4WD Clunk from Front

[howeitsdone]

As the title states. When in 4WD (PT & FT) I get a loud clunk and vibration when there is a lot of torque applied. Generally when going up very steep hills or obstacles. 

 

Video below. Doesn't quite do it justice, but hopefully you get the idea. U joints are fine. It feels like it's coming from the front of the transmission almost so I've been thinking something with the front driveline. If I give the same torque in 2WD I don't get the issue.

 

[Pete M]

is your CAD functional?

[howeitsdone]

23 minutes ago, Pete M said:

is your CAD functional?

 

I have a '98 axle

[Pete M]

everything greased?  I've had ujoints go dry and cause noise.  otherwise, I'd look closely at the t-case. 

[cruiser54]

Transfer case fluid level and condition? 

[howeitsdone]

TC fluid was filled in December when installed. Never been rebuilt, but was disassembled for cleaning in October-ish. What in the TC would cause? Chain? And would I hear that from the front of the tranny?

[cruiser54]

Just making sure it's full.

 

Pull the front driveshaft and see if anything is loose in it. 

[howeitsdone]

1 hour ago, cruiser54 said:

Pull the front driveshaft and see if anything is loose in it. 

 

Just had it pulled this week while changing the clutch. No play in any of the u-joints. The front one is new.

[gogmorgo]

Check the double cardan for movement. It should be nice and tight, as in when it’s installed you shouldn’t be able to push it up and down. There’s a spherical and needle bearing between the two joints that can go bad and cause a heck of a vibration in 2wd and in my case also a clunk in 4x4. I’m guessing you didn’t try driving it without the front shaft to see if anything changed?

[Tex06]

On 5/8/2022 at 4:39 PM, gogmorgo said:

Check the double cardan for movement. It should be nice and tight, as in when it’s installed you shouldn’t be able to push it up and down. There’s a spherical and needle bearing between the two joints that can go bad and cause a heck of a vibration in 2wd and in my case also a clunk in 4x4. I’m guessing you didn’t try driving it without the front shaft to see if anything changed?

X2 on pulling the driveshaft and driving. 

[howeitsdone]

Thanks guys, but please read my posts. This has nothing to do with 2wd.

[gogmorgo]

8 hours ago, PocketsEmptied said:

Thanks guys, but please read my posts. This has nothing to do with 2wd.

Yeah we all read the posts. Pull the front shaft, put it in 4x4, drive. If it still makes the noise, now you know that it’s transfer case, and not front axle/driveshaft. But before you pull the shaft, check to see if there’s any wiggle in the double cardon joint. 

[Andy in Pa]

This is something like the torque load is making the exhaust hit the crossmember, or maybe the front driveshaft is hitting the exhaust.  The shifter seems to be moving alot, maybe motor mounts or tranny mount is loose?  Is it factory t-case linkage?  If so, it could be shifting and hitting the trans tunnel slightly.  Can you feel it in the shifter when it does it?  Put a hand on the trans and t-case shifter and see if you feel it as well.  Could simply be the trans shifter hitting on the side of the trans tunnel or metal ring on the internal boot.

[howeitsdone]

I went ahead and took the front DS and TC out to inspect. The bearings seem to be fine, no broken/chipped teeth, and the forks are in good shape in the TC. Seems like the slack is good.

 

The CCV was solid when installed and still felt solid when moving it around. Not sure I'm testing it properly once removed.

 

 

 

[howeitsdone]

5 hours ago, Andy in Pa said:

This is something like the torque load is making the exhaust hit the crossmember, or maybe the front driveshaft is hitting the exhaust.  The shifter seems to be moving alot, maybe motor mounts or tranny mount is loose?  Is it factory t-case linkage?  If so, it could be shifting and hitting the trans tunnel slightly.  Can you feel it in the shifter when it does it?  Put a hand on the trans and t-case shifter and see if you feel it as well.  Could simply be the trans shifter hitting on the side of the trans tunnel or metal ring on the internal boot.

 

It sounds and feels like something getting hung up and then popping free or clunking. The exhaust mount on the crossmember is in good shape and keeping it from moving much. My shifter does move quite a bit. I had just replaced my clutch that same day beforehand so all of that was reinstalled and torqued to spec. The rubber mount looked good, but other than dry rot or cracking I wouldn't know what to look for.

 

I have Azzy's linkage and it's all pretty tight.

[MiNi Beast]

Pinion gears...