Hello all,
I have a rather elusive vibration issue on a 1991 RR (3.9 EFI) with a LT77 gearbox and the infamous BorgWarner transfer case. It is not felt through the steering.
It happens at 80km/hr(50 mph) in 5th gear, but not in 4th. Accelerating in 4th to 100km/hr brings it back around 90 -100km/hr and shifting to 5th doesn't bring it back. It also happens in 3rd and 4th at about 55km/hr to 65 km/hr. Removing the front propshaft doesn't change anything substantially.
Done so far (also in relation to fixing other problems):
- replaced u-joints in both propshafts. Can't feel any play in the sliding joints.
- changed oil in transfer case.
- changed oil in diffs.
- ball joints in drag link/drop arm changed/overhauled (track rod ones seem ok)
- replaced rear wheel bearings and hub seals
- full electrical tune up (new genuine rotor and cap, alternator, coil, ignition module, plugs, leads)
- Head gasket blew 18 months ago and was fixed, but the vibration was there before it went.
- swivel preload checked, is within spec.
- panhard rod bushings replaced.
- rear trailing arms bushings replaced.
- oil level in gearbox is ok, and oil looks ok. (been planning on changing it, but haven't gotten around to it yet).
- overhauled rear brake calipers.
Things to suspect:
- when I changed the u-joints, I found out that the front propshaft was mounted the wrong way around, the manual specifies the sliding joint nearest the transfer case, it was mounted at the diff flange.
- There's noticable play in the bearing of the front output shaft of the BW transfer case.
- I think I can feel some play on the swivel bearings.
- compression imbalance in engine? Injector or two not giving as much fuel as the others, or too much?
- LT77 mainshaft problem, even though the box shifts fine and doesn't jump out of any gear.
Things I think I can rule out:
- front propshaft: even with it removed, the vibration is still there
- wheel balance: same speed, different gear makes it go away.
- alignment: not felt through steering
- front diff
I realize the combination of V8, LT77 and BW is not a very common one
Thank you for any input and ideas,
Ian.