What Is End Point Adjustment (EPA)?

End Point Adjustment (EPA, for short) is a function in a RC radio system that controls the maximum amount of travel a servo or throttle channel can move in each direction. It allows you to limit or increase how far the steering servo turns or how much throttle and brake input the ESC or throttle servo receives.

Most modern RC transmitters allow independent adjustment for:
• Left steering
• Right steering
• Throttle
• Brake
• Additional channels on advanced radios

EPA is commonly expressed as a percentage. For example:
• 100% = full default travel
• 80% = reduced travel
• 120% = extended travel beyond default settings (if supported)

In RC cars, EPA is mainly used to:
• Prevent steering bind
• Protect servos
• Fine-tune steering angle
• Adjust throttle feel
• Limit brake strength
• Match radio output to mechanical limitations

Think of EPA as a safety and tuning tool that tells your electronics exactly how far they are allowed to move.

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How Does End Point Adjustment Affect Your Car?

Steering EPA
Steering EPA directly changes how far the front wheels turn.

Increasing Steering EPA
Higher Steering EPA provides:
• More steering angle
• Tighter cornering
• Better low-speed rotation
• Improved maneuverability in technical sections

However, too much Steering EPA can cause:
• Servo binding
• Excessive steering scrub
• Reduced high-speed stability
• Increased servo heat

Reducing Steering EPA
Lower Steering EPA provides:
• Smoother steering response
• Better high-speed stability
• Reduced twitchiness
• Less stress on the steering system

But too little Steering EPA can also result in:
• Poor corner entry
• Wide turning radius
• Reduced steering response
• Difficulty navigating tight tracks

Throttle EPA
Throttle End Point Adjustment controls maximum forward throttle output.

Increasing Throttle EPA
Higher Throttle EPA can provide:
• More acceleration
• Increased top speed
• Faster throttle response

However, excessive throttle EPA may:
• Make the car difficult to control
• Increase wheelspin
• Reduce consistency on loose surfaces
• Overpower low-traction tracks

Reducing Throttle EPA
Lower Throttle EPA provides:
• Smoother acceleration
• Better traction
• Easier control for beginners
• Improved consistency on slippery tracks

This is especially useful for:
• Young drivers
• Indoor racing
• Tight tracks
• Crawlers
• High-power brushless systems

Brake EPA
Brake End Point Adjustment (EPA) changes maximum braking force.

Increasing Brake EPA
More Brake EPA provides:
• Stronger braking force
• Shorter stopping distance
• More aggressive corner entry

However, too much Brake EPA can:
• Lock up tires
• Cause spins
• Upset chassis balance
• Increase drivetrain stress

Reducing Brake EPA
Lower Brake EPA provides:
• Smoother braking
• Better control on low-grip surfaces
• Easier corner entry
• Reduced chance of spinning out

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How Do You Change End Point Adjustment?

The exact process varies depending on the transmitter, but most radios follow a similar setup procedure.

Basic Setup Process
Step 1: Enter the EPA Menu
Navigate to:
• EPA
• End Point
• Travel
• ATV (Adjustable Travel Volume)

Some manufacturers use different names, but the function is similar.

Step 2: Select the Channel
Choose the channel you want to adjust:
• CH1 = Steering
• CH2 = Throttle/Brake
• Additional channels = accessories or extra functions

Step 3: Adjust the Direction
Most radios allow independent adjustment for each direction. Examples:
• Left steering
• Right steering
• Full throttle
• Full brake

Step 4: Increase or Decrease the Value
Turn the steering wheel or pull the trigger fully while adjusting EPA percentages.

Steering Setup Goal
Increase Steering EPA until:
• Maximum steering angle is reached
• The linkage no longer binds
• The servo stops straining

You should never hear the servo buzzing or see suspension parts twisting at full lock.

Throttle Setup Goal
Increase Throttle EPA until:
• Full throttle is achieved
• ESC calibration is correct
• Motor reaches full power smoothly

Brake Setup Goal
Adjust Brake EPA until:
• Maximum braking is strong but controllable
• Tires do not instantly lock
• The chassis remains stable under braking

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When To Change End Point Adjustment

After Installing a New Servo
Different servos have different travel ranges and torque characteristics. EPA should always be checked after installing a new steering or throttle servo.

After Changing Steering Components
Changes to:
• Steering bellcranks
• Servo horns
• Ackermann plates
• Steering knuckles
• Link lengths

…can alter steering geometry and require EPA adjustment.

After Installing a New ESC or Radio
Throttle and brake EPA often need recalibration after changing electronics.

When the Servo Is Binding
If the servo buzzes or strains at full steering lock, steering EPA is likely too high.

When the Car Feels Too Aggressive
Reducing throttle or brake EPA can make powerful RC cars easier to drive.

For Different Track Conditions
High Grip Tracks: lowering Steering EPA may improve stability.

Tight Technical Tracks: more Steering EPA can improve rotation.

Loose Dirt: reduced Throttle EPA may improve traction.

For Beginners
Reducing Throttle EPA is one of the easiest ways to make a powerful RC car more manageable.

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What to Check After Adjusting End Points

After adjusting End Points, inspect the following areas:

Steering Binding
Turn the wheels fully left and right and check for:
• Servo strain
• Linkage binding
• Tire rubbing
• Suspension interference

Servo Temperature
Overdriven servos can become hot quickly. Check temperatures after a run.

ESC Calibration
If Throttle EPA changes significantly, you may need to recalibrate the ESC.

Brake Consistency
Ensure braking remains controllable and does not lock the tires unexpectedly.

Steering Symmetry
Make sure left and right steering throw are balanced.

Uneven EPA values can cause inconsistent handling.

Dual Rate Settings
Dual Rate and EPA can overlap in steering feel. Verify both settings work together properly.

Exponential Settings
Throttle and steering Expo can change how EPA adjustments feel on the track.

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Basic EPA vs Advanced Settings

Basic End Point Adjustment
Basic EPA tuning focuses on preventing damage and achieving safe operation.

Typical beginner adjustments include:
• Limiting steering to avoid binding
• Reducing throttle for easier driving
• Softening brakes for better control

Basic tuning is usually conservative and easy to manage.

Advanced End Point Adjustment
Advanced racers use EPA to fine-tune vehicle behavior for specific track conditions.

Advanced tuning may include:
• Independent left/right steering EPA
• Separate throttle and brake tuning
• Track-specific steering limits
• Brake bias adjustments on dual brake systems
• Fine tuning for traction conditions
• Adjusting EPA to optimize corner entry behavior

Advanced drivers often combine EPA with:
• Dual Rate
• Exponential
• ABS
• Throttle Curves
• Brake Mixing
• Steering Speed

This allows extremely precise vehicle control.

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FAQ

Q: Is End Point Adjustment (EPA) the same as Dual Rate?
A: No. End Point Adjustment EPA limits maximum travel, while Dual Rate changes overall steering sensitivity throughout the steering range.

Q: Can too much EPA damage a servo?
A: Yes. Excessive EPA can cause servo binding, overheating, stripped gears and premature servo failure.

Q: Should left and right steering EPA match?
A: Usually yes, but some racers intentionally run different values to compensate for track layout or steering geometry.

Q: Does EPA affect speed?
A: Throttle EPA can reduce or increase the maximum throttle signal sent to the ESC, which directly affects acceleration and top speed.

Q: What happens if brake EPA is too high?
A: The car may become unstable under braking, lock the tires or spin during corner entry.

Q: Should beginners use reduced throttle EPA?
A: Absolutely, if it’s available on the radio system. Lower throttle EPA makes high-powered RC cars easier and safer to drive.

Q: What is a safe starting point for steering EPA?
A: Most cars start near 90% to 100%, then get adjusted based on steering geometry and servo strain.

Q: Why does my servo buzz at full steering lock?
A: This usually means the Steering EPA is set too high and the servo is trying to move beyond the mechanical steering limit.

Back to the RC Transmitter Settings Guide.