Bad vibrations after accidentally allowing transmission to sag without support. HELP! -
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post #1 of 5 Old 08-03-2017, 02:33 PM Thread Starter
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Bad vibrations after accidentally allowing transmission to sag without support. HELP!

Hey everyone,

I was changing my muffler today, so I dropped my transmission/T-case skid plate and cut out my muffler. Once I did that the tranny and t-case dropped a good 8-10 inches and hung unsupported for about 30 seconds while I ran a floor jack over to it (once I removed the skid plate all of the weight went to the muffler, once I cut that out, everything dropped until the u-joints stopped it. I changed out the muffler and the transmission mount to an OEM rubber one. I put the skid plate back up and aligned everything, put all of the bolts back in tightly and fired the jeep up. I noticed right away that the truck is running rough and shaking a good amount at idle whether or not I am in gear or not (manual transmission), however, once I the vehicle starts moving, no vibrations at all. I got the truck up to 45 and everything sounded and felt fine. I am not sure what is going on or what type of damage I may have done. Yes, it was stupid and I should not have happened, I know I also installed a 2" BB, but that was over a week ago and it has not given me any problems since installing it.

2006 Jeep TJ 4.0 6 speed manual

Thank you to those who help,



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post #2 of 5 Old 08-03-2017, 02:44 PM
Jerry Bransford
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The front motor mounts are what take the strain when the rear of the engine/transmission/transfer case assembly is unsupported. It's possible one of the motor mounts was damaged.

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post #3 of 5 Old 08-04-2017, 08:09 AM
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Originally Posted by MCherkerzian View Post
...I changed out the muffler and the transmission mount to an OEM rubber one...
What was it before? What engine mounts are you running? If the engine and transmission mounts aren't made of the same material, it can cause some extra low-RPM vibes. Also, in my experience, new mounts tend to transmit more vibes when first installed, until they break-in/settle/whatever.
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post #4 of 5 Old 08-04-2017, 12:08 PM
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Fan shroud/ blade damage?

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post #5 of 5 Old 08-04-2017, 02:16 PM
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Had you disconnected the transmission mount from the skid plate before removing it? Or from the transmission? If not, and if you broke the mount when dropping the skid plate, that might've caused it. Good news is that it's cheap, easy to replace, and the bushings are usually wore out anyway.

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drive , line , mount , transmission , vibration

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