help, "klunking" noise only in idle while moving

okay, i get this weird klunking noise somewhere under my jeep from the rear.
it only happens when i'm slowing down and downshifting
it is especially noticable when i take it out of gear and come to a stop.
brakes have no effect on the noise. it will increase in noise as i pick up speed in idle downhill
it makes no noise coming up to speed, or once i'm cruising. it's only slowing down in too low of an rpm for the gear i'm in, and really when there is no load on it in nuetral while going around 15-30mph.
i realize coasting is not safe, don't slam me, it's just for trying to find the source.

short of strapping someone under my ride to pinpoint the noise, where should i start?

alittle background on my junk:
2000, nv3550, 231 w/sye installed. 5 inch dpg hybrid kit, 33's, swapped in a dana 44. rear driveshaft is pretty new, built by one of dpg's associates, front shaft was just rebuilt and extended. trutracs front and rear. 4.56's

what i've done: put new brakes on in the rear w/ hardware kit of course.
put it up on jackstands and ran it in gear and can't duplicate the noise.

this only started happening a few weeks after i swapped the 44 in. i took it back to the gear guy and the yoke had play in it. spun the caps on u-joint. i swapped out the yoke and it still does it. gear oil always looks good when i drain it, no metal and i use royal purple.

so what do you all think? last time i posted this and got no response. surely this can't stump the modified tech board. any advice is welcomed and encouraged. thanks-brian

Brian Strickland said:

i realize coasting is not safe, don't slam me, it's just for trying to find the source.

Click to expand...

Huh? Can you get in trouble for that now?

Your noise sounds just like one my xj makes. On mine, the tangs that center the ujoint cups are worn, so the cups move out and the driveshaft clunks at low speeds. I can really hear it below 5 mph. Under torque, this won't happen as it'll stay to one side or the other.

You described virtually the same problem with your yoke, that's my bet. Online diagnosis aside, practically all noises can be found by putting hands on parts.

JJacobs said:

Huh? Can you get in trouble for that now?

Your noise sounds just like one my xj makes. On mine, the tangs that center the ujoint cups are worn, so the cups move out and the driveshaft clunks at low speeds. I can really hear it below 5 mph. Under torque, this won't happen as it'll stay to one side or the other.

You described virtually the same problem with your yoke, that's my bet. Online diagnosis aside, practically all noises can be found by putting hands on parts.

Click to expand...

i meant coasting being unsafe as not being able to respond to sudden need for acceleration to avoid hitting something suddenly. as far as hands on, believe me i've tried everything, short of literally having a friend strap in underneath like Deniro in "cape fear". i replaced the pinion yoke that was loose on the ears. i replaced the drums because i thought they may have a flat spot for sitting for so long. i'm thinking something in my axle housing, i've never had a trutrac make noise before, it's all completely new axle bearings in there along with a complete master install kit when i got my TT and gears. thanks in advance everyone.

Never thought of coasting as unsafe. With gas at 3 bucks a gallon I coast down every hill I find. I must need to check myself.