I also wonder if the Propshaft UJ angles are in angular tolerance . They can work at different angles , as do LR Discovery 1/2 , but the angles of the propshaft UJ.s need offsetting to compensateThe angle from the vertical of both the gearbox flange and the differential flange must be within 1 degree of each other.
my question is: can the installation angle (the bracket from the lt77 is self-made) be the cause?
I'm shamefully in the same boat, at the same speed. It just seems to be a thing and no-one has fixed it.we have a p6 3500 s that got an lt77. the car has vibrations, from 130 km/h.
.... and tilted the diff by making up spacers etc to get to within one degree of equal....
Ron,
Can almost follow that, BUT, as usual, it does not address the case we have on P6s, and many other vehicles, of UJs installed out of phase by design, and to quote Julius sumner miller " why is it so?". I have searched the web for an explanation to no avail. When I got my car I pulled the prop shaft (forget why)and checked the alignment of the arrows, and corrected the alignment. coincidentally it had a 2000 part no. Over a few 100 kms I had no issues, but on one occasion I had a quite severe vibration, at low speeds, only lasting a km or so. No idea what happened - foreign matter in a wheel?
Ron,
Thanks - T being period of the oscillation ?The change from107d to144d implies a change in vibration with the suffix B diffs?
Why would a stock set up be 5 degrees out of parallel, if it is known that vibration will result ?
"The only answer to me that seems plausible is the out of phase tailshaft design of 144 degrees is there to cancel a vibration that is somewhere else in the drivetrain, the difference between the two being T/2 where T is the period (assuming the waves are sinusoidal, which they would appear to be)."