I realize this is a common issue mostly attributed to front driveshaft u-joint failure, but I've just replaced both shafts with parts from lucky 8 (eliminated rear rotoflex).

The vibration begins above 2K RPM and 30MPH under load (accelerating) and continues at all speeds when applying throttle. It's a steady vibration with and audible low humming noise. It is not present when decelerating or under very light throttle.

Full info:

Newly acquired D2, 200K+ mi.
Just installed:
-New balljoints
-New motor and trans mounts
-TF 2" lift
-265/75/16 BFG K02 tires
-Front driveshaft
-Rear shaft w/ conversion kit
-TF steering rods + damper
-TF panhard rod
-Fluid flush in both axles and transfer case
-Ashcroft CDL kit

When I bought the truck <2K miles ago it was not exhibiting this vibration. The balljoints and mounts were shot, and I replaced those and began upgrading the truck.

I installed most these components and had the tires fitted within a couple days and began noticing this noise afterward. The tires seem to be well balanced, and I would expect a balance issue to generate a constant noise not only when accelerating.

I began investigating: pulled off front shaft, drove in CDL, noise still present. I still had the old rear shaft on at this time, so I replaced it and eliminated the slightly worn rotoflex: same noise.

Fluids in both diffs looked good.

Transfer case had been leaking. Drain plug magnet in T-case had more debris than I would like to see (some small silver bits) and low oil volume. I removed inspection cover to examine gears, no evident chipping of teeth. I checked both output flanges for end play, none evident. I checked new shafts for play, none evident. Rotated assemblies with case in neutral, no noise or rough movement.

After re-sealing t-case inspection cover and replacing fluid with 75-140 snyth noise is the same. T-case is still leaking from an area above the cover, presumably input seal area.

I have some front axle seal leaks after replacing the balljoints, not severe and the fluid volume is good in the diff. I ordered new seals and will replace this week.

I've checked hubs for play and bearing feel, no evidence of fault there.

Sorry if longwinded but want to provide all the details. I've been working on European cars for many years, but this is my first Rover and 4x4 so these systems are somewhat new to me.

It seems to me that the noise may be originating in the tcase? Running it low on fluid before I serviced it maybe accelerated some wear? A bearing is beginning to fail? Before I rip it out I wanted to check with you guys here to review and see if I've overlooked something.

I will be putting a lot of miles on this truck and doing some towing, it needs to be fully sorted before the end of this month for it's maiden voyage out of state.

Hope you wise Rover people can point me in the right direction!

 

My opinion is this is a case where buying some lift rack time at a local repair shop might be the only way to pin point the vibration. It could be something simple or it could be the transfer case. Good luck. D*

 

You tried running the truck without the front shaft, but it doesn't look like you tried without the rear shaft. I'd do that to eliminate that as the source of the problem.

 

You are covering a lot of ground under your Rover but you didn't mention the tranny. When was the fluid last changed and does it have enough in there? Often times people don't fill it enough because you have to crank the engine and run through the gears several times to get the last two or three quarts into the tranny.

Might be something to check.

Adding a lift changes the geometry of things under there (obvious I know) but you might also want to eyeball it again from underneath and see if anything looks really out of whack.

Did you have the alignment done after you installed the tires? I did my lift about 6 months after I bought the vehicle, had the tires balanced & installed and then had the same shop do an alignment. It was waaay out of spec. Something else to check.

Good luck with it. I keep on finding out that as I repair or upgrade something the new stuff puts stress on the older parts and sometimes can cause them to fail. One day it will all be new. Or so I keep telling myself!

 

Agreed. I have access to a lift but it's a bit of a drive and I won't be able to get it over there until next week.

 

I have not ran without the rear shaft yet, may do that this afternoon.

I did run with the original rear shaft + rotoflex, then replaced with the new rear shaft and ran again, so I was able to confirm the issue was not in the old shaft/rotoflex assembly.

 

I did check the tranny fluid level and condition. The fluid is clear and box is full. I haven't flushed it yet, waiting on filter and gasket to arrive.

I set the toe with our trackside alignment rig (racing shop). I have not put it on a rack yet, I will do that soon as time allows. I've never seen an alignment issue cause this sort of noise and the truck tracks straight, but I agree it's a variable that should be eliminated.

I've been under it inspecting things quite a bit since this issue emerged, can't ID any obvious visible source of the issue.

My suspicion is internal transfer case issues for that reason, and because of the material on the drain plug when I flushed it. All the other gearboxes showed no debris on the plugs when removed. However I can't find a smoking gun (endplay on the flanges, visible gearset wear, etc) to confirm that, and I know there are many other possible contributing factors. I'm going to recheck all the hubs again this evening among other things.

Thanks for all the input so far guys. I'll keep you posted. It's nice to be able to crowdsource diagnostic opinions, many of you are far more experienced with this platform than I am.

Maybe Disco Mike will chime in with his expert opinion and solve all my problems for me