vibration

[flexy trol]

hello everyone, I have a 98 diesel flat tray patrol which seems to get a vibration in fouth and fifth between 75-85 and 95-110 both at the same revs aswell 2600 in fourth and the same in fifth. And if you take your foot of the accelerater but you are still going the same speed the noise will go away, the clutch was replaced recently too im not sure if that could cause anything. the vehicle has 10inch lift with a modified 5link front and the gearbox has been lowered. its been lifted like this for 14 months and the problem has only just begun. please send me your thoughts on this problem, thanks

[Area54]

Lowered the gearbox, (I'm guessing to match up the drive flanges - parallel) you didn't mention if you also had adjustable upper control arms, to help here. Sounds like something from the driveshaft area. Reason for it showing up just now? something (like the unis) has just worn out to the point that vibes appear. Any wheeling damage visible on the shaft - dents scrapes etc?

[big red]

how much is the spring lift?
could be unis or the slip joint or you have the hubs locked in as the front shaft tends to vibrate at any more than around 6" lift

[A1]

Off topic but how bout some pics sounds huuuuuggge

[totto]

Strange, i've got the exact same symptoms on my standard height lwb patrol with td and 5-speed. Not vibrations in the car, but vibration sounds at exactly the same rev, regardless of gear position, but only under load, not under engine braking or idling.
In addition i've tried to test it out with the box in neutral with the car both standing still and rolling. The sound is gone when reving the engine without load.
Just a flying idea, but could this be the bearing of the input shaft on the gearbox? That's the first and only part i can think of that always follow the engine revs with clutch engaged regardless of vehicle speed.

[flexy trol]

some pics

[bogged]

the vehicle has 10inch lift

Why?

[flexy trol]

because I dont go much on body lifts, and besides this used to be leaf in the front, so the flatter chassis made it easy to lift because the coil tower didn't sit as high as one does on a normal coil cab so I still only had to use a 6 inch coil and the control arms are adjustable.

[DR Frankenstine]

sounds like one of you're rear shocks may have fallen off again. hehe Not racing 4 wheel motor bikes down southport beach again hey sam. So is gavs taller than yours yet. He seems pretty convinced height=off road abillity (wrong). Has he got any suspension flex yet?