Sounds like the tolerances of the piston to packing may be on the tight side. You could try adding some Cat oil to lubricate the piston and packing. Cat additive is available at most heavy equipment suppliers. Tensioning is done the same as any traction elevator. Is this a new job, or has it always vibrated? Are these pistons single stage or multistage? Any air in the jacks? Does it vibrate in high speed? How quickly is it transioning to level speed? Is level speed high enough? Does it vibrate on inspection? From the getgo, and after inspection for a distance? Does it ever smooth out?

isnt there an equalising copper tube between rams? i wonder if your pressure between rams is slightly different. i would suggest adding this oil additive to test as its the easiest to do firstly.i would increase your speeds to test also. as stupid as it sounds have you lubed your rails? seen it plenty of times!!

X2 on cat juice.

X3 on Cat Juice and Cat juice only we had a job went thru the same problems and were adding another brand. Finally used Cat jucice all fine now.

Cat works for 2 days. It only vibrates on the left piston. Pistons are single stage. I will cheak the air. No vibration at high speed. It does vibrate on insp. It does get smoother toward the bottom of the hoistway. The job is six years old installed by mitsu.... We changed the packing its the right size. Butcher has 1 ring yellow packing w/ a black nylon ring on the inside of the ring, weird. I am kinda thinking building compression, and movement, jacks ar'nt plumb?

I don't know if you have,but check the plumbness of the jacks,and check on the number of 90 degree connections leading up to it.
Just a suggestion.

I would think one of your jacks are not plumb.

Easy way to check it is to run the car up to the top and drop a plumb bob down.

Has this job had this problem from day one? If the jacks are plumb, you might try the polishing tool from Texacone to try to get the tolerance between the piston and seal to be a little more forgiving. Have you put a micrometer on the pistons to see if there is a difference between the two pistons? You could swap heads on the twocylindersto see if there is any anomaly in the outer bore bunching the seal.

probly stupid question but have you checked your rail centres.if the vibration gets better the lower you go i wonder if either your car centres or the left ram rails have moved. you may be able to test this theory by loosening your ram guides(assuming slippers). with lots of clearance then the ram will centre itself and hopefully not vibrate. do this on inspection.

Another thing to check is to put a straight edge from top of jack head to top of jack head and check for level. (A water level will work too). Its possible your vader could be wracked due to jacks not being level with each other. Just throwing out an idea.

We will only use Texacone supream green packings do to similar problems

So here is the update. The answer is cable tension, squaring the cab w/ the guides, and packing tightness. It runs perfect now. Thanks for the help....