How much transfer case play is acceptable

[i6pwr]

2012 Yukon XL 6.2 AWD. Single speed T-case.

Yukon has 145K, OE T-case, new front and rear driveshafts, I rebuilt the rear a year ago, about .006" backlash, rear is smooth, quiet, no issues, tires are Michelin Defender and are roadforce balanced.

I'm getting a decent vibration throughout the cabin right before 80 MPH, pretty quiet at 70, but as I near 80 it cones on strong and reminds me of a bad driveshaft, but it's smooth up to 60-65, dead silent, but around 70 I can start to barely hear it beginning to vibrate.

Reason I brought up the transfer case is the clunk from D to R after a stop, did this before and after rear was rebuilt. When I let off the gas and coast, then hit the gas, most times I get a clunk so I was thinking the chain. Also, I can move the slip yoke in the tail of the T-case up and down but need to get an accurate measurement of how much. I don't think it's the gap in the splines, but the output shaft itself.

How much moment is normal of the slip yoke? Also, how much rotation is allowed between the front output and rear output? Mainly holding one and turning the other.

Driveshaft RPM at 80 is roughly 2881 RPM.

All input appreciated.

 

[D60]

Fords notoriously had the clunk and allegedly needed special grease in the splines, but that was a slip joint in the d/s itself I believe.

Still, have you tried greasing the splines with a high end grease? May be diagnostic if nothing else.

As for your actual question, I don't know. But I find it unlikely a chain would cause a clunk.

Does this t-case power the front output equally at all times? I doubt it. It likely engages the front more when wheel slip is detected. If so, your front output is more of an idler most of the time and I think that makes a chain clunk even less likely because the chain's not under a lot of tension upon acceleration.

I may not be understanding how this t-case works, however. I'm basing everything off the NP246 with which I am familiar

 

[jetman]

I have a 07 Yukon Denali with 197k miles is awd w/BorgWarner 4485 transfer case that has the infamous "CLUNK".
Recently I researched replacing its chain and bearings. Cost for a DIYer is roughly $250.

 

[D60]

Apparently the 4485 is a 40/60 bias so the front is always powered at 40%.

And chain clunk is not unheard of. I also found a vid where he got a constant noise almost like valvetrain noise. I wonder if this is OP's vibe?


Thank you @jetman !

 

[i6pwr]

Sorry for late reply, I will try to get a video or the actual amount of chain stretch by counter rotating the outputs of the TC.