uni joint question

[Glennb]

Hi all, Just wondering how loose should my uni joints on the rear tail shaft should be. I took it off today to check them and I have found that the transfercase end uni joint is a little looser than the rear one. The rear one is a little firmish to move but does still feel smooth to move.They both have been pumped full of grease.
Could this small tightness in the rear uni cause a vibe through my drive line? or would a bearing have to fully collapse?
Cheers
Glenn

[want33s]

IMHO ANY play in a uni joint is too much. I would replace a uni if i could feel/see movement in it.

[Glennb]

sorry probably wrong choice of words beingLOOSE. Their is no movment were there shouldnt be , but the bearings feel just a little tighter than the front uni .

[rhymus]

Has the uni been changed recently? Whether it has or hasn't doesnt make much difference, just give the yoke ears a whack with a hammer to free them up a bit. You may find this loosens them up a bit. Just be careful not to hit the yokes where the bearing caps are pressed into the shaft but up a bit where the ears are welded to the shaft. In all the joints I've replaced this is th emain trick to getting a smooth uni.

[want33s]

AHHHH OK.... Rhymus has hit it on the head. A tap on each of the 'ears' with a brass hammer is standard practise when fitting new unis, to make them centralise and free up the movement.

[J Top]

In my experience the 3.0 rear shaft is soft and easily damaged when replacing uj's. The "ears" can be misaligned giving binding in the uj and even an out of true, elliptical, rotation.

[Glennb]

Thanks guys, I took my tail shaft and a new uni to a tail shaft specialist and he took one look and feel of it then said they were ok. I explained that the rear felt a bit tighter than the front and he then turned around and basicly did what rhymus said to do whacked it.
So I took the new uni back to Mitsu and got a refund. I have given up on this vibe as I have taken it to 8-9 different mechanics literally , Mitsu had it for the day and also could not find the problem so I will just have to wait till something goes bang. Hopefully not while Im up in the high country.
I have done:
New control arm bushes (did nothing)
fully greased and checked uni joints (all ok)
had a tail shaft balance ( all ok)
bought new stock springs put them in ( vibe went by 40% but still there)
Vibe has been there with 2 different transfer cases
vibe is there with 2 different sets of wheels
Vibe is worse when riding the brake or exalerating but also feel it when slowing down but not as bad.
vibe comes and goes through speed not rev range (worse at 40ks)
Have narrowed it down to drive line, transfercase to end of tail shaft. But what is actualy causing it ,no one knows.
Cheers Guys anyway
Glenn

[want33s]

Have you checked the pinion bearing ? Have you lifted car? Is there enough tailshaft yolk in the box ?

[Glennb]

Have not checked the pinion bearing in the diff, but has been to 2 diff places and they have said it would be highly unlikely to be the diff.
Its only got a 40mm lift in the rear so there plenty in the box. The vibe is there at stock height and slightly worse when raised.
When I put it into 4wd the vibe goes slightly but feels like it transfers it to the front of the car as I can feel a little vibe through the steering wheel when in 4wd. This tells me that the case is jumping around for some reason but what causing it is the mystery. uni ok, yolk ok, balance ok etc..
Just going to have to live with it for one more year I think, then bye bye.

[paulv1818]

Have you checked/changed the oil in the transfer/gear box? after refilling the box in my old scorpion it had a horrible vibe - i had overfilled it.