Why Your Clock Runs Fast (And How to Correct It)
A clock running fast is one of the most common and noticeable timekeeping issues. Whether you own a traditional pendulum clock or a smaller balance-wheel clock, gaining several minutes per day usually points to a regulation issue rather than a serious mechanical failure. In this guide, you’ll learn why clocks run fast and how to correct the problem safely—using both pendulum adjustments and balance spring regulator adjustments, depending on the type of clock you have.
Common Reasons a Clock Runs Fast
Most fast-running clocks suffer from one or more of these conditions:
Regulator set too “fast” (pendulum bob too high or balance regulator toward “F”)
Clock is out of beat (for pendulum clocks)
Clock is not level (affects pendulum and escapement action)
Worn or dirty movement (changes how power is delivered)
Balance spring altered or magnetized (balance-wheel clocks)
Temperature and environment changes (especially for pendulum clocks)
Before you start bending, twisting, or taking anything apart, it’s important to identify which type of regulation system your clock uses.
Step 1 — Identify Your Clock’s Regulation System
Pendulum-Regulated Clocks
These include:
Grandfather clocks
Many wall clocks
Mantel clocks with a swinging pendulum
They are regulated by pendulum length and beat alignment.
Balance-Wheel Regulated Clocks
These include:
Some spring-driven mantel or desk clocks
Carriage clocks
Alarm clocks
Smaller mechanical shelf clocks
They use a balance wheel and hairspring (balance spring), usually with a small regulator arm marked “F–S” (Fast–Slow) or “+ / –”.
If you see a visible pendulum ↠ focus on pendulum adjustment.
If you see a small wheel oscillating back and forth with a hairspring ↠ you have a balance wheel clock.
Why Pendulum Clocks Run Fast
For pendulum clocks, the core rule is simple:
Shorter pendulum = faster clock
Longer pendulum = slower clock
The time it takes for a pendulum to complete one full swing is determined primarily by its length. If the pendulum bob is set too high, the clock will gain time. Other factors that can make a pendulum clock run fast include:
Clock is slightly out of beat but still running
Clock is tilted or not level
Temperature changes causing the pendulum rod to contract (colder = faster)
Suspension spring replaced with a slightly shorter or stiffer one
How to Slow Down a Fast Pendulum Clock
1. Lower the Pendulum Bob
Most pendulum clocks are regulated using a rating nut beneath the pendulum bob.
Turn the nut to lower the bob → lengthens the pendulum → slows the clock
Make small adjustments:
Often one full turn equals roughly 30 seconds to 1 minute per day, depending on the clock.
Adjust, let the clock run for 24 hours, and then reassess.
2. Check Beat Alignment
An out-of-beat pendulum clock may:
Run poorly
Drift in time
Stop intermittently
Listen closely to the tick-tock:
Correct: tick…tock…tick…tock (even spacing)
Incorrect: tick…tock……tick…tock (uneven timing)
If the beat is uneven, adjust the crutch or reposition the case until the rhythm is even. A stable beat supports stable timekeeping.
3. Make Sure the Clock Is Level
Use a small bubble level or a leveling app to check:
Side-to-side
Front-to-back
Even a slight tilt can change the way the escapement delivers impulse to the pendulum, causing it to run fast or behave inconsistently.
4. Consider Environment and Age of the Movement
A pendulum clock that hasn’t been cleaned in 5–10 years may have:
Thickened oil
Increased friction
Uneven impulse to the escapement
Sometimes a clock that has started to gain time unpredictably is actually asking for a professional cleaning and overhaul, not more pendulum adjustment.
If you’re near Calhoun, GA, Time and Seasons Clock Repair can clean, lubricate, and regulate your pendulum clock for reliable accuracy.
Why Balance-Wheel Clocks Run Fast
Balance-wheel clocks (similar in principle to mechanical watches) use a balance wheel and a coiled hairspring instead of a long pendulum. The balance swings back and forth, and the hairspring acts as its restoring force.
For these clocks:
Shorter effective balance spring = faster oscillation = faster clock
A balance-wheel clock may run fast due to:
Regulator set too far toward “F” or “+”
Hairspring coils sticking together (often from oil or contamination)
Hairspring slightly bent or distorted
Magnetized hairspring
Dirt or old oil in the balance pivots
Using the Regulator on a Balance-Wheel Clock
Most small mechanical clocks (and many watches) have a regulator arm on the balance cock, marked:
F / S (Fast / Slow), or
+ / –
This arm changes the effective active length of the hairspring by moving regulator pins closer to or farther from the spring’s outer coils.
How to Slow a Fast Balance-Wheel Clock (Minor DIY Regulation)
⚠️ Important: Only perform these steps if you can clearly see the regulator scale and arm. Never pry or bend the hairspring itself.
Locate the Regulator Arm
Look for a tiny lever near the balance wheel with F–S or +/– markings.Move the Regulator Slightly Toward “S” or “–”
Use a very fine, non-magnetic tool (like a wooden toothpick or plastic tool)
Move the arm a very small amount toward “S” or “–”
Even a tiny adjustment can change the rate noticeably.
Test Over 24 Hours
Let the clock run for a full day and note how much time it gains or loses.
Adjust again if necessary, always using small increments.
This method adjusts timing without touching the hairspring coils directly, which is key to avoiding damage.
Environmental and Mechanical Factors Affecting Both Systems
Whether your clock uses a pendulum or balance wheel, the following can push it to run fast:
Temperature changes
Cooler → pendulum contracts → faster
Temperature affecting balance spring elasticity
Vibration and placement
Unstable shelves or mantels alter beat and motion
Old oil and dirt
Friction changes how power is delivered, distorting the rate
If simple regulation won’t hold (you fix it and, within days, it drifts again), that’s a strong indicator your clock needs full service, not just more adjusting.
When to Stop Adjusting and Call a Professional
You should stop DIY adjustments and seek help when:
Pendulum bob is near max up/down and the clock is still fast
Balance regulator is at the extreme “S” or “–” and it still gains time
The clock’s rate varies wildly day-to-day
You suspect hairspring damage, magnetization, or severe wear
The movement hasn’t been serviced in a decade or more
In Calhoun, GA and the surrounding area, Time and Seasons Clock Repair can:
Clean and oil movements
Replace or correctly set suspension springs
Adjust or repair balance springs and regulators
Calibrate timing with proper test equipment
Properly serviced, both pendulum and balance-wheel clocks can maintain excellent accuracy for many years.
