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Thump when backing up?

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Old Dec 12, 2021 | 11:31 PM
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Default Thump when backing up?
I’m getting a mild thumping sound from the back after backing up a couple yards. I have a manual 4 speed. I only notice it once as I back out of the garage and nothing after that. Seems it may be a u-joint?
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Old Dec 12, 2021 | 11:42 PM
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I have a 72, modded quite a bit, and I have been chasing the same thing, unsuccessfully. Thumps once when backing out of garage if not used recently, then it goes away. Could it be something with the e-brake?
Last edited by Flivver61; Dec 12, 2021 at 11:43 PM. Reason: Spelling
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Old Dec 13, 2021 | 02:58 AM
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Check the nose mount for the diff. The rubber cushions might be deteriorated and reversing it's pulling down and thumping
m
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Old Dec 13, 2021 | 08:25 AM
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mine does as well 79 4m.. still not figured it out..
new joints all around, new snubber (still snug).. rebuilt tranny. doesn't do it all the time.. and only one thump when in reverse and loading a little harder..
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Old Dec 13, 2021 | 08:45 AM
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Went thru this several years ago and it turned out to be worn u-joints.
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Old Dec 13, 2021 | 09:43 AM
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U-joints including the four on the half shafts are probable culprits.
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Old Dec 16, 2021 | 11:24 AM
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Originally Posted by CiCiC3
I’m getting a mild thumping sound from the back after backing up a couple yards. I have a manual 4 speed. I only notice it once as I back out of the garage and nothing after that. Seems it may be a u-joint?
well.... i figured mine out..
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Old Dec 16, 2021 | 11:50 AM
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Originally Posted by interpon
well.... i figured mine out..
https://youtu.be/sdP-cBVfGlY
Nice detective work, interpon! Thank you for sharing.
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Old Dec 16, 2021 | 05:41 PM
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Differential snubber bushing would be my first guess.
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