Transfer case adapter keeps cracking

[CTUBS8732]

My transfer case adapter keeps cracking on me. I've already replaced it twice. This is my 3rd time having to replace it.

I've replaced all 3 seals on the transfer case. Trans fluid is still making its way in the transfer case. I don't know if that's what's causing the adapter to crack. high pressure build up? I heard a loud pop when taking off quick from a stop and sure enough 2 days later I notice spots in my driveway. Truck also made a loud pop noise and some metallic tapping when leaving my driveway. It sounding like bad ujoint noise but only does it intermittently. I checked the drive shaft and it is snug.

I'm kinda left clueless as to what it could be. Any help would be greatly appreciated. I've been having to take my wife's car to work. It's all bedazzled lol.

 

[Mudsport96]

I don't know if you have any mods or not so I will just put out general ideas.
1. Rear suspension geometry is out of whack and hard acceleration tries to straighten everything out and side loads the tailshaft. Thus cracking the case adapter.
2. Bad engine mounts allow the engine and trans to rock. And the case adapter is taking the brunt of the load and breaking. I would lean more towards this one.
3. Too much hp and tq. But unless you have SERIOUS mods I don't think this is it.

 

[strutaeng]

I can't remember, but don't worn u joints also cause these issues?

Any lift? That definitely changes the angle of the driveshaft. Sometimes it's a little bit, sometimes it's a lot (depending if it's a single piece vs 2 piece, but I think all SUVs are single piece?)

 

[Fless]

If trans fluid is migrating to the transfer case, it's time for some work on the tranny.

 

[CTUBS8732]

@Fless What in the tranny could be causing this?
@Mudsport96 engine mounts and tranny mount is my first step.
Literally the only thing I can think of.
But as for the atf getting in the tcase I don't get it? I changed the seals. Maybe if it is the mounts the shaft is moving and wearing out the seal?

@strutai Checked the drive shaft by hand and its snug. I have no lift or level kit. I do have a intermittent clunk that sounds like the ujoints. Taking off the other day it made a pop noise, then a clack clack clack. Hasnt done the clacking again but the pop yeah.

I'm just plain confused.
I thought atf goes in the adapter to keep the shaft lubed. There's a spout looking thing on the back end of the tranny on the bottom. Looks like it's kinda aimed to shoot fluid at the shaft.

 

[strutaeng]

@strutai Checked the drive shaft by hand and its snug. I have no lift or level kit. I do have a intermittent clunk that sounds like the ujoints. Taking off the other day it made a pop noise, then a clack clack clack. Hasnt done the clacking again but the pop yeah.

I'm just plain confused.
I thought atf goes in the adapter to keep the shaft lubed. There's a spout looking thing on the back end of the tranny on the bottom. Looks like it's kinda aimed to shoot fluid at the shaft.

Umm...I think you need to look into that popping sound for sure.

I'm not familiar with the 4L60e-family, but I don't believe the tailshaft is lubricated internally (but there is a seal in there that separates the ATF and TC fluid.

The spout looking thing is just a breather. The transmission and transfer case each have one of those.

 

[Mudsport96]

Umm...I think you need to look into that popping sound for sure.

I'm not familiar with the 4L60e-family, but I don't believe the tailshaft is lubricated internally (but there is a seal in there that separates the ATF and TC fluid.

The spout looking thing is just a breather. The transmission and transfer case each have one of those.

The popping is most likely the crack in the adapter working back and forth on itself and making the noise. I've had cracked flex plates sound like rod knock because the crack flexing on itself.

 

[Mudsport96]

Is the adapter cracking in the same area or close to it?

 

[CTUBS8732]

The adapter just cracks. I'm leaning more towards bad mounts. I got under there and checked the drain plug just to see if it was snug and the tcase moves when putting a little torque on the ratchet..

 

[ivin74]

Bad mounts for sure.