRE PICKS UP (totes LF through the turns)
Check for the following:
1. RF tire compound is too soft.
2. RF or LR spring is too stiff
3. RR spring is too weak.
4. RF or RR tire has too much camber.
#4. PUSHING = THE CAR WILL NOT TURN GOOD IN CORNERS (front tires sliding)
Possible adjustments:
1. RF spring needs less pressure
2. RF tire needs more camber
3. RR spring need to have more pressure or a stiffer spring
4. Rear tires need more stagger
5. RF compound needs to be softer
6. RR compound needs to be harder
#5. PUSH\ LOOSE CONDITIONS = WHEN THE CAR HAS A SLIGHT PUSH
GOING IN THE CORNER AND A SLIGHT PUSH Coming OFF UNDER
ACCELERATION THEN BREAKS LOOSE.
*NOTE* NEED TO MAKE CAR TURN MORE IN CENTER OF CORNER
REFER TO SECTIONS: #4) PUSHING #8) STAGGER #9) TIRE TIP
#6. LOOSE = WHEN YOU CANNOT KEEP BACK END OF CAR FROM (rear-end tries to swap ends)
PASSING THE FRONT END
Possible adjustments:
1. RE tire needs less camber
2. RR tire needs more camber
3. RR spring is too stiff
4. RR shock’s ride height needs to be raised 1/8”
5. RR compound needs to be softer
6. RF compound needs to be suffer
7. RF compound needs to be harder
*NOTE* CHECK AND MAKE SURE RR OR LR IS NOT COMING LOOSE
#7. TIRES - ALL HOSTS MUST BE GLUED TO WHEELS. NO LOOSE EDGES
ON BANDS. *NOTE* NOTHING WORKS IF THIS IS NOT DONE
PREFERRED TIRE COMPOUNDS:
1. RF- 96
2. LF - L-20, L-30
3. LR - L-20, L-30
4. RR - C-5, 405, 410C
#8. STAGGER = DIFFERENCE IN CIRCUMFERENCE OF LR TIRE
(SMALLER) VERSES RR TIRE (BIGGER). THE MORE STAGGER, THE
MORE THE CAR WILL TURN IN THE CENTER OF CORNER. THE CARE
WILL BE LOOSER GOING IN AND COMING OFF THE CORNERS.
#9. TIRE TIPS
(a) If you start off with a car turning or it has a slight push, and after 50 laps
or so it starts getting loose - it’s probably 1 or 2 things.
1. RF compound is getting hot and sticky. It’s biting more which upsets the
Chassis
2. RR compound is getting too hot and giving up. If RR tire grains, you will be
riding on the grain, making the car unstable.
To adjust one or the other, you need to change the compound on tires.
#10. FINE TUNE ADJUSTMENTS
Basically, you want to have even wear across the tire. If the RR wears a little
on the inside, that’s OK. If RF wears a little to the inside or the outside, it’s OK.
TO FINE TUNE A CAR:
1. RR Lower Track Bar needs to be lengthened or shortened.
LENGTHENING WILL TIGHTEN THE CAR UP
SHORTENING WILL MAKE THE CAR LOOSE
2. RF Upper Heim End needs to be lengthened or shortened
LENGTHENING WILL MAKE THE CAR P USH
Shortening WILL MAKE THE CAR TURN MORE
3. RR or LF Shock’s Ride Height needs to be moved up or lowered
MOVING SHOCK’S RIDE HEIGHT UPWARD ON RR OR LF WILL
TIGHTEN THE CAR UP Coming OFF THE CORNERS.
LOWERING SHOCK’S RIDE HEIGHT WILL MAKE THE CAR LOOSER IN AND OFF THE CORNER.
CHASSIS SET-UP
CAMBER = AMOUNT OF TILT IN TIRES
The top of all four tires should be to the left of the car. On a flat surface half of the tire should touch the surface, as a starting point.
TOE IN I TOE OUT = DISTANCE BETWEEN FRONT AND BACK OF
FRONT TIRES AND REAR TIRES
The front of the front tire should be wider that the rear of front tires by 1/16”
toe-in per side. Check this with a long straight edge against the side of the rear tire pointing Straightforward.
RIDE HEIGHT = THE HEIGHT THAT YOU SET THE SUSPENSION
GEOMETRY
FRONT END - With suspension suspended, adjust the shock height to where the
lower control arms are parallel with the bottom of the frame.
NOTE: CHECK SWAY BAR, MAKING SURE IT IS NEUTRAL. (NO PRESSURE ON
REAR ADJUSTING LINKS)
REAR RIDE HEIGHT - Collapse chassis in rear to ground Adjust shock height to
where the shock lacks 1/16” to 1/8” of bottoming out.
SPRING TENSION - AMOUNT OF PRESSURE ON SPRING
LF -20 to 25 lbs. spring with collar sitting on spring top, collapse 1/4” to 3/8”
RF - 12 to 16 lbs. spring, collapse 3/8” to 1/2”
LR - 7 to 8 lbs. spring, collapse 1/2” to 5/8”
RR -22 to 29 lbs. spring, collapse 0 to 1/8”
