Outer Limits 4x4 Board

Now before everyone says bushes, wheel alignments etc my vibration is not associted with these they've all been checked and new bushes and rubbers put it. vibration isnt in the steering, steering wheel or front end, its coming through the floor from the middle towards the rear and rattling my sphincter something fierce.
its running a 3" lift, extended rear lowers , 33's, gu diffs with 4.3's, adjustable panhards, adj draglink and hd tierod.

symptoms:
had the rear wheels in the air on a trolley jack and in drive, could hear a grinding/loud bearing noise from what sounded like the transfer case
under really hard acceleration i can just feel a vibration through the floor
starts vibrating at 80klm very slightly by 90 its getting pretty dam rough at 100 im making scrambled eggs on my dash.
the vibration feels to be at the speed of the driveshaft spinning, not the tyres (high frequency vibration not a big thumo thumo thumo vibration)
if cruising at 100klm the vibration is present but when i get into it from there it instantly gets worse
doesnt mater what gear im in it always starts at about 80klm
only does it when in rwd or 4wd, with driveshaft out and in fwd it doesnt do it at all.
have been told by previous owner that "had a speedy sleeve put on the pinion shaft because the seal track was rooted"
rear diff doesnt make and whining or noises out of the norm

so far:
replaced driveshaft and put new uni's into it (this didnt fix it, made it marginally better by maybe 5-10%)
have had the transfer pulled apart and the output shaft bearing for the front and rear changed to new items and this made it better again by maybe 10-20%
rear wheel bearings were apparently changed by a professional according to previous owner

Has anyone had a problem similar to this???? The mechanic thats doing the transfer case at the moment has called and said that he cant get one of the gears out of the transfer case and his next move he wants to do is pull the gearbox and transfer case out so he can get at it easier, is it necessary to pull the box out to remove transfer??

cheers
bally

diff bearings ?
The transfer comes off the gearbox seperately no problem, I have had a couple off.

Just to be clear did you get a new tail shaft or just replace the uni's in the old shaft if new shaft check pinion bearing and back lash on diff

another driveshaft with new unis in it just to be sure, not the original one with new unis

make sure both driveshafts have the yokes lined up..ie...both fixed yokes have to be lined up or parallel with each other. they can misaligned if the slip joint has been pulled apart...and also check the balance of shaft. Another issue is the angle of the shafts with a 3 inch lift could be too acute with the gearbox needing spacers fitted on rear mount

HTH.


Cheers Keith

problems been fixed, we dunno what we did but putting it all back together and now it doesnt vibrate........

ST391GQ wrote:make sure both driveshafts have the yokes lined up..ie...both fixed yokes have to be lined up or parallel with each other. they can misaligned if the slip joint has been pulled apart...and also check the balance of shaft. Another issue is the angle of the shafts with a 3 inch lift could be too acute with the gearbox needing spacers fitted on rear mount

HTH.


Cheers Keith

That's what i would have mentioned, tail shaft unis out of phase.

Maybe the mech fixed it on the quiet when he realized what he'd done.....