acclaim wagon vibration issue

[fillbee]

hi, i have a low klm wagon purchased with 46K and now has 70k on the clock
having been to about 4 mechanics now and nobody can find the vibration issue
a vibration starts at 50kph and runs to about 60kph , feel from the back as its not thru the steering. I also find I cannot comfortably cruise above 90kph as it produces a drone in the cabin (my son describes it as being in a airplane)
there is also a Dook Dook noise from the rear that is intermittent , often comes in when off throttle (like down hill)
I have replaced tyres
Have tail shaft balance checked (ok) and in process replaced centre bearing

any clues?

 

[Trevor loves holden.]

Might be your torque converter, might be the diff.

 

[rambunctious]

Sounds very much like a problem I had you are describing a harmonic vibration often caused by engine and or gearbox mounts being too harsh.
Have these been replaced at any time ?

Replace with genuine mounts from holden, not repco, not superthief, not anyone else, must be holden.

The dook dook from the rear could be cyclic knock in the diff.

Do a search on cyclic knock and here is just one post about it
https://forums.justcommodores.com.au/threads/diff-noise-cyclic-knock-a-holden-service-issues.73713/

 

[fillbee]

Sounds very much like a problem I had you are describing a harmonic vibration often caused by engine and or gearbox mounts being too harsh.
Have these been replaced at any time ?

Replace with genuine mounts from holden, not repco, not superthief, not anyone else, must be holden.

The dook dook from the rear could be cyclic knock in the diff.

Do a search on cyclic knock and here is just one post about it
https://forums.justcommodores.com.au/threads/diff-noise-cyclic-knock-a-holden-service-issues.73713/

Thats the only positive info I v had in what's cost me over a grand thus far
blessings to ye

 

[fillbee]

Sounds very much like a problem I had you are describing a harmonic vibration often caused by engine and or gearbox mounts being too harsh.
Have these been replaced at any time ?

Replace with genuine mounts from holden, not repco, not superthief, not anyone else, must be holden.

The dook dook from the rear could be cyclic knock in the diff.

Do a search on cyclic knock and here is just one post about it
https://forums.justcommodores.com.au/threads/diff-noise-cyclic-knock-a-holden-service-issues.73713/

My mechanic thought it was wheel bearings, so he stripped it down in preparation to replace, then decided bearings were fine.
after reassembly I was unable to detect the noise for about a week. then it slowly returned.
A while back he changed the diff oil and commented that it was unusually dirty for such low klm
All indicates that this could be the problem
thanks again

 

[Fu Manchu]

What about going to the wreckers and grabbing a new tail/drive shaft?
For what it will cost, a cheap way to eliminate a possible cause for less than paying someone to do it.