I was launching at the track in 4wd and had this awful loud groaning sound coming from the drivetain under hard throttle. I couldn't tell where it was coming from. I had to let off and call it quits. I wonder where I should start looking? I remember it doing this once before but with more power now it does it every time.

I'm thinking: Tranfer case clutch or chain, front bearings or CV's, or one of my diffs. Anyone have any insight?

 

my old truck made an awful noise when my T-case chain got slack in it..

 

Have you noticed any drips under where you park the truck? My buddys truck broke the wear clip and very slowly leaked out all the fluid. It made the same noise you are describing.

 

There's a TSB in reference to this, and if you search my "FLT Level7 is finally here!" thread, you'll find pictures that I posted of the new and old clips in question.

The front diffs are prone to breakage of the carrier retainer clips which will cause the carrier to rock around and the bearings to eat themselves. My front diff groans in 4x4 due to this...

Just a couple of common items to inspect...

 

I'd take a look at your modified transmission x-member to see if something back there is touching/rubbing it when the tranny mount compresses under hard launch. I'd also check the engine mounts & tranny mount for wear while you're under there.

 

Thanks for the replies. There are no leaks on this new setup. When I had the transfer case apart, everything looked mint inside. There is plenty of clearance from the crossmember to everything. I remember hearing this with the 5.3/60e on a launch or two. I'll have a look at the tranny mount though. Engine mounts were good. This is a fairly low-mileage truck. It almost sounded like the transfer case chain skipping over some teeth. That would be an easy fix for me but I'm not sure how to troubleshoot that. I'll check the front diff clips as well.

 

If its not one thing its another isnt it bud??? LOL.

Good luck on finding your issue.

So it only does it in 4x4 huh?

I would think its a Tcase issue.

Might help to go in a grass field and put it in 4HI and do some throttle blips, might help ya pin point it.

 

Yes, if it isn't one thing, it's another... or another. You really have to love the pursuit of perfection and have a lot of patience and money. I can see why some guys demod their projects... they've had enough! However, if you're persistent and able to work on your own stuff then it's a hobby that might keep you away from other stupid things. And the successes are rewarding.

Back to the problem. It seems to do it under hard throttle. I'm going to take it out and run some hard 2wd launches tomorrow if it's not raining and verify that this happens only in 4wd.

If it's a chain or front diff it shouldn't make the noise in 2wd, correct?

 

My buddys truck did it in 2wd a couple of times right at the end. It ate the fork that switches from 4wd to 2wd enough for it to let the jump around enough for 4wd to be engaged when it was in 2wd.

 

I looked around underneath again tonight to eliminate some possibilities. I found the front driveshaft to to be rubbing again so I ground some off the u-joint straps and took it for a hard drive. It doesn't seem to be making the noise now but I'll drive it more tomorrow.