Rear Driveshaft Hitting underbody when accelerating

blakeboys · Post by **blakeboys** » Thu Jul 09, 2009 9:56 pm

I have a 6" Superlift installed on my truck and when I accelerate quickly or slightly peel out of dirt or wet pavement a hear and feel a loud knocking sound like clunk clunk clunk clunk today as i was underneath my truck welding a flowmaster super 40-4 exhaust in I discovered where the noise was coming from. As seen in the pictures the rear driveshaft's u-joint is bouncing up hitting the frame. I pushed up on the rear driveshaft and the transfer case and it lifted up off of a hard rubber piece which it sits on. the u-joint is fine but is this normal for the transfercase, driveshaft, and transmission to move around on this rubber block like this? it kinda bothers me because not only is it embarrassing since everyone outside turns there head but i im sure its eventually gonna cause a whole bunch of problems.

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green02crew · Post by **green02crew** » Thu Jul 09, 2009 10:39 pm

My driveshaft rubbed my gas tank skid plate. Nothing a BFH didn't take care of.

F9K9 · Post by **F9K9** » Fri Jul 10, 2009 3:55 am

First of, welcome to the forum. That rubber mount that you refer to is a transmission mount and it should not separate. It's blown and is allowing much more drive line movement than intended. This was allot more common about 20 yrs ago and it's nothing major. Any parts store will have them in stock. I would be willing to bet that you have a motor mount blown, as, well. Have someone set your parking brake, keep a foot on the brake, and gently rev your engine while you observe with the hood open (standing to the side of your truck). If the driver's side raises up more than an inch, you have a blown engine mount. An engine mount is common to get blown if you are somewhat aggressive with your driving.

blakeboys · Post by **blakeboys** » Fri Jul 10, 2009 9:11 am

ok i checked to see if it was an engine mount and that seems fine. So i priced the transmission mount and it's about $10 at AAP. My question now is how hard is it to replace this?

Post by **HenryJ** » Fri Jul 10, 2009 9:35 am

Four bolts. Jack up the transfercase/transmission and swap. I think there was just enough room without dropping the crossmember.

blakeboys · Post by **blakeboys** » Fri Jul 10, 2009 12:49 pm

ok i think i cant handle that. Thanks for your help. Also when i have time i'll post some picture of my truck .

F9K9 · Post by **F9K9** » Fri Jul 10, 2009 3:53 pm

As for checking the motor mount, I left out the part that it has to be in drive. Did you check it out with it that way?

blakeboys · Post by **blakeboys** » Mon Jul 20, 2009 9:52 pm

I replaced the transmission mount. I did have to remove crossmember

however i did get it on there successfully but afterwards i checked the motor and unfortunately the engine mount is gone too. Question: Is it easy to replace a motor mount or does it require a lift and tools. or do you think i should just have my local mechanic get it over with? thanks

F9K9 · Post by **F9K9** » Tue Jul 21, 2009 9:47 am

From ZR2USA.com