Rumbling/Grumbling in Drivetrain

[gavin]

So... I might be jinxing myself, but I think my problem for the last several years has been the tires.
effing tires.

They were getting a bit slim, worse was ~5/32" tread left.

Got some new BFG AT's installed this afternoon.
The short drive home, remarkable difference.
Literally no rumbling or grumbling.

I might be getting my hopes up though, but as it stands, I'm hopeful!

 

[gavin]

Yeah, apparently I just got my hopes up.
Rumbling/grumbling has been back for a while now.
I even replaced the VC in the spare t-case again.

Might the VCs just be prematurely failing?
Thinking I might try one last time, but this time get a VC by Motive Gear, instead of whatever those other ones were.

Only other thing I plan on doing in hopes of resolving this, is replacing the rear leaves and Warrior shackles with a set of the OME 2" lift leaves and putting stock shackles back on.
Local offroad shop here should be able to get the CS042R (replacement for OME-36) at around $180/ea.
Doubtful it's the pinion angle though, as I had (temporarily) ran pinion shims on the rear and it made no noticeable difference.

 

[gavin]

So I'm still curious if these issues could be transmission related.
Surely there's bearings in the transmission, but I'm pretty clueless to the innards.

Issue has persisted through axle swaps, axle re-gears, t-case swaps, and t-case rebuilds.

 

[SWIGIN]

That's a good one and I feel your pain. I just got my Mustang running after 2 years of on and off again trying.

I have real hate in my soul for AWD and VC. I know you don't what to hear this but if taking the front drive shaft off quiets it down then it is the TC. I'd throw that TC as far as you can install a BW4406 and say good bye to those VC problems forever.

That's all I got.

 

[gavin]

I don't see it being the t-case.
It has been swapped and rebuilt more than once.
Issue has persisted through transfer case swaps, t-case rebuilds, axle swaps, axle re-gears.

Currently, NVH is felt in steering wheel, seat, and floor. Issue persists when coasting in neutral.
Removing front shaft removes NVH from steering wheel, and maybe decreases intensity felt in floor and seat; but does not remove it completely.
Been a while since I pulled the the front shaft.

 

[gavin]

I believe the NVH I've been experiencing for the last 10-12 years has been transmission related all along.
Couple weekends ago, on the way home from an early departure of camping, suddenly started experiencing issues with the 1-2 shift; delayed/harsh.
Did filter and fluid, no change. Filter wasn't all that dirty, but there was one (albeit tiny) chunk of shiny metal stuck between the pleats.

Checked everything I could, could not find an issue.

Finally took it to a transmission shop for diagnosis.
They did they routine checks of, fluid level, color, etc.
The shift issue was reproduced.
They also stated that there was an audible noise coming from the transmission, and suspect it's a bearing in the rear of the case. (I have read of the "rear #9 Torrington" being problematic.)
Possibly a piece broke off and got stuck in an accumulator or piston causing the delayed/harsh 1-2 shift.

Being a bearing certainly fits the theory I got a couple months ago.
Harshness persists when vehicle is moving, regardless of gear. Transmission output shaft is always spinning when vehicle is moving.

As every other single part of the driveline has been rebuilt or replaced, sans transmission, it fits.

Will be dropping the rustbucket off on the 24th to get the transmission rebuilt.

 

[gavin]

So going to necro this again.
Transmission was rebuilt and at least shifting issues resolved.
Still this damn NVH.

Starting to think possibly driveline angle related.
Could use input on whether my thought process is correct.

Rear driveshaft angle is about 0.7* out of spec (7.4 spec, actual is 6.7)
Pinion angle pretty close. FSM spec is 5.4, actual is about 5.6

Angle at t-case output flange... FSM doesn't provide that spec, but it does provide "Engine Angle"
Would engine angle be pretty much the same angle as at the t-case output flange?
FSM specs engine angle is 4.75
Actual angle at t-case output flange is about 6.4

Front driveshaft angle is only about 0.4 out of spec. GKN CV joint @ t-case.
Spec is 2.4, actual is 2.8
Unfortunately it doesn't provide spec for front pinion angle or t-case output angle specs.

Measurements and calculations I did.

Rear D/S Angle: 6.7 (spec 7.4)
Rear Pinion Angle: 5.6 (spec 5.4)
Trans Angle: 6.4 (engine angle spec 4.75)
Rear Working Angle: -1.1
Front Working Angle: -0.3
Working Angle Difference: 0.8

Front D/S Angle: 2.4 (spec 2.8)
Front Pinion Angle: 1.7
T-case Angle: -2.6 (most likely inaccurate, nearly impossible to get accurate measurement with shaft installed, and didn't feel like pulling it. This should theoretically be nearly identical to rear output flange angle except angled up, no? It does angle up anyway)
Front (u-joint) Working Angle: 0.7
Rear (GKN cv joint) Working Angle: 4.9 (most likely inaccurate due to probably inaccuracy of t-case angle noted above)
Working Angle Difference: 4.3 (should be irrelevant, due to GKN CV @ t-case)

Specs listed in FSM:
Rear D/S Angle: 7.4
Rear Pinion Angle: 5.4
Front D/S Angle: 2.8

Likelihood of worn motor mounts?
I know I replaced the transmission mount ages ago, after the issue began, and it did not seem to have any impact.
Also looking at specs and my measurements, bringing the transmission up a bit would bring at least the driveshaft angles more in line with spec, and potentially help even out working angle of rear u-joints. Right?