Horrible Drivetrain Grinding Noise

[AZPiNsTrIpEd]

Ok this noise is gonna make me go nucking futs Its a loud grinding noise and it sounds like it's coming from the T-case but i'm not sure. It only happens when I let off the gas in OD not in D. I've replaced all my U-joints front and rear, and still no luck. I even put in zero rates thinkin the extra driveshaft length would help, with no luck. I've read that it could be a loose chain in the T-case or slop in the gears, but I dont think its the rear end. Any one have any other ideas??????

Oh yeah the truck is:
350/700/208/10b/14ff w/detroit

 

[MTMike]

How much lift are you running? I had this in my truck when it had 12" of lift and every time I let off the gas it would do that. Turns out it was a driveline vib even though it sounded like gears grinding when I let off the gas. When I lowered it to ~4.5" it went away.

Hope this helps.

 

[hunterguy86]

I had the same issue with my 86 k5 when I put on my 4 inch lift.

I lowered the t-case 1 inch and it solved the issue.

the tcase drop is a free mod. If you look at the bolts that hold the crossmember to the frame there are 1 inch spacers above the frame rail. Take out the bolts and put the spacers between the frame and crossmember. Here is a picture of the spacers before I moved them. These 2 were below the crossmember, the 2 on the otherside were above the frame.

Hope this helps

 

[AZPiNsTrIpEd]

I have 4" suspension and 2" body. I already lowered my t-case about a 1/2 inch but maybe I should lower it some more. Anyone else have this problem?

 

[sarasotausmc]

I have the exact same problem, changed the ujoints, no help. When I get home, guess I'm lowering the T-case to see if it helps. I've learned to feather the gas just right to lessen the noise on deceleration.

 

[3 on the tree]

I don't know much about lifts. Why would the noise only occur in OD, but not D, if the noise was the T case.? Isn't there some type of one way clutch set up in the OD gearset? I would bet on that going south.

 

[obijuan]

i have that exact same problem, i have the 700r with a 6 inch susp lift and 35's and just had 3000 dollars worth of tranny reconditioning and the tranny guys didnt worry about it too much. i asked him and he said it was nothing of concern. that could be just to get my money again later or it could be the truth. its been a few months since and ive just learned to ease the gas to get it to quit.

 

[81jimmyslt]

I had the same symptoms with my 208, I posted a few questions but not much help. I also messed around with the crossmember and joints with no luck. The problem persisted........and eventually my T-case cracked completely in half while I was on the freeway going over a bridge, spit my driveshaft in middle of the road.