Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Replacing hammer knuckles to improve fast repetition action?

I'm buying a 1977 Yamaha C7 grand piano. I'm very happy with the sound of the piano but I expressed a concern to the dealer that the fast repetition action isn't amazing (it's okay, but I've seen better). As the rollers are a bit worn (from Googling, I understand that the rollers are also called hammer knuckles), he suggested replacing them, which would require re-regulating the piano, then doing a very fine regulation of the action over a few days. Does this sound like a reasonable plan? Does replacing the rollers really improve the repetition?

it would, but they are not cheap (better use the original Yamaha knuckles)

as new hammers and shanks is certainly a better option on a piao of that age, you could ask for that or have the replacement envisaged as a project

not only the knuckles (even if they are most important) but also the center pins and bushing, are important for tone control.

after decades the centers can be worn, the cloth of the bushing contaminated by teflon lube or other

new parts mean new centers it is a good advantage too

I would make sure the action is well regulated as is before assessing it for replacement parts. Have you had an independent technician inspect the piano?

BTW I did not understood the dealer proposal, it can be OK?? Just remind the hammers are 35, years old. Yamaha hammers are very dense and can be voiced and shaped for some time, but this is old, it is possible that the nice tone due to recent voicing do not stay put for long.

If your exigence level is not too high that can be OK. Depends of the kind of music you play.
My jazz customers that have old hammers, I need to voice at every tuning and it stay put 6months may be

Greetings,
What BDB said. I have seen many old actions, with worn parts, flat knuckles, and all, that would play as fast as any human can move when they were regulated. Control was another matter, but the speed was there.

You may have a poor regulation, you may have tight jacks or hammer centers, (or both). Unless it is a dream to play, don't buy it without your own person examining it. There are too many other things than the condition of the knuckles that affect repetition speed. How much spring is there, and how much back-check? What is the relationship of the jack to the knuckle, both vertical and fore and aft? Are the keys' sole plates the right thickness?(I transformed a S-400 by changing them to spec). Any balance rail friction? How much aftertouch?

That is just a start.
Regards,

What are "sole plates"?

When the key makers drill the balance rail hole, it is drilled from the bottom of the larger mortise down through the bottom of the key, usually through an added piece of wood at the bottom of the key. This wood is the sole plate. If it is too thick, and the hole is more than 4 mm tall, you will have a sluggish feel to the keyboard. Yamaha's are not immune to this. The way to test is with a tool, dropping the key on the pins won't tell you what is happening. It is just one of a number of things that can slow an action down.
Regards,