Transfer case (?) noise

Maximumwarp

Well-known member
Mar 22, 2015
836
26
Fairburn GA
Last trip I took, I noticed a pretty horrendous noise coming from under the truck. It would happen when I would come off a trail and drive on a paved road after unlocking the CDL. Seemed to coincide with the CDL finally disengaging (it takes it a little while sometimes). By that, I mean that immediately after I switched the CDL off, it wouldn't make the noise, but the more I drove, the louder the noise would get until the CDL released and then it would be fine. I should also note that this noise would only occur under power. Quiet when coasting.

Driveshafts appear to be okay, Tom Woods in the front that gets regular grease. I have a Detroit in the rear, but I'm familiar with its various noises, and this was decidedly different.

Any ideas what this may be? If I have time to get under the truck tonight I'm going to check the fluid level, but I replaced it about 5k miles ago and I haven't seen any leaks.
 

Tugela

Well-known member
May 21, 2007
4,754
562
Seattle
If you think your CDL takes a while to disengage you might try giving it a little help before hitting the pavement. When I shift from low to high range I usually reverse a little ways, then drive forward, repeat as necessary. This seems to do the trick. Not quite to this extreme, but you get the idea:

https://www.youtube.com/watch?v=IGiQOCX9UbM
 

Maximumwarp

Well-known member
Mar 22, 2015
836
26
Fairburn GA
I usually do, but we had a few trucks in line, so I just kept moving forward. We were at Windrock, so lots of "get off this trail, drive a few miles up the road to get to another one". I'm wheeling again Saturday, so I'll try to make sure I try to help it pop out and see if I can duplicate the noise.
 

ezzzzzzz

Well-known member
Apr 22, 2010
604
7
SE Va
The dog clutch (always engaged with the differential housing) engages the front output shaft, via spring pressure on the shift fork shaft, when it rotates in a position allowing the teeth to align. That is why you must engage at slow speed. Pressure is typically on that tooth contact during most operation in diff lock. Backing up allows the teeth to move apart so that pressure is relieved allowing the dog clutch to shift away from the output shaft back fully onto the differential housing when going back to non-diff lock. Continuing to drive forward when disengaging diff lock holds the dog clutch to the output shaft. As it moves backwards, slowly reducing tooth contact, there is distinct possibility of excessive noise.