[CAUT] buzzing truck

Alan Crane alan.crane at wichita.edu
Thu May 15 13:32:14 MDT 2008


At 10:02 AM 5/15/2008, Dennis Johnson wrote:
>The truck on our #2 performance piano has a problem buzz...


I would block up all three arms, under the legs, and 
loosen/re-tighten all the "stop sign" bolts and the arm adjustment 
bolts too (with or without PVCE or other additives) and see if that 
didn't solve the problem first.

I block arms up with two layers of 2x4 glued up (see photo), though I 
generally put the block squarely under the leg and let the bolt/nut 
just sink into the wood if I'm going to be yanking on the truck 
assembly for adjustment or other purposes.

( sorry for the large photo file... I don't know how to reduce it )

With blocks securely under the arms like that, you can even 
disassemble the entire "stop sign" assemby if need be.
I use this procedure to install trucks under grands, assembling them 
first and installing under one leg at a time, then making final 
adjustments & tightening with all arms blocked up and no load on the 
arm/stop sign assembly (its easy to get the leg ferrules dead-center 
in the arm "cups" at the same time).

For truck assembly/installation, I usually use the Jansen & Son 
"jack-in-the-box" but for work on trucks already in service I've 
often done all the lifting using a lever & fulcrum made from 2x4 stock.

Let us all know what you end up doing to solve this problem.



Regards,

Alan B. Crane,  RPT
School of Music
Wichita State University
alan.crane at wichita.edu 
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