Springtime! Upright Action Spring Servicing

Upright Action Spring Servicing

Why Some Old Uprights Feel Amazing

Have you ever played a century-old upright and thought, “Wow, this touch is incredible”? Light, responsive, almost delicate—it’s like the piano is reading your mind. Then you sit down at a modern upright, maybe even a Yamaha, and something just feels... off.

Often, that magical feel in older uprights comes down to spring tension. Most players don’t realize it, but we technicians know—springs matter.

 

The Three Main Springs in Upright Pianos

Jack Springs – These help reset the jack after escapement.

Damper Lever Springs – Control the return of the damper felt to the string.

Hammer Return Springs – Assist the hammer in resetting after a strike.

Each of these interacts with the others in a delicate choreography. Adjusting one can alter the entire feel of the action. On older uprights, you may also find a separate spring rail that holds hammer return springs, unlike the integrated systems in newer designs.

 

Adjusting Springs in the Field

• Using a Hart Spring Tool or even tweezers, you can:
• Soften the touch by reducing spring tension.
• Add resistance by increasing tension.
• Reposition or re-engage springs that have slipped out.
• Replace broken or missing springs using tacky glue, rubber cement, or standard PVC.

Pro tip: There’s no universal weight spec for these springs—it’s all about feel. Some techs use Yamaha uprights as a baseline because of their consistency.

 

The Role of the Spoon and the Symptom of Touch

It’s easy to confuse spring tension with damper timing. While springs control force and return, spoons control timing—when the damper lifts in the key stroke. This also affects feel, but in a different way. Sometimes, adjusting the spoon earlier in the stroke makes the touch feel heavier. Later? It might feel lighter or more expressive. Understanding both is key to achieving what your client wants.

 

When Springs Fail

Sometimes you’ll find a jack spring missing or broken (sheared flush inside its channel). In these cases:

• Reinsert or replace the spring.
• Stretch or reshape damaged springs.
• Use tacky glue to keep new springs secure but flexible.

Other Touch Factors: Friction and Verdegris

Before adjusting springs, always rule out friction. Sticky pins or warped felts can mimic spring issues. Another hidden issue? “Verdigris”—a Steinway-era chemical treatment that turns into sticky black sludge over time. If you encounter it, repinning might fix it—but only for a few years. Supply88 is currently testing a new product called “Vertigon” to treat it long-term.

 

Bonus Tips

Noisy spring rails? Add a dab of grease to eliminate creaking in Yamaha uprights.

Hammer return springs? Rarely adjusted unless you’re working on an antique.

*Every piano tells a story, and it’s our job to help it sing. Springs are one of the hidden tools in our technician’s belt to fine-tune that story into something truly playable, beautiful, and responsive.