Driveline vibration

[T.A.P]

I removed the halfshafts & driveshaft today to replace all the unis, upon completion I connected only the driveshaft back to test for any vibrations (the halfshatfs are not connected), so the diff companion flanges just spin by themselves. It was all smooth until about 80kph or 50mph then I can hear the tunnel vibrates, kinda loud. If I rev it pass that speed then its fine, tried gear 3,4 and 5 and all have the same problem.

 

When I install the unis I put both the grease nipples on the same side (the nipples are on the caps) instead of opposite sides, could this be the culprit to the vibration? They are a few grams max, could it be that they caused the vibration since we are talking high rpm here? Ive yet to rotate the driveshaft 180 degree and I'll do it tomorrow, also since they tunnel vibrate without the power transmitted to the ground Im guessing the same thing will happen when the halfshafts are connected?...Please give me some inputs, I dont really want to remove the one uni and rotate the nipple to the other side. Thanks

[Linton]

it wont be the grease nipple, did you have any trouble seating the C clips?? did you rotate or twist the uni after it was fitted ??were they smoothe through both axis??.. you might find it is because the drive line is not under load. my old mechanics training tells me ("scratching old worn out noggin)" it may damage the drive line doing exactly what you are doing.. if all the above were ok just put it back together and road test it.

[620Z]

Well this is the age old question. I have been having this issuue for years and now mine is very minor after changing everything in the drive line. I a, a bit different because I am running a V8. But if everything is done/changed for new like mine. My last option is to strengthen the tunnel where the gear box attach's to it. It's only thin sheet metal taking big loads when under acceleration. So that is just another option to consider. For me my next option will be to maybe cut some chrone molly in half and weld it to the tunnel either side of the gearbox mount for a foot or two.

Won't be the nipple.

Good luck.