VIBRATION at highway speeds, need help

[sssadamsss]

I have a 97 TJ with rebuilt axles.

brand new front AND rear drive shafts. i have the rear driveshaft yoke angle at the diff end set to 2 degrees down, and the front shaft yoke at the diff end set to 0 degrees, all in relation to the shaft.

I have new bearings all round, and new tires. i have a 4" long arm kit.

So all is well at below 70kph. but as soon as i get above, i start getting an oscilating vibration that comes and goes over a 2 second cycle. so it will gradually get worse, then gradually go away. 2 seconds to get worse and two seconds to go away. its driving me nuts! it gets worse the faster i go...

i cant feel any play in any of the shafts...
Ive ordered a new tranny mount, but underneath it all looks good, so i doubt its going to be the issue.

Any ideas guys??

[sssadamsss]

bump bump

[4WD4FUN]

Have you tried a process of elimination ,
Try dropping front drive shaft off and driving without it and try Hubs engaged then Hubs disengaged If you have freewheeling Hubs to see if its the axles.
If it’s gone you know it’s the front end drive shaft if in good condition then it might be out balance or is your spline one tooth out the one photo looks a little out but this could be an optical illusion.
If no change re install and drop rear drive shaft and drive on front only and see if this makes a difference you will not get wind up as there is no drive to back wheels without drive shaft.
Do you have the vibration at speed when you push the clutch in and coast at this speed or place in to neutral with foot off clutch.
You may need to try a few things But have had drive shafts out of balance do this.
Hope this helps

[Tassie Jeeper]

i have the same issue over 100km but its constant and the faster i go the worse it gets i have new uni's front and rear and have the vibes before getting them and still have them

[sssadamsss]

Thanks for the help guys. after what 4wd4fun wrote, i went out under the car and tried to see if the flanges were out of alignemnt. its hard to tell in the dark, but i thikn they may be. Tomorrow morning im going to pull the rear shaft out and see if i can look straight down at it. and ill try driving on the front...

[sssadamsss]

Well Guys, have a look at these pics... looks like its on the piss to me!!!!

[sssadamsss]

So i went for a drive in front wheel drive, no rear shaft, no vibrations at all.

I then put my old slightly worn driveshaft back in (not the new one) and i got the exact same vibes as i did with the new one??????

Im pretty sure its not the rear pinion angle, ive tried about 15 different angles. ranging from 5 degrees down to 2 degrees up (in relation to the shaft)...

what does that mean? Something in the rear Axle????