Knock!!

[Nate4d]

evrytime i take off from a stop i hear a loud clunk from what sounds like the rear end. i wish i could tell ya more but thats all i got. very weird. doesnt affect driving just annoying. anybody?

[Rover]

in your f-150 or jeep? also is the f150 2wd?

[Nate4d]

its the jeep im an idiot. no the 150 is 4x4

[MuddyPaws 3.0]

Something rolling around behind the back seat?

[Rover]

id get under there and make sure everythings tight first. just for kicks check your rear drive shaft for play, ive also seen some cars with rear drum breaks get filled up with dust and make a knock noise durring take off. (im guessing you got drums on the back)

[Nate4d]

yea i have drums. hate em but i got em. im gonna check under to check for tightness. an all. what is pinion slap? ive heard of it just never experienced it.

[BIGBEN]

whenever my jeep makes the same type of noise it is because the u-joint at the rear axle is failing again.

[Rover]

Something rolling around behind the back seat?

dident even think of that :banghead:

[Nate4d]

i dont have a back seat. just a bunch of shit and i drove it without any of it in to see if thats what it was. not it.

[MuddyPaws 3.0]

Loose screw behind the wheel?

[ladiekilla04]

i'd check the drums, they made a similer noise for me, went to check them out, and everything just fell out

[Grandman]

put it in neutral and see how much you can turn the rear shaft back and forth . Rear u joint or pinion bearing . The D shaft should turn a little but not much . Try lifting up and down to make sure the pinion is not flopping all over .

[sglide]

put it in neutral and see how much you can turn the rear shaft back and forth . Rear u joint or pinion bearing . The D shaft should turn a little but not much . Try lifting up and down to make sure the pinion is not flopping all over .X2, also, is your rear squating on take off?
jump up and down on the rear bumper to see it the noise happens, if it does look closely at your bushings in your shocks, control arms, and panhard

[Tonka]

tj's can also make this noise when the control arm bushings wear in the rear, or if the bolts were a little bit loose and the holes slightly enlongated.

On taller short arm lifts, shock contact with the lower rear coil buckets will do this.

I would also check the shock bushings and sleeves, as sglide mentioned.

I had a lower rear shock bushing sleve rot out, and the bar pins/ lack of bushing preload lead to clunks

[Blackjackbender]

i was going to mention UCA bushings also. check them out.