"When you leave a floor or level into a floor you get a lot of vibration."
Is this effect happening in both the up, and down directions?
Have you tried speeding up, or slowing down the accel and/or decel, to avoid those slip-stop harmonics?
Is there any isolation between the top of the pistons and the sling, where the pistons bolt up? Maybe you could insert some rubber isolation there.
Do you have an extended crosshead on top of the car, where the pistons bolt up? Sometimes I heard they can flex, might need stiffening.
What did you repack it with? OE? Texacone makes a super slick graphite packing, (well, I think they still do) which reduces friction. Autopack might help, too.
Does the temperature of the oil make a difference? Like, is it worse when it heats up? An oil cooler, (or even a heater! but probably not in your case!) might have some benefit.
Last edited by Vic; 06/25/12 10:41 PM.