Vibration at 40-45 mph, center bearing,'84 300 sd

[can-do]

Greetings,

Just looking for some input about a vibration I feel in the center driveline tunnel area around 40-45mph and subsides around 50 and over. Has anyone had this happen to them, and was it the center support or bearing that was going bad? Any info would greatly be appreciated. If it was your center support or bearing, how'd you get it out? From looking there is a sheet metal plate over the driveline area and no room to work with the car on the ground.

Charles

I had this same vibration at he same speed and then run smooth at a higher speed. Checked everything as well as pull the trani to check the drive plate for cracks. A thousand $ later, guess what, I set the valves as most were very tight and no more vibration. The gasket is about $5bucks and must be replaced.

[kmaysob]

the bearing is easy once you have it up on jackstands. it took me a while because the blots that hold the center support were rusted and broke the heads right off. not fun. once you have it on jacks all you need to do is remove the cover and then undo the driveshaft. make sure you mark the drive shaft so it doesnt get misalined when you put the two halfs back together. then its just like uninstalling it in reverse

[langpfeife]

Replacing all these things will definately help, but oftentimes the u-joint wears and seems to "bind"
under load, and replacing them doesn't appear easy. I'm still trying to find a place locally that will do
mine (and NOT try to sell me a completely rebuilt driveshaft).

There are some factory alignment markings on your driveshaft BTW, two of them (spaced together) on the
larger half, just in front of the u-joint, and a single "nub" on the smaller half, right behind the splines.
(These are not painted, but part of the metal castings.)