Vibration in Rocky F70 Driveline

[dfroog]

I have some issues with a vibration somewhere in the driveline whilst under load, i need to replace the driver side engine mount, but am concerned that this is not the problem, because there is a clunk coming from down there upon take-off as well. Has anyone had similar issues?

[inka]

sounds like a uni to me
replace universal joints per pair per driveshaft

[murcod]

Could be worth trying to grease them if they haven't been done for a while.

[Area54]

Have you done any modifications to the suspension in the last few months, been wheeling hard or dissasembled anything related to the driveline recently?

[dfroog]

The Uni's in the rear are 20 months old, every 6 months they get grease, but i'll try more. I put another transfer and new clutch in 9 months ago but don't think that has any problems. I had some issue's with the tailshaft bolts getting loose, but fixed it, maybe that put stress on the uni's? The front drive shaft is pretty worn, but i don't think that the vibration comes from the front.

[Area54]

More grease will just fling out at rotational speeds - at top speed it will be rotating at faster than engine revs - and the uni bearings don't rotate much if you haven't lifted the car much to create excessive unit angles. Perhaps the slip join is getting a bit loose/worn. Have the two halves of the driveshaft been separated, and perhaps not re-aligned correctly?

Did a shop replace the unis?

The shaft should have the unis in phase at each end - rough diagram:

[dfroog]

Thanks Area54,
I think you hit the problem one the head, i checked the driveshaft, and it was alligned incorrectly. I've re-alligned it and the situation seems to have improved. I'll see how it goes over the next week. A shop did the uni's but i did the tranfers case and and was the last to have the driveshaft off. There's a bit of movement in one of the uni's which has probably resulted from the misallignment for a trip to Adelaide and back (coast road with camper). All seems go though! Thanks heaps

[murcod]

IIRC the Feroza manual says there are paint marks from the factory to show where they should all align- maybe the Rocky is similar and if you clean all the flanges up you might find something??

[Tasrocky]

Wouldn't hurt to make sure you have plenty of lok-tite on the bolts too. They come undone very easliy after ther have been undone once.

[BundyRumandCoke]

Which isnt fun to have happen at speed, about 110km. The whole car shakes like shit.