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Old 10-01-2019, 09:52 AM
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Single knock when taking off?

I've recently noticed a knock from what sounds like the rear axle when I accelerate from a stop. I'm wondering how I can troubleshoot this w/o paying a shop $75 to diagnose it. Anyone have an idea what this could be?

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Old 10-01-2019, 09:59 AM   #2
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torque your control arms, your shock bolts, your track bar bolts and every other bolt. Usually the cause is something loose. I had a very pesky clunk and found a buddy had placed a nice round rock in the back bumper (Shrockworks bumper had a cavity just big enough for a golf ball size rock) We all had a good laugh. it was pay back for putting the "sorry girls I am gay" bumper sticker on his that took him a month to notice.
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Old 10-01-2019, 11:29 AM   #3
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I've recently noticed a knock from what sounds like the rear axle when I accelerate from a stop. I'm wondering how I can troubleshoot this w/o paying a shop $75 to diagnose it. Anyone have an idea what this could be?
I have the same issue as you but I haven't looked at it yet. If I remember correctly, there was a thread from a guy that found the inner fender liner was rubbing on something. Like I said, if I remember right.
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Old 10-01-2019, 11:36 AM   #4
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Rear Lower Control Arms did it for me. Tightened them up and it went away for a while.
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Old 10-23-2019, 09:57 AM   #5
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Rear Lower Control Arms did it for me. Tightened them up and it went away for a while.
Tried that the day you wrote this. No luck, so I tightened all of the control arms, upper and lower. Well, attempted to anyway. Everything is the definition of tight and nothing will go any further. Thought maybe a driveshaft u-joint was popping but that's not it either. Does anyone have any direction that I and others can go towards to find and eliminate this issue?
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Old 10-23-2019, 10:09 AM   #6
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Ended up being the rear end for me. Thank goodness they covered it under warranty. I went through the tighten every bolt thing also.
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Old 10-23-2019, 03:19 PM   #7
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If it's none of the above, and if you have the factory TracLok LSD, that could be the culprit. Tons of threads on here about chipped spider gears, etc and resulting "acceleration clunking" noises.
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Old 10-23-2019, 09:38 PM   #8
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My JK was just in the shop for a very similar sound - clunk, pop, knock sound from the rear when starting from a stop.

One thing you might want to do is replace the oil if the diff only to see if you have metal pieces on the magnetic drain plug. If so, I would bet a pay check your spider gears are chipped.

My shop replaced the rear drive shaft, carrier, ring and pinion gears - under warranty. I would have certainly gone to the after market if it was out of warranty.
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Old 10-24-2019, 02:23 AM   #9
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My JK was just in the shop for a very similar sound - clunk, pop, knock sound from the rear when starting from a stop.
One thing you might want to do is replace the oil if the diff only to see if you have metal pieces on the magnetic drain plug. If so, I would bet a pay check your spider gears are chipped.
My shop replaced the rear drive shaft, carrier, ring and pinion gears - under warranty. I would have certainly gone to the after market if it was out of warranty.
They recommend to change the gear oil at 10 to 15k. The tech said for some reason the jku is harder on the rear than the jk is. The carrier was bad and the spider gears were coming apart. They said the oil was nasty and it had 12k on it. I figured it was going to be a battle because I do all my own service and I'm on 35's. All they wanted was a copy of my records. They covered that the rocker rollers and did the airbag recall in one shot. The only strange thing is my uconnect doesn't do text anymore after the visit.

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